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Publikacje

2017

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2016

  1. M. Bazarnik, B. Bugenhagen, M. Elsebach, E. Sierda, A. Frank, M.H. Prosenc, R. Wiesendanger
    "Toward Tailored All-Spin Molecular Devices"
    Nano Letters 16(1) (2016) 577-582

    Abstract

     Molecular based spintronic devices offer great potential for future energy-efficient information technology as they combine ultimately small size, high-speed operation, and low-power consumption. Recent developments in combining atom-by-atom assembly with spin-sensitive imaging and characterization at the atomic level have led to a first prototype of an all-spin atomic-scale logic device, but the very low working temperature limits its application. Here, we show that a more stable spintronic device could be achieved using tailored Co-Salophene based molecular building blocks, combined with in situ electrospray deposition under ultrahigh vacuum conditions as well as control of the surface-confined molecular assembly at the nanometer scale. In particular, we describe the tools to build a molecular, strongly bonded device structure from paramagnetic molecular building blocks including spin-wires, gates, and tails. Such molecular device concepts offer the advantage of inherent parallel fabrication based on molecular self-assembly as well as an order of magnitude higher operation temperatures due to enhanced energy scales of covalent through-bond linkage of basic molecular units compared to substrate-mediated coupling schemes employing indirect exchange coupling between individual adsorbed magnetic atoms on surfaces.

2015

  1. A. Racis, L. Jurczyszyn, M. Bazarnik, W. Koczorowski, A. Wykrota, R. Czajka, M.W. Radny
    "Self-organisation of inorganic elements on Si(001) mediated by pre-adsorbed organic molecules"
    Physical Chemistry Chemical Physics, 17 (2015) 23783-23794

    Abstract

     A combined theoretical and experimental study on the adsorption of an isolated benzonitrile molecule on the Si(001) surface, followed by the adsorption of Al (group III), Pb (carbon group) and Ag (transition metal) is presented. It is shown that two new adsorption sites with enhanced reactivity are formed on the surface in the vicinity of the pre-adsorbed molecule. This is evidenced by the increase of the calculated binding energy of the metallic ad-atoms adsorbed at these sites. Experimentally, this enhanced local reactivity of the modified surface is only partially retained when more metallic atoms are adsorbed on the modified surface at room temperature. This is evidenced by the formation of 1-dimensional atomic chains (Pb, Al) attached to one side of the pre-adsorbed molecule.
  2. M. Bazarnik, L. Jurczyszyn, R. Czajka, K. Morgenstern
    "Mechanism of a molecular photo-switch adsorbed on Si(100)"
    Physical Chemistry Chemical Physics, 17 (2015) 5366-5371

    Abstract

     We present a very compact molecular photoswitch on the technologically important Si(100) surface. Its adsorption configuration is determined by a combined scanning tunneling microscopy (STM) and density functional theory (DFT) study. The mechanisms of the isomerization reactions are discussed in view of DFT calculations and proven by in situ light irradiation.
  3. M. Bazarnik, R. Decker, J. Brede, R. Wiesendanger
    "Multi-layer and multi-component intercalation at the graphene/Ir(111) interface"
    Surface Science, 639 (2015) 70-74

    Abstract

     We present a scanning tunneling microscopy study of Fe and Co intercalated at the graphene–Ir(111) interface. In the case of Fe, we investigate the morphology of the surface with respect to the annealing temperature, which activates the intercalation, and as a function of coverage. By increasing the coverage we show that it is possible to intercalate multilayers at the interface. Finally, we demonstrate that the successive intercalation of Co and Fe for the same sample leads to distinct adjacent intercalation areas.
  4. S. El-Ahmar, A. A. Poźniak
    "Modeling the planar configuration of extraordinary magnetoresistance"
    Journal of Physics D: Applied Physics, 48 (2015) 205101

    Abstract

     Recently the planar version of the extraordinary magnetoresistance (EMR) magnetic field sensor has been constructed and verified in practice. Planar configuration of the EMR device gives many technological advantages, it is simpler than the classic and allows one to build the sensor using electric materials of the new type (such as graphene or topological insulators) much easier. In this work the planar configuration of the EMR sensor is investigated by performing computational simulations using the finite element method (FEM). The computational comparison of the planar and classic configurations of EMR is presented using three-dimensional models. Various variants of the geometry of EMR sensor components are pondered and compared in the planar and classic version. Size of the metal overlap is considered for sensor optimization as well as various semiconductor-metal contact resistance dependences of the EMR signal. Based on computational simulations, a method for optimal placement of electric terminals in a planar EMR device is proposed.
  5. Z. Pietralik, Ż. Kołodziejska, M. Weiss, M. Kozak
    "Gemini Surfactants Based on Bis-Imidazolium Alkoxy Derivatives as Effective Agents for Delivery of Nucleic Acids: A Structural and Spectroscopic Study"
    PLoS ONE, 10(12) (2015) e0144373

    Abstract

     The success rate of gene therapy depends on the efficient transfection of genetic material into cells. The golden mean between harmlessness and high effectiveness can be provided by synthetic lipid-like molecules that are similar to the components of biological membranes. Cationic gemini surfactants are one such moiety and because of their favourable physicochemical properties (double positive electric charge, reduced toxicity, low values of critical micelle concentration), they show great potential as delivery system components for genetic material in gene therapy. The aim of this study was to investigate the process of the complexation of cationic gemini surfactants with nucleic acids: double-stranded DNA of different sizes (21 bp, ~185 bp, ~20 kbp) and siRNA (21 bp). The tested series of dicationic surfactants consists of bis-imidazolium quaternary salts with varying lengths of hydrophobic side chains (m = 5, 6, 7, 8, 9, 11, 12, 14, 16). On the basis of the data obtained by circular dichroism spectroscopy and electrophoresis, we concluded that the studied gemini surfactants with long side chains effectively bind nucleic acids at low concentrations, which leads to the formation of stable lipoplexes. Images obtained by atomic force microscopy also confirmed the formation of vesicular structures, i.e., complexes between DNA and surfactants. The cytotoxicity of selected surfactants was also tested on HeLa cells. The surfactant toxicity significantly depends on surfactant geometry (the length of hydrophobic chain).
  6. A. Wykrota, M. Bazarnik, R. Czajka, K. Morgenstern
    "A molecular switch based on the manipulation of 1,3-dichlorobenzene on Ge(001) between two adsorption sites by inelastic tunneling electrons"
    Phys. Chem. Chem. Phys. 17 (2015) 28830-28836

     Abstract

     Meta-dichlorobenzene is adsorbed on Ge(001) and investigated by low temperature scanning tunneling microscopy. The molecule is altered between two adsorption sites by inelastic electron tunneling manipulation. These adsorption sites differ largely in conductivity. The necessary energy for switching the molecule between the sites and its polarity dependence indicate that the manipulation is initiated by the electronic excitation of the molecule.
  7. M. Baczyńska, M. Regel-Rosocka, M. Nowicki, M. Wiśniewski
    "Effect of the structure of polymer inclusion membranes on Zn(II) transport from chloride aqueous solutions"
    Journal of Applied Polymer Science, 132(30) (2015) 42319

    Abstract

    This article presents application of polymer inclusion membranes (PIM) containing polymer matrices: cellulose triacetate (CTA) or poly(vinyl) chloride (PVC), o-nitrophenyloctyl ether (NPOE) as a plasticizer and phosphonium ionic liquids, i.e., trihexyltetradecylphosphonium chloride (Cyphos IL 101), bis(2,4,4-trimethylpentyl)phosphinate (Cyphos IL 104) and tributyltetradecylphosphonium chloride (Cyphos IL 167), as carriers for Zn(II) transport from chloride medium. Cyphos IL167 application as an ion carrier in PIMs is reported for the first time. The membrane composition is found to affect Zn(II) transport significantly. SEM and AFM images show the differences in the surface morphology of PVC and CTA based membranes. Better transport abilities of CTA membranes (Zn(II) recovery factors exceed 80%) compared with those of PVC, indicate that the structural differences between the two polymers play a crucial role for the membrane permeability. The best initial flux and permeability coefficient are obtained for the membranes with Cyphos IL 101 and Cyphos IL 104 as carriers.
  8. P. Jezowski, M. Nowicki, M. Grzeszkowiak, R. Czajka, F. Béguin
    "Chemical etching of stainless steel 301 for improving performance of electrochemical capacitors in aqueous electrolyte"
    Journal of Power Sources, 279 (2015) 555-562

    Abstract

    The main purpose of the study was to increase the surface roughness of stainless steel 301 current collectors by etching, in order to improve the electrochemical performance of electrical double-layer capacitors (EDLC) in 1 mol L-1 lithium sulphate electrolyte. Etching was realized in 1:3:30 (HNO3:HCl:H2O) solution with times varying up to 10 min. For the considered 15 mu m thick foil and a mass loss around 0.4 wt.%, pitting was uniform, with diameter of pits ranging from 100 to 300 nm. Atomic force microscopy (AFM) showed an increase of average surface roughness (Ra) from 5 nm for the as-received stainless steel foil to 24 nm for the pitted material. Electrochemical impedance spectroscopy realized on EDLCs with coated electrodes either on as-received or pitted foil in 1 mol L-1 Li2SO4 gave equivalent distributed resistance (EDR) of 8 Omega and 2 Omega, respectively, demonstrating a substantial improvement of collector/electrode interface after pitting. Correlatively, the EDLCs with pitted collector displayed a better charge propagation and low ohmic losses even at relatively high current of 20 A g(-1). Hence, chemical pitting of stainless steel current collectors is an appropriate method for optimising the performance of EDLCs in neutral aqueous electrolyte.
  9. M. Wladyka-Przybylak, D. Wesołek, S. Rojewski, R. Gąsiorowski, W. Gieparda, K. Bujnowicz, H. Maciejewski, R. Wójcik, M. Nowicki
    "Synergistic Effect of Modified Natural Fibres with Halogen-Free Fire Retardants in Reducing Flammability of Composites"
    J. Biobased Mater. Bioenergy, 9 (2015) 115-127

    Abstract

    Silanization process was used to improve adhesion of hydrophilic hemp fibers with a hydrophobic polypropylene matrix. The modification of fibers was carried out using 3-(diethylenetriamine)propyltrimetoxysilane. Natural fibres reinforced composites (NFRC) were obtained by mixing the polypropylene (PP) with untreated and silane modified hemp fibres using co-rotating twin screw Leistritz extruder. The flame retardants such as multiwalled carbon nanotubes (CNT), ammonium polyphosphate (APP), guanidinium carbonate (GC), pentaerythritol (PEr) and melamine polyphosphate (MPP) were introduced into the NFRC by a Dynisco laboratory extruder. The influence of silanization process on the chemical structure of fibers was studied by Fourier transform infrared spectroscopy (FTIR). The surface morphology of the untreated and silane treated fibres and their impact on the polymer matrix were characterized by scanning electron microscopy (SEM). Interactions between the additives and their impact on the thermal stability of the fibres, polymers and composites was investigated using thermogravimetric analysis (TGA). Combustibility measurements were carried out by pyrolysis combustion flow calorimeter (PCFC). The improvement in the thermal stability of hemp fibres as a result of silanization process and higher efficiency of modified fibers in reducing the flammability of polypropylene were found as compared with the unmodified fibers. The results showed synergistic effect between silanized hemp fibres and carbon nanotubes in reducing flammability and increasing thermal stability of the composites. All of the used compounds in combination with silanized natural fibres decrease flammability of polypropylene with the best results observed for ammonium polyphosphate and melamine polyphosphate.
  10. L. Słomińska, R. Zielonka, L. Jarosławski, A. Krupska, A. Szlaferek, W. Kowalski, J. Tomaszewska-Gras, M. Nowicki
    "High pressure impact on changes in potato starch granules"
    Polish Journal of Chemical Technology, 17(4) (2015) 65-73

    Abstract

    Air dry potato starch (84.9% d.s.) was subjected to pressurizing under the pressure of 50, 100, 250, 500, 750, 1000 and 2000 MPa for 1 h. The physical properties of pressurized starch, such as morphology, surface and crystalline structure, gelatinization parameters, were studied by means of scanning and atomic force microscopy (SEM/AFM), X-ray diffraction (X-ray), differential scanning calorimetry (DSC). The susceptibility to the amylolytic enzyme (α-amylase) was also measured. Application of pressure in the range of 50–2000 MPa results in an increase in the compressed potato starch bulk density, change in the contours of the granules from oval to polyhedral, increase in the roughness of the granule surface, vanishing of the X-ray reflexes generated by the orthogonal structure and weakening of the reflexes generated by the hexagonal structure, lowering of the enthalpy of starch gelatinization, and the enhancement of hydrolytic susceptibility of starch granules to the amylolytic enzyme.
  11. P. Żak, B. Dudziec, M. Dutkiewicz, M. Ludwiczak, B. Marciniec, M. Nowicki
    "A new class of stereoregular vinylene-arylene copolymers with double-decker silsesquioxane in the main chain."
    J. Polym. Sci. Part A: Polym. Chem., 54(8) (2015) 1044-1055

    Abstract

    A synthesis of a new macromolecular class of vinylene-arylene copolymers with double-decker silsesquioxane in the main chain is presented. Two transition-metal-catalyzed processes, which is silylative-coupling copolycondensation (SCC) and ADMET copolymerization of divinyl-substituted double-decker silsesquioxanes (DDSQ-2SiVi) with selected diolefins, are reported to be highly efficient tools for the formation of stereoregular copolymers containing DDSQ-silylene-vinylene-arylene units. The copolymeric products are studied in terms of their structural, thermal, and mechanical properties.

2014

  1. R. Decker, M. Bazarnik, N. Atodiresei, V. Caciuc, S. Blügel, R. Wiesendanger
    "Local tunnel magnetoresistance of an iron intercalated graphene-based heterostructure"
    Journal of Physics Condensed Matter, 26 (2014) 394004

    Abstract

     The lateral variation of the tunnel magnetoresistance (TMR) of a graphene-based vertical heterostructure is studied by spin-polarized scanning tunneling microscopy (SP–STM) using an Fe-coated probe tip. The well-defined heterostructure is obtained by the intercalation of a magnetic Fe monolayer at the graphene/Ir(111) interface. Its structure is characterized by a moiré pattern with a high corrugation. In contrast to the Fe/Ir(111) surface, graphene/Fe/Ir(111) exhibits ferromagnetic order with an out-of-plane easy magnetization axis. At the nanometer scale, our experiments reveal that the moiré pattern induces a lateral variation of the TMR, which reaches 80%. The measured TMR at valleys of the moiré pattern is higher than at hills. We interpret this modulation in terms of a different hybridization between graphene and Fe at valleys and hills due to a different graphene–Fe distance at these sites, which leads to a different transmission of spin-polarized states.
  2. J. Brede, N. Atodiresei, V. Caciuc, M. Bazarnik, A. Al-Zubi, S. Blügel, R. Wiesendanger
    "Long-range magnetic coupling between nanoscale organic–metal hybrids mediated by a nanoskyrmion lattice"
    Nature Nanotechnology, 9 (2014) 1018-1023

    Abstract

    The design of nanoscale organic–metal hybrids with tunable magnetic properties as well as the realization of controlled magnetic coupling between them open gateways for novel molecular spintronic devices. Progress in this direction requires a combination of a clever choice of organic and thin-film materials, advanced magnetic characterization techniques with a spatial resolution down to the atomic length scale, and a thorough understanding of magnetic properties based on firstprinciples calculations. Here, we make use of carbon-based systems of various nanoscale size, such as single coronene molecules and islands of graphene, deposited on a skyrmion lattice of a single atomic layer of iron on an iridium substrate, in order to tune the magnetic characteristics (for example, magnetic moments, magnetic anisotropies and coercive field strengths) of the organic–metal hybrids. Moreover, we demonstrate long-range magnetic coupling between individual organic–metal hybrids via the chiral magnetic skyrmion lattice, thereby offering viable routes towards spin information transmission between magnetically stable states in nanoscale dimensions.
  3. T. Grzela, W. Koczorowski, G. Capellini, R. Czajka, M. W. Radny, N. Curson, S. R. Schofield, M. A. Schubert, T. Schroeder
    "Interface and nanostructure evolution of cobalt germanides on Ge(001)"
    Journal of Applied Physics, 115 (2014) 074307

    Abstract

    Cobalt germanide (CoxGey) is a candidate system for low resistance contact modules in future Ge devices in Si-based micro and nanoelectronics. In this paper, we present a detailed structural, morphological, and compositional study on CoxGey formation on Ge(001) at room temperature metal deposition and subsequent annealing. Scanning tunneling microscopy and low energy electron diffraction clearly demonstrate that room temperature deposition of approximately four monolayers of Co on Ge(001) results in the Volmer Weber growth mode, while subsequent thermal annealing leads to the formation of a Co-germanide continuous wetting layer which evolves gradually towards the growth of elongated CoxGey nanostructures. Two types of CoxGey nanostructures, namely, flattop- and ridge-type, were observed and a systematic study on their evolution as a function of temperature is presented. Additional transmission electron microscopy and x-ray photoemission spectroscopy measurements allowed us to monitor the reaction between Co and Ge in the formation process of the CoxGey continuous wetting layer as well as the CoxGey nanostructures.
  4. A. Wykrota,  W. Koczorowski,  R.Czajka
    "Functionalization of Si (100) surface with benzonitrile molecules in an ultra-high-vacuum molecular evaporator"
    Materials Science in Semiconductor Processing, 17 (2014) 168-172

    Abstract

     We investigated benzonitrile adsorption on Si(1 0 0) deposited in a home-made molecular source using scanning tunneling microscopy (STM). A high-purity molecular source was constructed for evaporation of organic molecules in the liquid phase. The molecular flux and deposition rate are stable over time and yield good control of the coverage level to less than one monolayer. The method described for creation of a molecular beam can be extended to various molecules in the liquid phase under ambient conditions and substrates. To confirm the reliability of our results, we used benzonitrile molecules on Si(1 0 0) as a substrate that is highly demanding in terms of the vacuum quality (residual gases and impurities) and level. The results were compared with previously obtained results using STM and theoretical methods. This simple molecular source yields enhanced measurement possibilities for different experimental systems without the need for significant investment or system modifications. A simple model is presented to predict the expected coverage and to evaluate device parameters appropriate for the evaporated material.
  5. M. Sadej, E. Andrzejewska, B. Kurc, H. Gojzewski, T. Jesionowski
    "Surface-Dependent Effect of Functional Silica Fillers on Photocuring Kinetics of Hydrogel Materials"
    Journal of Polymer Science, Part A: Polymer Chemistry, 52 (2014) 3472-3487

    Abstract

     Two types of silica: precipitated (P, prepared in non-polar media, a new type, submicrometer sized) and fumed (F, nanosized), both unmodified and surface modified are investigated as functional fillers for potential applications in nanocomposites with poly(2-hydroxyethyl methacrylate) matrix. Special attention is paid to the kinetics of composite formation in an in situ photopolymerization process. Silica-containing formulations polymerize faster; this effect is much stronger for silica P having much larger particle size than silica F. Surface treatment leads to further acceleration of the polymerization in case of silica P but to retardation in case of silica F; the effect of modification of the filler surface on properties of composites is different for each of the silicas. The obtained results are discussed in terms of effects of curvature of silica particles, surface properties, solvation cell, interphase region, viscosity changes, and morphology of the resulting composites.
  6. P. Ziobrowski, E. Andrzejewska, M. Szybowicz, A. Nowicka, M. Sadej-Bajerlein, H. Gojzewski, M. Drozdowski
    "Particle Clustering in Photocurable Nanocomposites: Dependence of Curing Kinetics and Viscoelastic Properties"
    Journal of Applied Polymer Science, 131 (2014) 39895

    Abstract

     The aim of this article is to investigate the effect of nanoparticle clustering on the mobility of nanoparticles in nanocomposites, using spectroscopic methods (Brillouin and Raman). Special attention is paid to the effect of particle clustering on photocuring kinetics. The model system was poly(2-hydroxyethyl acrylate) filled with fumed nanosilica in concentration range encompassing the percolation threshold. Results obtained from Brillouin spectroscopy show substantial changes in the sound velocity and the attenuation coefficient with increasing filler content. The damping of acoustic waves reaches the maximum at the percolation threshold (~15 wt %), which is related to changes in the mechanism of acoustic wave propagation. The formation of the cocontinuous silica phase strongly affects the curing kinetics of the monomer/silica system: the polymerization rate is the highest at a silica content corresponding to the percolation threshold. These results correlate well with the results of AFM surface roughness analysis.
  7. M. Molčan, A. Hashim, J. Kováč, M. Rajňák, P. Kopčanský, M. Makowski, H. Gojzewski, M. Molokáč, L. Hvizdák, M. Timko
    "Characterization of Magnetosomes After Exposure to the Effect of the Sonication and Ultracentrifugation"
    Acta Physica Polonica A, 126 (2014) 198-199

    Abstract

     Magnetosomes are intracellular organelles of widespread aquatic microorganisms called Magnetotactic bacteria. At present they are under investigation especially in biomedical applications. This ability depends on the presence of intracellular magnetosomes which are composed of two parts: first, nanometer-sized magnetite (Fe3O4) or greigite (Fe3S4) crystals (magnetosome crystal), depending on the bacterial species; and second, the bilayer membrane surrounding the crystal (magnetosome membrane). The magnetosomes were prepared by biomineralization process of magnetotactic bacteria Magnetospirillum Magnetotacticum sp. AMB-1. The isolated magnetosome chains (sample M) were centrifugated at speed of 100000 rpm for 4 hours (sample UM) and sonicated at power of 120 W for 3 hours (sample SM), respectively. The prepared suspensions were investigated with respect to morphological, structural and magnetic properties. The results from scanning electron microscopy showed that isolated chains of magnetosomes were partially broken to smaller ones after ultracentrifugation. On the other hand the application of the sonication process caused the formation of individual magnetosomes (unordered in chain). These results were confirmed by coercivity and magnetization saturation measurements.
  8. M. Kazmierczak, K. Pogorzelec-Glaser, A. Hilczer, S. Jurga, Ł. Majchrzycki, M. Nowicki, R. Czajka, F. Matelski, R. Pankiewicz, B. Leska, L. Kepinski, B. Andrzejewski
    "Morphology and magnetic properties of Fe3O4-alginic acid nanocomposites"
    Materials and Technology, 48 (2014) 59-62

    Abstract

     Morphology, structure and magnetic properties of nanocomposites of magnetite (Fe3O4) nanoparticles and alginic acid (AA) are studied. Magnetite Fe3O4 nanoparticles and the nanoparticles capped with alginic acid exhibit very distinct properties. The chemical bonding between alginic acid and surface of magnetite nanoparticles results in recovery of surface magnetization. On the other hand, it also leads to enhanced surface spin disorder and unconventional behavior of magnetization observed in Fe3O4-AA nanocomposites at low temperatures.
  9. R. Ranecki, M. Kamiński, M. Szybowicz, A. Dychalska, M. Błaszczyk, T. Luciński, B. Susła
    "Magnetic properties of multilayers [NI-FE/AU/CO/AU]6."
    8th International Conference - Electromagnetic Devices and Processes in Environment Protection, (2014)

    Abstract

    We present the possibility to study magnetic properties of thin magnetic films using Raman spectrometer. The method is based on the observation of standing spin waves. Experimental data are presented for Si(111)[NiFe(2nm)/ Au(2nm)/Co(0,8nm)/Au(2nm)]6 multilayers which exhibit perpendicular anisotropy of cobalt film and giant magnetoresistance.
  10. H. Maciejewski, J. Karasiewicz, M. Dutkiewicz, M. Nowicki, Ł. Majchrzycki
    "Effect of the type of fluorofunctional organosilicon compounds and the method of their application onto the surface on its hydrophobic properties"
    RSC Advances, 4 (2014) 52668

    Abstract

     Fluorofunctional silanes, polysiloxanes and silsesquioxanes were used for the modification of glass surfaces and their influence on hydrophobic properties were determined. To increase hydrophobicity of the surface, the modification was performed in two stages: (i) by a pretreatment using a silica sol (a rise in the surface roughness), and (ii) modification with the above silicon compounds. The hydrophobicity was determined by measuring the contact angle by drop profile tensiometry. The fluorocarbofunctional organosilicon derivatives examined were found to be good precursors for the synthesis of highly hydrophobic materials and coatings. In some cases the contact angles measured after surface modification exceeded 150o, i.e. they fell in the range characteristic of superhydrophobic surfaces.
  11. A. A. Poźniak, K. W. Wojciechowski
    "Poisson’s ratio of rectangular anti-chiral structures with size dispersion of circular nodes"
    Physica Status Solidi (b), 251 (2014) 367-374

    Abstract

     Using Finite Element computer simulations, Poisson’s ratio (PR) is determined for anti-chiral structures built on rectangular lattices with disorder introduced by stochastic distributions of circular node sizes. The investigated models are parameterized by the lattice anisotropy, the rib thickness, and the radii distribution of circular nodes. Three approaches are developed. The first approach, exact in the limit of infinitely large system and infinitely dense mesh, uses only planar elements (CPS3). Two other approaches are approximate and exploit one-dimensional elements utilizing the Timoshenko beam theory. It is shown that in the case of sufficiently large anisotropy of the studied structures PR can be highly negative, reaching any negative value, including those lower than −1. Thin ribs and thin-walled circular nodes favor low values of PR. In the case of thick ribs and thick-walled circular nodes PR is higher. In both cases the dispersion of the values of circular nodes radii has a minor effect on the lowest values of PR. A comparison of the results obtained with three different approaches shows that the Timoshenko beam based approximations are valid only in the thin rib limit. The difference between them grows with increasing thickness.
  12. E. Frydrych-Tomczak, B. Uszczyńska, T. Ratajczak, W. T. Markiewicz, M. Figlerowicz, M. Nowicki, H. Maciejewski, M. K. Chmielewski
    "Application of epoxy functional silanes in the preparation of DNA microarrays"
    Journal of Biotechnology, Computational Biology and Bionanotechnology, 95 (2014) 5-16

    Abstract

     Nucleic acid microarrays have recently become one of the basic techniques in the study of gene expression. Owing to progress in the field of miniaturization, thousands of oligonucleotides differing in terms of their sequences can be systematically placed on a small area of a solid support (usually glass). These probes are capable of simultaneously interacting with a large number of longer nucleic acids from particular genes. Nucleic acid microarray construction technology consists, primarily, of the appropriate functionalization of a glass surface with the use of organofunctional silanes. Oligonucleotides known as probes are attached to a functionalized surface using, for instance, the lithography technique and, after being linked to the surface, they are subjected to hybridization with complementary and labelled fragments of nucleic acids known as samples of unknown sequences. In this paper, we present a method for constructing DNA microarrays that is based on the use of microscopic slides modified with epoxy functional group-containing silanes. This study was aimed at optimizing the production of DNA microarrays. The study tested the usefulness of four different epoxy functional silanes with one or three alkoxy groups. In addition, slides were silanized with the use of alkylsilane. The glass slides were characterized using a goniometer and an atomic force microscope (AFM). The synthesized amino linker-containing oligonucleotide probes were printed onto the glass slides in order to check the effectiveness of their attachment to the solid surface.
  13. M. Molcan, A. Hashim, J. Kovac, H. Gojzewski, A. Skumiel, F. Royer, D. Jamon, P. Kopcansky, M. Timko
    "Magnetosomes - bacterial magnetic nanoparticles"
    Communications, 16 (2014) 26

    Abstract

     The magnetic properties, magneto-optical effects and hyperthermia effect were studied in solution of magnetosomes extracted from cultivated bacteria Magnetospirillum sp. AMB-1. The properties of magnetosomes were changed using different conditions during synthesis and by modification of particles after synthesis by using sonication and ultracentrifugation methods. It was shown that adding a higher amount of Wolfe’s vitamin solution (WVS) or ferric quinate (FQ) cause increase of the mean diameter from 47 nm (normal condition) up to 52 nm and 58 nm respectively. Hyperthermic measurements were performed for three types of magnetosome samples: (I) M - not influenced by separation method (long - chains magnetosomes), (II) UM - after centrifugation procedure, and (III) SM - after centrifugation procedure including sonication. The Specific Absorption Rate (SAR) decreased depending on chains shortening and decrease in hysteresis too. The SAR values were 1083, 934 or 463 W/g for the sample M, UM and SM, respectively.
  14. Ł. MajchrzyckiM. NowickiR. Czajka, K. Lota
    "Method of carbon-based electrode analysis by conductive-atomic force microscopy"
    Micro & Nano Letters, 9 (2014) 69-72

    Abstract

    A novel method of the characterisation of composite materials for electrochemical capacitor electrodes by conductive-atomic force microscopy is reported. The method allowed the analysis of the structure and the distribution of the non-conductive or less conductive additives dispersed in the carbon conductive matrix, which affect the surface conductivity of the electrodes. The composites of activated carbon with nickel (II) oxide, as well as activated carbon or carbon nanotubes with three different conducting polymers – polyaniline, poly(3,4-ethylenedioxythiophene) and polypyrrole – were prepared and tested and analysed by the reported method.

2013

  1. M. Bazarnik, J. Brede, R. Decker, R. Wiesedanger
    "Tailoring Molecular Self-Assembly of Magnetic Phthalocyanine Molecules on Fe- and Co-Intercalated Graphene"
    ACS Nano, 7 (2013) 11341-11349

    Abstract

     We investigate molecule–molecule, as well as molecule–substrate, interactions of phthalocyanine molecules deposited on graphene. In particular, we show how to tune the self-assembly of molecular lattices in two dimensions by intercalation of transition metals between graphene and Ir(111): modifying the surface potential of the graphene layer via intercalation leads to the formation of square, honeycomb, or Kagome lattices. Finally, we demonstrate that such surface induced molecular lattices are stable even at room temperature.
  2. G. Milczarek, M. Nowicki
    "Carbon nanotubes/kraft lignin composite: Characterization and charge storage properties"
    Materials Research Bulletin, 48 (2013) 4032-4038

    Abstract

    The results of this study demonstrate the spectral, microscopic and electrochemical properties of multi-walled carbon nanotubes (CNTs) surface-functionalized with kraft lignin (KL). XPS and FT-IR spectroscopy show that the biomolecule is effectively adsorbed on the surface of CNTs, leading to an increase in oxygen content and the appearance of spectral features characteristic of highly oxidized polyphenolic compounds. The presence of KL makes CNTs easily dispersible in organic (DMSO) and aqueous (0.1 M ammonia) solutions. Microscopic analysis (SEM and AFM) confirms the effective debundling of CNTs and the presence of densely packed globular structures on the surface of individual nanotubes. Deposition of the CNT/KL composite on the surface of a gold electrode facilitates its electrochemical characterization. This reveals that the CNT-supported biomolecule exhibits persistent reversible redox behavior attributed to KL-derived quinone moieties. Therefore the reversible redox activity of the lignin adsorbate can be utilized for charge storage, providing more than a 100% increase in the capacitance of KL-modified carbon nanotubes compared with unmodified ones.
  3. H. Kaczmarek, M. Nowicki, I. Vuković-Kwiatkowska, S. Nowakowska
    "Crosslinked blends of poly(lactic acid) and polyacrylates: AFM, DSC and XRD studies."
    J. Polym. Res., 20(91) (2013)

    Abstract

    The blends based on poly(lactic acid), (PLA) and polyacrylates (1:1 weight ratio) have been prepared by photopolymerization of three different multifunctional acrylate monomers (pentaerythritol triacrylate, pentaerythritol tetraacrylate and dipentaerythritol pentaacrylate) in matrix of linear PLA. The structure of these systems has been studied by Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD). It was found that the blends are highly crosslinked, rough, heterogeneous and some of them – semicrystalline. The effect of UV-irradiation on surface morphology of obtained mixtures was studied. The viscometry has been applied for measurements of changes of PLA molecular weight resulting of photodegradation. It was shown that blends are much more photostable than pure PLA.
  4. P. Wojciechowska, Z. Foltynowicz, M. Nowicki
    "Synthesis and Characterization of Modified Cellulose Acetate Propionate Nanocomposites via Sol-Gel Process"
    Journal of Spectroscopy, 2013 (2013)

    Abstract

    In this study novel organic-inorganic hybrid nanocomposites were synthesized from modified cellulose acetate propionate (MCAP) via sol-gel reaction at ambient temperature. The inorganic phase was introduced in situ by hydrolysis-condensation of tetraethoxysilane (TEOS) in different concentrations, under acid catalysis, in the presence of organic polymer dissolved in acetone. The chemical modification of CAP was monitored by infrared spectroscopy (IR). The nanocomposites structure was characterized by IR analysis and solid state 29Si NMR studies. The spectral data revealed that organic and inorganic phases are linked through covalent bound. Surface morphology of the samples and the degree of dispersion of inorganic phase in the polymer matrix were investigated using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The actual incorporation of the inorganic component into the hybrid nanocomposites was deducted from the residual weight according to thermogravimetric analysis (TGA).
  5. M. Matczak, B. Szymański, M. Urbaniak, M. Nowicki, H. Głowiński, P. Kuświk, M. Schmidt, J. Aleksiejew, J. Dubowik, F. Stobiecki
    "Antiferromagnetic magnetostatic coupling in Co/Au/Co films with perpendicular anisotropy"
    Journal of Applied Physics, 114 (2013) 093911

    Abstract

    Magnetization reversal processes in Au/Co/Au-wedge/Co/Au pseudo-spin-valve structures characterized by perpendicular anisotropy of 0.6-nm-thick Co layers were investigated by magneto-optical Kerr effect. The samples were deposited on a Ti/Au buffer layer of differing Au-layer thickness (different surface roughness and crystallite size). The distinctive influence of the buffer layer thickness on the dependences of switching fields, and energy of the effective interlayer coupling, versus Au spacer thickness is presented. In particular, increasing the buffer-layer thickness results in a decrease in the oscillation amplitude of the Ruderman–Kittel–Kasuya–Yosida-type interaction and in the enhancement of the antiferromagnetic coupling related to magnetostatic (orange peel) interactions.
  6. P. Wojciechowska, Z. Foltynowicz, M. Nowicki
    "Cellulose acetate butyrate nanocomposites synthesized via sol-gel method"
    Polimery, 58(7-8) (2013) 543-549

    Abstract

    Novel hybrid nanocomposites were synthesized from modified cellulose acetate butyrate (MCAB) via sol-gel reaction at ambient temperature. The inorganic phase was introduced in situ by hydrolysis-condensation of tetraethoxysilane (TEOS) in different concentrations, using an acid catalyst, in the presence of organic polymer dissolved in acetone. Infrared spectroscopy (IR) was used to monitor modification of CAB and nanocomposites characterization. The silica network of obtained nanocomposites was characterized by solid state Si NMR. Morphology of the samples and degree of dispersion of inorganic phase in the polymer matrix were investigated using atomic force microscopy (AFM). The organic-inorganic nanocomposites exhibit better mechanical properties than unmodified cellulose acetate butyrate

2012

  1. H. Gojzewski, M. Makowski, A. Hashim, P. Kopcansky, Z. Tomori, M. Timko
    "Magnetosomes on surface: an imaging study approach 
    SCANNING 34, 159–169, 2012

    Abstract

     In this study, we deposited isolated magnetosomes from magnetotactic bacteria Magnetospirillum strain AMB-1 onto solid surfaces using spin coating (SC) and drop coating (DC) techniques. Four imaging techniques have been used to visualize the sample structure: scanning and transmission electron microscopy (SEM, TEM), atomic and magnetic force microscopy (AFM, MFM). Additionally, dynamic light scattering was applied to measure the hydrodynamic radius of agglomerated/aggregated magnetosomes in a liquid environment. This manuscript discusses observed differences between structures obtained by two deposition techniques, i.e. possible interactions and factors responsible for magnetosomes' formation, their morphology on surfaces as a result of agglomeration and aggregation phenomena. Moreover, topography and homogeneity of obtained structures as well as thickness of protein-based membrane were also examined and described. Using high-resolution TEM, we analyzed the size of magnetic cores, their crystal structure and quality. We found that the SC technique provides a homogenous layer of magnetosomes and hydrophilization of silicon surfaces improves the deposition of magnetosomes. However, due to strong hydrogen interaction to the hydrophilic silicone surface, the organic membrane of magnetosomes is mostly flattened. As a matter of fact, the size distributions of magnetosomes deposited by SC and DC techniques (logarithmic-normal tendency) differ from the Feret diameter distribution (normal). Furthermore, our study confirms the good crystalline quality of magnetosomes' cores. It also shows that they are magnetic in the all their volume.
  2. A. Hashim, M. Molcan, J. Kovac, Z. Varchulova, H. Gojzewski, M. Makowski, P. Kopcansky, Z. Tomori, M. Timko 
    “The Influence of Morphology on Magnetic Properties of Magnetosomes” 
    ACTA PHYSICA POLONICA A 121, (2012) 1250-1252

    Abstract

    Cultivation process was changed three times. The culture medium was enriched by more amount ferric quinate (FQ magnetosomes sample) and more amounts Wolfe's vitamin solution (WVS magnetosomes sample) comparing to normal culture medium (NP magnetosomes sample). NP sample of magnetosomes shows zero coercivity and behaves superparamagnetically. The increase of coercivity (6.5 Oe for WVS and 20 Oe for FQ) may be caused by higher value of shape anisotropy and reveals stronger magnetic correlations between particles of magnetite chains.
  3. M. Oszwaldowski, S. El-Ahmar, J. Jankowski
    “Extraordinary magnetoresistace in planar configuration” 
    Journal of Physics D: Applied Physics, 45 (2012) 145002

    Abstract

    Two-dimensional (2D) planar version of the construction of an extraordinary magnetoresistance (EMR) based magnetic field sensor is proposed and verified in practice. The proposed 2D planar construction differs from the standard three-dimensional (3D) constructions by the position of the metallic shunt. In the new construction the metallic thin film of the shunt is coplanar with the sensitive semiconductor thin film. One of the advantages of that physically 2D planar construction is that it can be easily realized with the standard thin-film technology. Another advantage is that it is applicable to the preparation of EMR sensors based on the high mobility electron/hole gas confined in the new electronic materials like graphene and the topological insulator thin films both being physically 2D by nature. The validity of the planar construction is experimentally confirmed for model EMR sensors based on InSb/Ag thin films. Some interesting physical properties of those sensors are also described.
  4. S. El-Ahmar, A.A. Pozniak, J. Jankowski, M. Oszwaldowski
    “Planar construction of extraordinary magnetoresistance sensor” 
    ACTA PHYSICA POLONICA A 121, (2012) 959-962

    Abstract

    A new version: of the construction of the extraordinary magnetoresistance effect (EMR) based magnetic sensor has been proposed [2]. The differences between the original three dimensional (3D) construction and proposed 2D (planar) construction are presented. In proposed construction the metallic thin film (shunt) is coplanar with the semiconductor sensitive element. There are advantages of that planar construction like easier way of technological obtaining of the device. Another advantage is its application for EMR sensors based on new electronic materials like graphene and topological insulator thin films. The validity of the planar construction has been experimentally confirmed for model EMR sensors based on InSb/Ag structures. Comparison of the obtained experimental data with computational simulations of the EMR effect on planar model EMR sensors is performed Finite element method (FEM) is used as a tool for obtaining EMR effect simulations.
  5. J. Fickert, M. Makowski, M. Kappl, K. Landfester, D. Crespy
    “Efficient encapsulation of self-healing agents in polymer nanocontainers functionalized by orthogonal reactions” 
    Macromolecules 45, (2012) 6324-6332

    Abstract

    An orthogonal polymerization reaction between two monomers partitioned in the two liquid phases of a miniemulsion yielded nanocapsules with various functional groups (sulfonate, amine, carboxylic acid, and poly(ethylene glycol) (PEG). The formation of the nanocapsules could be realized in the presence of a self-healing agent in the liquid core. We present here the conditions for the successful preparation of functional polymer nanocapsules by free-radical polymerization as orthogonal reaction for self-healing materials. The stability of the nanocapsules was assessed by AFM measurements in the dried state as well as in water.
  6. K. Jaskiewicz, M. Makowski, M. Kappl, K. Landfester, A. Kroeger
    “Mechanical properties of poly(dimethylsiloxane)-block-poly(2- methyloxazoline) polymersomes probed by atomic force Microscopy” 
    Langmuir 28, (2012) 12629-12636

    Abstract

    Poly(dimethylsiloxane)-block-poly(2-methyloxazoline) (PDMS-b-PMOXA) vesicles were characterized by a combination of dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and atomic force microscopy imaging and force spectroscopy (AFM). From DLS data, a hydrodynamic radius of 150 nm was determined, and cryo-TEM micrographs revealed a bilayer thickness of 16 nm. In AFM experiments on a silicon wafer substrate, adsorption led to a stable spherical caplike conformation of the polymersomes, whereas on mica, adsorption resulted also in vesicle fusion and formation of bilayer patches or multilayer stacks. This indicates a delicate balance between the mechanical stability of PDMS-b-PMOXA polymersomes on one hand and the driving forces for spreading on the other. A Young’s modulus of 17 ± 11 MPa and a bending modulus of 7 ± 5 × 10–18 J were derived from AFM force spectroscopy measurements. Therefore, the elastic response of the PDMS-b-PMOXA polymersomes to external stimuli is much closer to that of lipid vesicles compared to other types of polymersomes, such as polystyrene-block-poly(acrylic acid) (PS-b-PAA).
  7. J. Jankowski, S. El-Ahmar, M. Oszwaldowski
    “On Possibility of Application of InSb-Based High-Temperature Hall Sensors for ITER Magnetic Diagnostics” 
    Proceedings of Electrotechnical Institute, 258 (2012), 149-156

    Abstract

    We report on irradiation experiments of InSb-based Hall samples at two types of neutron spectrums. One with thermal neutrons (natural neutron spectrum of fission reactor) and second with fast neutrons (filtered spectrum). Fluences in both cases reached almost 10^18 cm^-2 and that led to significant decreasing of electron mobility of samples. In case of thermal neutrons, transmutation process led to increasing of electron concentration of about 2.3×10^18 cm^-3. For samples irradiated with fast neutrons, twofold effect was observed: increase in electron concentration for samples with low carrier density and decrease in electron concentration for samples with high carrier density. All results raise important issue, that in case of ITER ex-vessel steady state sensors, research at different spectrum of neutrons are necessary.

2011

  1. J. Jankowski, S. El-Ahmar, M. Oszwaldowski,
    Hall sensors for extreme temperatures
    Sensors, 11, (2011) 876-885.

    Abstract

    We report on the preparation of the first complete extreme temperature Hall sensor. This means that the extreme-temperature magnetic sensitive semiconductor structure is built-in an extreme-temperature package especially designed for that purpose. The working temperature range of the sensor extends from -270 °C to +300 °C. The extreme-temperature Hall-sensor active element is a heavily n-doped InSb layer epitaxially grown on GaAs. The magnetic sensitivity of the sensor is ca. 100 mV/T and its temperature coefficient is less than 0.04 %/K. This sensor may find applications in the car, aircraft, spacecraft, military and oil and gas industries.
  2. H-J. Butt, M. Makowski, M. Kappl, A. Ptak
    On the adhesion between individual particles
    KONA Powder and Particle Journal 29: 53-66, 2011

    Abstract

    A dream in powder technology is to predict the structure and flow of a powder from precise knowledge of the interactions between the particles. The most important interaction is adhesion. In this paper several aspects of adhesion are discussed. First, the influence of humidity and capillary forces is analyzed. To calculate capillary forces the structure of the microcontact needs to be known with an accuracy much better than 1 nm. Determining the structure of a microcontact with such resolution is demanding, if possible at all. Considering that wear can lead to a change of the atomic structure such knowledge is practically impossible. Second, the work to break an adhesive contact depends on the effective spring constant by which the force is applied. Third, adhesion forces depend on the separation speed and not only the surface chemistry and the structure of the particles in the contact region. Fourth, we suggest to distinguish between contact and bridging adhesion.
  3. A. Ptak, H. Gojzewski, M. Kappl, H.-J. Butt
    Influence of humidity on the nanoadhesion between a hydrophobic and a hydrophilic surface
    Chemical Physics Letters, 503 (2011) 66.

    Abstract

    The adhesion force between a silicon nitride tip and a 1-dodecanethiol monolayer have been measured at different loading rates and different humidity. A way to extract the kinetic and interaction potential parameters for a single molecule interaction is demonstrated. The effect of the increase of van der Waals interaction strength per molecule with increasing humidity is explained by assuming a gradual adsorption of water into the tip surface hollows. The study should help in better understanding of the humidity effect on molecular level and in avoiding the underestimation of adhesion forces in micro- and nano-engineering in ambient conditions.
  4.  A. Dzarova, F. Royer, M. Timko,  D. Jamon, P. Kopcansky, J. Kovac, F. Choueikani, H. Gojzewski, J.J. Rousseau
    Magneto-optical study of magnetite nanoparticles prepared by chemical and biomineralization process
    Journal of Magnetism and Magnetic Materials, 323 (2011) 1453

    Abstract

    This paper deals with a magneto-optical study of suspensions of magnetosomes. These magnetosomes are synthesized by biomineralization process of magnetotactic bacteria, followed by steps of isolation and purification in order to obtain stable suspensions. The structural analysis evidences the good crystallinity of the magnetite particles with a diameter of 34 nm. Magneto-induced linear and circular anisotropy confirms the important role played by the chains in the orientation mechanism of such magnetic dipoles. Numerical adjustments of the linear anisotropy curves using a classical Langevin orientation model give the average number of magnetosomes per chain, about 12.
  5.  A. Dzarova, F. Royer, D. Jamon, P. Kopcansky, F. Choueikani, H. Gojzewski, J.J. Rousseau, M. Timko
    Optical anisotropy of magnetosome-doped polymer films
    Journal of Magnetism and Magnetic Materials, 323 (2011) 1364

    Abstract

    The anisotropy of several PVA/magnetosome magnetically textured films has been investigated. The thin film synthesized under the influence of a magnetic field (99 mT) shows the typical behavior of an anisotropic material. The results show that the magnetic field applied during the synthesis promotes an orientation of the chains of magnetosomes and permanent textured film is obtained after solidification.
  6. M. Sadej-Bajerlain, H. Gojzewski, E. Andrzejewska
    Monomer/modified nanosilica systems: Photopolymerization kinetics and composite characterization
    Polymer 52 (2011) 1495

    Abstract

    The article describes the influence of the amount and type of organically modified nanosilica (surface and structure modified Aerosil 7200 and surface-modified Aerosil R711) on the photopolymerization kinetics of tetraethylene glycol dimethacrylate and on the physical properties of nanosilica dispersions in the monomer and the polymer matrix. Kinetic measurements showed that silica addition can accelerate or retard the polymerization depending on the silica content; the magnitude of this affect depends on the type of silica modification and can be associated with stability of silica dispersion (as measured by Zeta potential value). The highest reactivity showed compositions containing 4-5 wt.-% of silica and acceleration of the polymerization seems to result mainly from the increase in the propagation rate coefficient. The composites obtained show a uniform dispersion of nanoparticles within the polymer matrix for the silica content at least several wt.-%. The size of aggregates covered with the polymer layer is between 50 and 150 nm for Aerosil R7200 and 75-300 nm for Aerosil R711.
  7. M. Bazarnik, J. Henzl, R. Czajka, K. Morgenstern
    Light driven reactions of single physisorbed azobenzenes
    Chemical Communications, 47 (2011) 7764.

    Abstract

    We present a successful attempt of decoupling a dye molecule from a metallic surface via physisorption for enabling direct photoisomerization. Effective switching between the isomers is possible by exposure to UV light via the rotation pathway.
  8. W. Koczorowski, M. Bazarnik, R. Czajka
    "SPM Characterization of Titanium Disilicide Nanostructures Grown on a Ni-Modified Si(100) Substrate"
    Acta Physica Polonica A 120 (2011) 480

    Abstract

    The paper presents our recent investigations of the early stage growth of titanium silicides on a modified Si(100) substrate. The substrate was modified by deposition of a minute amount of Ni atoms, and the subsequent flash annealing. This process led to the creation of parallel defect lines on the Si(100) surface. We expected TiSi2 to form elongated structures on top and/or between the defect lines. Though this idea failed, stable nanostructures were observed and characterized using scanning probe microscopy (scanning tunneling microscopy and atomic force microscopy) methods.

2010

  1. J. Gutek, A. Kosiorek, R. Czajka, K. Kempa and M. Giersig
    Study of the Electron Tunnelling in Single-Barrier Nanostructures Using the Conductive Atomic Force Microscopy
    Journal of Advanced Microscopy Research 5, (2010), 1.

    Abstract

    We study a direct electron tunnelling in nanostructures consisting of two conductive materials separated by a thin nonconductive film. Triangle-shaped gold islands, formed on a natively-oxidized silicon substrate by means of nanosphere lithography (NSL), form the top electrodes of these metal-native oxide-silicon nanostructures. We employ the conductive atomic force microscopy (C-AFM) to characterize electronic and topographical properties of these nanostructures. The resulting maps of the current distribution through the nanostructure array reveal, geometrical as well as local physical properties of the native oxide film (thickness, dielectric integrity, etc.).
  2. W. Koczorowski, M. Bazarnik, M. Cegiel, A. Petroutchik, A. Wawro, R. Czajka
    STM/STS characterization of platinum silicide nanostructures grown on a Pt(111) surface
    Applied Surface Science 256, (2010),  4215.

    Abstract

    Formation of the platinum silicides nanostructures and their electronic properties have been studied using scanning tunneling microscopy and scanning tunneling spectroscopy. The investigated structures have been grown by solid state epitaxy upon deposition of the Si atoms (coverage about 0.2 ML) and sequential annealing at temperature range 600-1170 K. The formation of the Pt2Si and PtSi islands was investigated until the Si atoms embedded into the Pt substrate at the 1170 K. The images of the silicides structures and Pt substrates with atomic resolution have been recorded. The evolution of the spectroscopic curves both for substrates and nanostructures, corresponding to the structural and sizes changes, have been shown.
  3. H. Gojżewski, M. Kappl, A. Ptak, and H.-J. Butt
    Effect of Humidity on Nanoscale Adhesion on Self-Assembled Thiol Monolayers Studied by Dynamic Force Spectroscopy
    Langmuir, 26(3), (2010), 1837.

    Abstract

    The adhesion force between silicon nitride tips of an atomic force microscope and different self-assembled thiol monolayers (SAMs) was measured at different loading rates and humidity. SAMs were formed from HS(CHynCHj with n = 6.8,9,10,15and.HS(CH2)nOH with n = 6,9,11,16. With a special setup, the loading rate could be increased to 107 nN s -1. For the interaction with two-dimensional crystalline CH 3-terminated. SAMs (n ≥ 8), two regimes can be distinguished. At loading rates below 104-105 nN s-1, the adhesion force increased proportional to the logarithm of the loading rate. Adhesion is most likely dominated by van der Waals attraction. At higher loading rates, the adhesion forces increased steeper with the logarithm of the loading rate. The specific process limiting separation is not yet identified. On OH-terminated SAMs, the adhesion force was ∼6 times higher than on the CH3-terminated SAMs, even at low humidity. This can partially, but not fully, be explained by hydrogen bridges forming between the hydroxyl groups of the monolayer and silanol groups of the tip. For relative humidity above 10%, the capillary force further increased the adhesion force, which reached a maximum at values of relative humidity between 40% and 80%. Adhesion force versus loading rate (Fad versus rF) curves increased roughly linearly over the whole range of loading rates, The slope depended on the humidity and it is correlated with the absolute strength of the capillary force.
  4. A. Ptak, H. Gojzewski, M. Kappl, H.-J. Butt
    Quantitative Analysis of the Interaction between an Atomic Force Microscopy Tip and a Hydrophobic Monolayer
    Journal of Physical Chemistry C, 114 (2010) 21572

    Abstract

    Atomic force microscopy has become an important technique for studying the adhesion of nanometer-sized contacts. However, there is still no good method to quantitatively characterize adhesive interactions. With a modified atomic force microscope, adhesion forces between a silicon nitride tip and a self-assembled monolayer of 1-dodecanethiol on gold(111) have been measured at different loading rates. Adhesion force-versus-loading rate curves revealed two regimes. Various interpretations of the two-regime character, like the existence of an inner transition state in the interaction potential or rebinding processes, are discussed. An explanation related to the cooperativity of individual van der Waals bonds responsible for effective adhesion is proposed. A way to extract the kinetic and interaction potential parameters for an individual van der Waals bond is demonstrated using a microscopic model to the analysis of adhesion force-versus-loading rate dependence.
  5. A. Ptak, M. Makowski, M. Cichomski
    Characterization of nanoscale adhesion between a fluoroalkyl silane monolayer and a silicon AFM tip. Complex character of the interaction potential
    Chemical Physics Letters, 489 (2010) 54

    Abstract

    Using a modified atomic force microscope, the nanoadhesion between a silicon tip and a monolayer of 1H, 1H, 2H, 2H-perfluorodecyl trichlorosilane was measured at different loading rates. The adhesion force versus loading rate curve could be fitted with two logarithmic terms. The application of a model of thermally activated escape from a bound state to the analysis of the curves made it possible to extract quantitative information about the effective adhesion potential. Although only van der Waals interactions appear to make a major contribution to the nanoadhesion, the interaction potential characterizing the nanoadhesion still has a complex, two-transition state character.
  6. M. Timko, A. Dzarova, J. Kovac, P. Kopcansky, H. Gojzewski
    The Effect of Polymer Immobilization on Magnetic Properties of Magnetosomes
    Acta Physica Polonica A, 118 (2010) 995.

    Abstract

    The anisotropy of several PVA/magnetosomes magnetically textured films has been investigated from the point of view of magnetic properties. The thin film synthesized under the influence of a magnetic field (99 mT) shows the typical behavior of an anisotropic material. On sample textured in magnetic field the magnetization loop measurements were performed in dependence on the direction of the external magnetic field with respect to the texture axis. The results of hysteresis measurements show that the magnetic field applied during the synthesis promotes an orientation of the chains of magnetosomes and permanently textured film is obtained after solidification. The obtained values for magnetic remanence and coercivity were dependent on the external magnetic field orientation and the alignment effect of particle moments may be clearly seen which is in agreement with the theoretical model of magnetic particle chains.
  7. B. Strzelczyk, W. Kempiński, M. Wróblewski, B. Susła, J. Piekoszewski, Z. Werner, M. Barlak, J. Martinek, M. Błaszyk, Sz. Maćkowiak, Z. Trybuła, Sz. Łoś and M. Kempiński
    Low Temperature STM/STS, Standard AFM and XPS of Local MgBx Phases
    Acta Physica Polonica A, 118 (2010) 417.

    Abstract

    Low temperature scanning tunneling microscopy/ scanning tunneling spectroscopy, room temperature atomic force microscopy and X-ray photoelectron spectroscopy of the boron ions implanted into the magnesium substrate were performed in order to get information about the local superconducting behavior of thin MgBx film. Results confirm the island superconductivity far from the percolation threshold of the bulk superconducting MgB2 sample.
  8. T. Runka, R. Diduszko, M. Berkowski, M. Kamiński, A. Łapiński, M. Połomska and M. Drozdowski
    Characterization of tetragonal SAT0.3: LA0.075:CAT0.625 perovskite crystal: spectroscopic andmicroscopic investigations”
    J. Raman Spectrosc., 41, (2010), 1030.

    Abstract

    We report room temperature measurements of X-ray diffraction (XRD), optical transmission microscopy (OTM), atomic force microscopy  (AFM),  infrared-absorption (IR), and micro-Raman spectroscopy  (µ-RS) of  the oriented SAT0.3: LA0.075:  CAT0.625 single crystal. The final structure refinement of SAT0.3: LA0.075: CAT0.625  crystal was performed for I4/m space group at room temperature. Vibrational spectra of the crystal were discussed in terms of group-theoretical predictions for untilted (Fm3m) and tilted tetragonal (I4/m) perovskite structure. The confocal µ-Raman measurements of depth profiling of SAT0.3: LA0.075: CAT0.625  crystal suggest a relationship between sensitivities of the ordering-related Raman-active modes and the variation of order parameter η.

2009

  1.  M. Cegiel, M. Bazarnik, R. Czajka
    STM investigation of cobalt silicide nanostructures’ growth on Si(111)-(√19x19)
    Cent. Eur. J. Phys. 7(2), (2009), 295.

    Abstract

     Continuing miniaturization of electronic devices necessarily requires assembly of several different objects or devices in a small space. Therefore, besides thin films growth, the possibility of fabricating wires and dots [1, 2] at the nanometre scale composed of metal silicides is of the top interest. This report is about the STM/STS investigation of cobalt silicides' nanostructures created on Si(111)-(19×19) substrates via Co evaporation and post deposition annealing. This (19×19) reconstruction was induced by Ni doping. Less than 1ML of Co on surface was obtained. Surface reconstruction induced growth of agglomerates of clusters rather than an uniform layer. The post deposition annealing of a crystal sample (up to 670 K, 770 K, 870 K, 970 K, 1070 K and 1170 K) led to creation of silicides' nanostructures. Measurements showed that coalescence of Co nanoislands begun around 970 K. Annealing above 1070 K led to alloying of a Co, Ni and Si. As a consequence the Si(111)-(7×7) reconstruction occurred at the cost of Si(111)-(19×19).
  2.  M. Bazarnik, J. Dąbrowski, R. Czajka
    MFM Investigations of [NiFe/Au/Co/Au]N Multilayers
    Acta Phys. Polon. A 115(1), (2009), 220.

    Abstract

    Magnetic force microscopy measurements combined with computer simulations were applied to investigate the strengths of magnetic field over the [NiFe/Au/Co/Au]N multilayers with in-plane and out-of-plane anisotropy observed for NiFe and Co layers, respectively. All measurements were performed in air atmosphere at room temperature. Dimensions and density of magnetic domains were estimated. The distribution of magnetization directions was deduced from comparison of magnetic force microscopy with the simulation results. Some sort of modulation in stray magnetic field was observed, but till now it is of unknown origin.
  3. M. Bazarnik, M. Cegiel, P. Biskupski, M. Jazdzewska, S.Mielcarek, M. Sliwinska-Bartkowiak, R.Czajka
    STM/STS investigation of carbon nanotubes deposited on Bi2Te3 surface
    Cent. Eur. J. Phys. 7(2), (2009), 291.

    Abstract

    This paper reports our scanning tunneling microscopy and spectroscopy (STM/STS) study of double-walled and multi-walled carbon nanotubes (CNTs) of different diameter deposited on Bi2Te3 (narrow gap semiconductor). The approximate diameter of the studied double-walled and multi-walled CNTs was 2 nm and 8 nm, respectively. Crystalline Bi2Te3 was used as a substrate to enhance the contrast between the CNTs and the substrate in the STS measurements performed to examine peculiarities of CNT morphology, such as junctions, ends or structural defects, in terms of their electronic structure.
  4. M. Timko, A. Dzarova, J. Kovac, P. Kopcansky, H. Gojżewski, A. Szlaferek, Magnetic
    Properties of Bacterial Nanoparticles
    Acta Phys. Polon. A 115(1), (2009), 381.

    Abstract

    A suspension of bacterial magnetosomes was investigated with respect to structural and magnetic properties and hyperthermic measurements. The mean particle diameter of about 35 nm was confirmed by transmission electron microscopy (TEM), X-ray and magnetic analysis. The X-ray powder diffraction peaks of magnetosomes fit very well with standard Fe3O4 reflections. The found value for specific absorption rate (SAR) of 171 W/g at 5 kA/m and 750 kHz means that magnetosomes may be considered as good materials for the biomedical applications in hyperthermia treatments. Moreover, they have biocompatible phospholipid membrane.
  5. H. Gojżewski, A. Richter, D. Wróbel, A. Apostoluk, P. Siejak, P. Raimond
    Growth of thin polymer films containing side-chain azo-dye analyzed by atomic force microscopy
    Surface Science 603, (2009), 237.

    Abstract

    Thin films containing both the azo-dye disperse red 1 (DR1) and the poly(methylmetacrylate) (PMMA) or the poly(phenylenevinylene) (PPV) are deposited by Langmuir-Blodgett and spin coating techniques on various substrates. The morphology, surface structure and growth pattern of the azo-dye-polymers were studied by atomic force microscopy. Nucleation and growth processes are responsible for the generation of different structures. The spin coated films were additionally oriented using the electric field poling method (corona poling). The film homogeneity is improved by this method in all cases. Due to the polar character of DR1 molecules, rod-like sub-structures are observed after the corona poling process in DR1-MMA films. The indium tin oxide surface enhances reorientation of the azo-dye-polymer molecules during corona poling and results in a significant reduction of the surface roughness.
  6. A. Ptak, M. Kappl, S. Moreno-Flores, H. Gojzewski, and H.-J. Butt
    Quantitative Characterization of Nanoadhesion by Dynamic Force Spectroscopy
    Langmuir 25 (1), (2009) 256.

    Abstract

    We present a method for the characterization of adhesive bonds formed in nanocontacts. Using a modified atomic force microscope, the nanoadhesion between a silicon nitride tip and a self-assembled monolayer of 1-nonanethiol on gold(111) was measured at different loading rates. Adhesion force-versus-loading rate curves could be fitted with two logarithmic terms, indicating a two step (two energy barrier) process. The application of the Bell-Evans model and classical contact mechanics allows the extraction of quantitative information about the effective adhesion potential and characterization of the different components contributing to nanoadhesion.
  7.  M. Timko, An. Dzarova a, J. Kovac, A. Skumiel, A. Jozefczak, T. Hornowski, H. Gojzewski , V. Zavisova, M. Koneracka, A. Sprincova,O. Strbak, P. Kopcansky, N.Tomasovicova
    Magnetic properties and heating effect in bacterial magnetic nanoparticles
    Journal of Magnetism and Magnetic Materials 321, (2009),1521.

    Abstract

    A suspension of bacterial magnetosomes was investigated with respect to structural and magnetic properties and hyperthermic measurements. The mean particle diameter of about 35 nm was confirmed by transmission electron microscopy (TEM), X-ray and magnetic analysis. The X-ray powder diffraction peaks of magnetosomes fit very well with standard Fe3O4 reflections. The found value for specific absorption rate (SAR) of 171 W/g at 5 kA/m and 750 kHz means that magnetosomes may be considered as good materials for the biomedical applications in hyperthermia treatments. Moreover, they have biocompatible phospholipid membrane.
  8. A. Richter, E. Czerwosz, P. Dłużewski, M. Kozłowski, M. Nowicki
    Nanoindentation of heterogeneous carbonaceous films containing Ni nano-crystals
    Micron 40, (2009), 94.

    Abstract

    Composite films of nano-size nickel grains embedded in a carbonaceous matrix are synthesized by a PVD process of C60 fullerenes and Ni acetate. The morphology of the nano-composite films is characterized by TEM, selected area electron diffraction, chemical analysis and AFM. Correlations with deposition parameters and typical structure changes are found. The mechanical properties are analyzed by nanoindentation. The load-displacement charts show typical pop-ins correlated with the heterogeneous nano-structure. The depth dependent hardness and indentation modulus vary according to the nano-composite structure and reflect the changes of the mechanical properties in the film.
  9. M. Hermanowicz, A. Jezierski, J. Kaczkowski and D. Kaczorowski
    Electronic Structure of Ternary Antimonides YbPdSb
    Acta Phys. Pol. A, vol. 115 (2009) 226-228.

    Abstract

    In this paper we present the electronic structure and magnetic properties of YbPdSb in low-temperature MgAsAg-type structure and high-temperature TiNiSi-type structure. The calculations were performed by ab initio full-relativistic full potential local orbital method within the local spin density approximation. Ab initio calculations showed the metallic character of YbPdSb compound in both structures. The density of states at the Fermi level is greater in high-temperature than in low-temperature structure.
  10. M. Szorcz, B. Idzikowski, M. Wawrzyniak, M. Kamiński, and B. Susła
    Conductance Quantization in Co-Ag alloy nanocontacts
    Acta Physicae Superficierum vol. XI, (2009), 123.

    Abstract

    In this paper we present the electronic structure and magnetic properties of YbPdSb in low-temperature MgAsAg-type structure and high-temperature TiNiSi-type structure. The calculations were performed by ab initio full-relativistic full potential local orbital method within the local spin density approximation. Ab initio calculations showed the metallic character of YbPdSb compound in both structures. The density of states at the Fermi level is greater in high-temperature than in low-temperature structure.

2008

  1. M. Cęgiel, M. Bazarnik, P. Biskupski, S. Winiarz, J. Gutek, A. Boś, S. Suto, S. Mielcarek, A. Wawro and R. Czajka
    STM study of titanium silicide nanostructure growth on Si(111)-(√19x√19) substrate
    Applied Surface Science , (2008), 6948.

    Abstract

    We have performed an STM/STS study of titanium silicide nanostructures grown on Si(111)-(√19×√19) substrate by Ti evaporation and post-deposition annealing. The (√19×√19) reconstruction was induced by Ni doping. The reaction between the deposited material and the substrate at 220 K was radically different from that observed in the case of the standard Si(111)-(7×7) substrate, as evidenced by the different evaporation time necessary to obtain a comparable coverage of the surface. The annealing was accomplished by direct heating of a crystal sample (up to 520 K, 670 K and 970 K). Measurements showed that coalescence of Ti nanoislands began between 520 K and 670 K. Annealing above 900 K led to alloying of Ti, Ni and Si. As a consequence, Si(111)-(7×7) reconstruction occurred at the cost of Si(111)-(√19×√19).
  2. A. Wawro, S, Suto, R. Czajka, A. Kasuya
    Solid state reaction of Fe with Si (111) vicinal surface: splitting of bunched steps
    Nanotechnology (20), (2008), 205706. 

    Abstract

    The solid state reaction of deposited Fe (four monolayers, ML) with vicinal Si(111) substrate induced by subsequent thermal treatment has been studied using scanning tunnelling microscopy. At the lower range of annealing temperatures up to 400°C the bunched steps of bare substrate are reproduced by the surface of the covering iron silicide layer. At 400°C the onset of three-dimensional growth of iron silicide islands is observed. In comparison to the samples covered with smaller amounts of Fe it appears at a lower annealing temperature. Above 500°C the bunched steps split into lower ones but more densely distributed due to proceeding reactions between Fe-rich iron silicide and Si substrate. As a consequence, at 700°C the well-developed three-dimensional nanocrystallites of iron silicide are randomly distributed on the Si surface. This observation is in contrast to the formation of a regular array of iron silicide crystallites upon deposition of 2 ML of Fe.
  3. A Richter, M. Nowicki, B Wolf
    A Nanoindentation Study of Photo-Induced Changes in Polymers Containing Azobenzene
    Molecular Crystals and Liquid Crystals, 483, (2008), 49.

    Abstract

    Irradiation of materials by light of suitable photon energy can cause structural alterations of either permanent or temporary character that are reflected in their mechanical properties. Nanoindentation is particularly well suited to characterise small representative volume elements of materials with gradual or discrete changes of their mechanical properties. It is, therefore, an ideal technique for investigation of thin films, nanocomposites and other specimens with inhomogeneities in the nanometer to micrometer length scale that are either inherently existing in the material or externally stimulated. In this article, nanoindentation was applied to study the mechanical properties of pDR1 m surface relief gratings containing azobenzene. Hardness and elastic modulus increase after and during irradiation of the pDR1 m film correlated with an increase in the polymer density after light exposure. Permanent structural changes in the pDR1 m film are related to crosslinking and photo-isomerisation. In-situ nanoindentation under controlled periodic light illumination exhibits a week photomechanical switching and results finally in a permanent stiffer polymer network.
  4. M. Wróblewski, M. Kamiński, B. Susła
    Nanometrology of HOPG (0001) and Au(111) Surface Topography Using STM
    Elektronika - Konstrukcje, Technologie, Zastosowania , 2008-5.

    Abstract

    In this paper we presented the problem of measurement uncertainty in nanoscale. We showed the calibration problem of scanning tunneling microscope (STM) based on an example of highly oriented pyrolitic graphite (HOPG) and thin layers of gold Au(111) studies. The emphasize was put on interpretation of STM images.
  5. M. Kamiński, M. Wróblewski, B. Susła
    The Measurement of YBa2Cu3O7-δ Single Crystals Using the Atomic/Magnetic Force Microscopy
    Acta. Phys. Polon. 114, (2008), 91.

    Abstract

    In this paper the experimental investigations of the YBa2Cu3O7-δsingle crystal, using atomic force microscopy and magnetic force microscopy, are presented. The atomic force microscopy was used to identify oxidized and unoxidized YBa2Cu3O7-δcrystal. The YBa2Cu3O7-δsingle oxidized crystal was examined for magnetic properties by means of magnetic force microscopy. The research was carried out at a room temperature and in the air atmosphere without external magnetic field.

2007

  1. S. Winiarz, W. Polewska, R. Czajka
    STM/STS investigations of titanium oxide nanostructures on Au substrate
    Materials Letters , (2007), 4818.

    Abstract

    Au substrate was prepared by Au evaporation on Si(111) surface. Au surface was composed of Au grains with typical diameter of about 50 nm with atomically flat terraces. TiO2 nanostructures were created by electron gun evaporation of Ti while simultaneous dosing of high purity O2 gas. The pressure of oxygen was kept at 5 · 10- 8 mbar and controlled by means of residual gas analyzer (RGA). Scanning tunneling microscopy (STM) images showed that TiO2 nanocrystallites had grown between Au grains in cavities between them. This may suggest that such spots are preferred TiO2 nucleation sites. I-V curves measured above Au showed metallic properties while those measured above TiO2 exhibit energy gap characteristics for semiconducting material.
  2. S. Winiarz, P. Biskupski, S. Szuba, S. Mielcarek and R. Czajka
    STS investigations of metallic nanostructures deposited on Bi2Te3
    Surface Review and Letters.  (3), (2007), 357.

    Abstract

    Bi2Te3 has attracted attention due to its potential applications in the microfabrication of integrated thermoelectric devices. It is also interesting to study the metallization process of this compound. Metallic nanostructures were deposited by means of an electron gun evaporator in ultra high vacuum (UHV) conditions (10-8 Pa) on the freshly cleaved 0001 surface of the crystal Bi2Te3. Measurements were conducted using the commercially available Omicron UHV scanning tunneling microscope (STM). Scanning tunneling spectroscopy (STS) measurements were performed using current imaging tunneling spectroscopy (CITS), and subsequent calculation of the dI/dV maps. Metallic characteristics were observed on nickel islands since early stages of the growth. CITS and dI/dV maps showed distinct contrast between the substrate and metallic islands. Similar contrast was not observed in the case of titanium, most probably due to an intercalation process. Occurring of such a process was confirmed by the appearance of the superlattice structure.
  3. H. Kato, T. Taoka, S. Nishikata, G. Sazaki, T. Yamada, R Czajka, A. Wawro, K. Nakajima, A. Kasuya, and S. Suto
    Preparation of an Ultraclean and Atomically Controlled Hydrogen-Terminated Si(111)-(1 x 1) Surface Revealed by High Resolution Electron Energy Loss Spectroscopy, Atomic Force Microscopy, and Scanning Tunneling Microscopy: Aqueous NH4F Etching Process of Si(111)

    Abstract

    Japanese Journal of Applied Physics , No. 9A, (2007), 5701.
    We propose an improved wet chemical process for preparing a high-quality hydrogen-terminated Si(111)-(1×1) surface and show an atomically ordered and ultraclean surface without carbon and oxygen contamination. The vibrational properties and surface morphology are investigated by high-resolution electron energy loss spectroscopy (HREELS), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The HREELS spectra and images of AFM and STM reveal the precise aqueous NH4F etching process of Si(111) and indicate the high controllability of steps and terraces at the atomic scale. The surface cleanliness and morphology strongly depend on the etching time. At the etching time of 10min, we obtain an ultraclean and atomically ordered surface with wide terraces of 36 ±7nm step distance. It is confirmed by AFM and STM that 1.0% ammonium sulfite is useful for removing dissolved oxygen in the 40% NH4F etching solution and for preparing a high-quality H:Si(111)-(1× 1) surface with a low density of etch pits. The onset of tunneling current and the gap of 1.39 eV are measured by scanning tunneling spectroscopy. There is no peak at -1.3 eV in comparison with the previous report [Phys. Rev. Lett. 65 (1990) 1917].
  4. M. Kamiński, M. Wróblewski, M. Cęgiel, B. Susla
    The Study of Electron Properties of Carbon Nanotubes Deposited on HOPG Using Scanning Probe Spectroscopy
    Acta. Phys. Polon. A Vol. 111, No 5, (2007), 661.

    Abstract

    In this paper we present experimental investigations of carbon nanotubes deposited on highly orientated pyrolytical graphite using scanning tunneling microscopy and scanning tunneling spectroscopy. The aforementioned methods apart from detailed topographic data provided us with information about local density of state. We also show the I-V and dI/dV characteristics, which display the metallic and semiconducting characters of investigated carbon nanotubes. All measurements were taken in the air and at room temperature.
  5. A. Richter, H. Gojżewski, J. J. BelBruno
    Visco-elastic properties of thin nylon films using multi-cycling nanoindentation
    Int. J. of Mat. Res.98(5), (2007), 414.

    Abstract

    Time dependent behavior of thin nylon films is investigated by depth sensing nanoindentation. Different loading rates and holding times are applied in single indentation procedures to study the relaxation behavior of nylon resulting in a characteristic nonlinear displacement-time dependence. Several load-time functions of multi-cycling indentation are developed, such as constant load repetition and incremental load increase mode sometimes containing holding segments. Hysteresis loops in multi-cycling nanoindentation quantify the visco-elastic energy of nylon films. The loading rate does not change the loop size if the maximum and minimum load of the cycle are the same. The unloading process has to be sufficiently large to allow the performance of the visco-elastic relaxation of the material.
  6. A. Skumiel, M. Labowski, H. Gojzewski
    The Heating Effect Of The Magnetic Fluid Apg-832 In An Alternating Magnetic Field
    Molecular and Quantum Acoustics vol. 28, (2007), 229.