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1
Content available remote

Hydroquinone Synthesis of Silver Nanoparticles from Silver Bromide Suspensions

100%
Król-Gracz A., Nowak P., Michalak E., Dyonizy A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
196-199
EN
The results of research into the preparation of silver nanoparticles using photoreduction in the presence of hydroquinone as the reductant were discussed. Substrates for the synthesis of silver nanoparticles were ultrafine crystalline gelatine-stabilised aqueous suspensions of silver bromide. The influence of the reductant to substrate molar ratio and the medium's pH to the efficient production of silver nanoparticles were studied. The properties of resultant silver particles were examined using UV-Vis spectroscopy. Transmission electron microscopy was used for the photomicrography of silver nanoparticles suspensions.
2
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The Effect of Carbon Coating on the Electrochemical Performance of Nanosized Li_2FeSiO_4 Cathode Materials

80%
Wang Y., Su D., Wang G.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
279-282
EN
Carbon-coated Li_2FeSiO_4/C cathode materials have been synthesized through a modified ball-milling process. The physical characterizations of Li_2FeSiO_4 were conducted by using X-ray powder diffraction, field-emission scanning electron microscopy and transmission electron microscopy techniques. Field-emission scanning electron microscopy and transmission electron microscopy images revealed that Li_2FeSiO_4/C consists of nanosized particles coated with an amorphous carbon layer. The electrochemical performances of Li_2FeSiO_4/C cathode materials were evaluated through fully assembled lithium batteries via cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy. The Li_2FeSiO_4/C cathode materials showed a much improved electrochemical performance in terms of higher specific capacity, better cycling performance and less charge transfer resistance than that of the pristine Li_2FeSiO_4.
3
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Kinetics of Solid-State Synthesis of Quaternary Cu₂FeSnS₄ (Stannite) Nanocrystals for Solar Energy Applications

80%
Baláž P., Baláž M., Zorkovská A., Škorvánek I., Bujňáková Z., Trajić J.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
1153-1155
EN
In this study we demonstrate the use of elemental precursors (Cu, Fe, Sn, S) to obtain stannite forms by a solid-state one-pot mechanochemical synthesis. In the processing route, we report the kinetics of the synthesis. For the characterization of the unique nanostructures, X-ray diffraction, specific surface area measurements and SQUID magnetometry methods were applied. CFTS polymorphs with the tetragonal body-centered structure with the average crystallite size 18-19 nm were obtained. The weak ferromagnetic properties of the quaternary nanocrystals after maximum milling time were also documented.
4
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Microstructural Study of Fe-Si(Ge)-Nb-Cu-B Finemet Alloys

80%
Michalik S., Bednarcik J., Brzózka K., Sovak P., Górka B.
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issue 5
818-819
EN
Structural changes in Finemet based alloys invoked by germanium replacement for silicon were investigated using the X-ray diffraction, the X-ray absorption spectroscopy and the Mössbauer spectroscopy. Ge substitution preserves a nanostructural character of annealed samples at temperature 550°C; specifically the formation of a DO_3-type with about 19 at.% of (Si,Ge) was confirmed. The mean size of nanocrystals was estimated to be about 7 nm.
5
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Study of Silicon Nanocrystals Formation in Annealed Amorphous In Situ Nitrogen Doped Silicon Thin Films Obtained by Low Pressure Chemical Vapor Deposition

80%
Bouridah H., Haoues H., Beghoul M., Mansour F., Remmouche R., Temple-Boyer P.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
175-177
EN
In this work, we investigate the formation of silicon nanocrystals in annealed low pressure chemical vapor deposition in situ nitrogen doped silicon thin films (SiN_x) obtained at low temperature (465°C) by using a mixture of disilane (Si_2H_6) and ammonia (NH_3). Results show that nitrogen content in films plays an important role in defining the obtained films morphology in terms of crystallites sizes and their distribution. Indeed, according to the nitrogen content introduced in films, the crystalline state of films varies from a submicron crystalline structure to a nanocrystalline structure. An average silicon nanocrystalline size of 10 nm was obtained for film with x = 0.07 nitrogen content, annealed under a temperature of 850C during 2 h.
6
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Positron Lifetimes in Zirconia-Based Nanomaterials

80%
Procházka I., Čížek J., Kuriplach J., Melikhova O., Konstantinova T., Danilenko I.
Acta Physica Polonica A
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2008
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vol. 113
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issue 5
1495-1499
EN
Positron lifetime spectroscopy is employed in a comparative study of several zirconia-based materials: (i) the pressure-compacted nanopowders of the three zirconia polymorphs - pure ZrO_2 (monoclinic), yttria-stabilized ZrO_2+3 mol.% Y_2O_3 (tetragonal) and yttria-stabilized ZrO_2+8 mol.% Y_2O_3 (cubic), (ii) ceramic materials obtained by sintering of the above two yttria-stabilized zirconia nanopowders and (iii) the tetragonal and cubic yttria-stabilized zirconia monocrystals. Positron lifetime data observed on the nanopowders suggest that the two shortest components, exhibiting lifetimes of ≈180 and ≈370 ps, arise from the annihilation of positrons trapped in defects associated with grain boundaries, presumably the vacancy-like defects and tripple points, respectively. Positron lifetime spectra observed on the ceramic materials resemble those found for the corresponding monocrystals, giving thus an additional support to the above interpretation of the nanopowders results.
7
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Surface Chemistry of Zirconia Nanopowders Doped with Pr_2O_3: an XPS Study

80%
Suchorski Y., Wrobel R., Becker S., Opalińska A., Narkiewicz U., Podsiadly M., Weiss H.
Acta Physica Polonica A
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2008
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vol. 114
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issue S
S-125-S-134
EN
Zirconia nanopowders of tetragonal crystallographic structure doped with Pr_2O_3 were prepared by the microwave-assisted hydrothermal synthesis and coprecipitation method. The surface compositions were studied by X-ray photoelectron spectroscopy. The nanopowder particles appear to be inhomogeneous in their structure: for the surface region an enrichment with praseodymium is detected by X-ray photoelectron spectroscopy measurements. This allows the assumption of a core-shell-like structure of single nanopowders particles. The X-ray photoelectron spectroscopy studies confirm also Zr^{4+} and Pr^{3+} as main oxidation states of zirconium and praseodymium in the studied compounds.
8
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Study of Ultrathin In-Ag Layers οn Tungsten by Means of Surface Spectroscopy Techniques

80%
Bukaluk A., Trzcinski M., Okulewicz K.
Acta Physica Polonica A
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2008
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vol. 114
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issue S
S-17-S-28
EN
Auger electron spectroscopy, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, scanning tunnelling microscopy, low energy electron diffraction, and thermodesorption methods were used to investigate the process of growth of ultrathin In films and formation of In-Ag surface alloys on tungsten substrate. Several indium layers, having coverage ranging from 0.2 to 0.8 ML were deposited on tungsten substrate in room temperature. It was found that at the lowest coverages (Θ= 0.1-0.3 ML) indium atoms form (3×1) structure, characterized by very sharp low energy electron diffraction patterns. With increasing Θ they tend to form densely packed islands interpreted as slightly distorted In(111) monolayers. Surface diffusion of In onto the tungsten surface was studied by using ESCA imaging property of SCIENTA ESCA200 instrument. Measuring the photoelectron intensity as a function of two spatial coordinates and the energy, we observed movement of In atoms on the tungsten surface. On the basis of the change of surface coverage with distance surface the diffusion coefficient was evaluated at the temperature range of 400-700 K. Intermixing of ultrathin films of indium and silver, after their surface diffusion from the sample edges to the centre of the tungsten surface, were observed by using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and the Auger electron spectroscopy methods. Intermixing was controlled by means of photoemission spectra from the valence states and the In 4d level, as well as by X-ray photoelectron spectroscopy studies of indium and silver core levels excited by Al K_α source.
9
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Effect of Annealing Time on Structure of Fe_{72.5}Cu_{1}Nb_{2}Mo_{2}Si_{15.5}B_{7} Alloy

80%
Nemcová V., Girman V., Hrabčáková V., Michalik Š., Bednarčík J., Almáši M., Sovák P.
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vol. 126
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issue 1
116-117
EN
The process of a primary crystallization of the Fe_{72.5}Cu_{1}Nb_{2}Mo_{2}Si_{15.5}B_{7} alloys was investigated by differential thermal analysis (DTA), x-ray diffraction (XRD) and transmission electron microscopy (TEM). Amorphous ribbons were isothermally annealed for 0.5, 2, 6, 30 and 150 minutes at 520 °C. Both, the XRD and TEM study showed that the level of devitrification of the sample increases with the annealing time. The above mentioned techniques confirmed the presence of the nanocrystalline grains of the Fe_{3}Si phase and enable us to study the evolution of the identified phase.
10
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Combustion Formation of Novel Nanomaterials: Synthesis and Cathodoluminescence of Silicon Carbide Nanowires

80%
Savchyn V., Karbovnyk I., Popov A., Huczko A.
Acta Physica Polonica A
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2009
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vol. 116
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issue S
S-142-S-145
EN
This paper presents the combustion synthesis and characterization of one-dimensional silicon carbide nanostructures (nanowires of 3C-SiC polytype with zincblend structure) by means of cathodoluminescence technique. Cathodoluminescence spectra of nano-SiC samples and, as a reference, of a commercially available SiC micropowder are compared. It is shown that the emission band at 1.97 eV which is slightly evidenced in the spectrum of the commercial SiC under 10 keV electron beam irradiation becomes the prevailing band in CL of the purified silicon carbide nanowires.
11
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Influence of Zn on Structure and Magnetic Properties of Rapid Quenched (Fe-Zn)-Cu-Nb-Si-B Alloys

80%
Kolesar V., Michalik S., Kovac J., Girman V., Sovak P., Kollar P.
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issue 5
790-791
EN
The aim of this work was to study the influence of Zn on the formation of nanostructure in Fe_{73.5 - x}Zn_xCu_1Nb_3Si_{13.5}B_9 (x = 1, 3, 5) ribbons prepared by the melt-spinning technique. X-ray diffraction measurements proved amorphous state of the sample with x = 1. The sample with x = 3 contains a small fraction of Fe_3Si phase and the sample with x = 5 is in nanocrystalline state with the average grain size of about 25 nm. The reduced radial distribution function G(r) was calculated for local structure investigation. Increasing Zn content enhances crystallization during solidification which leads to increase of magnetocrystalline anisotropy and consequently to increase of coercivity.
12
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Finemet Thin Films Substituted by Chromium - CEMS and MOKE Study

80%
Brzózka K., Szumiata T., Sovák P., Górka B., Hibner K., Balcerski J.
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issue 5
794-796
EN
Conversion electron Mössbauer spectroscopy and magneto-optical Kerr effect were applied to investigate hyperfine interactions and macroscopic magnetic properties of Finemet-type thin films. Phase analysis as well as compositional evolution of hyperfine parameters and coercivity was performed in the range of chromium percentage 0 ≤ x ≤ 14. Essential differences in structure and hyperfine parameters were found for films of different chromium concentration. Coercivity shows non-monotonic dependence with minimal value at x = 5.
13
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Influence of Temperature and Time on Nd_2O_3-SiO_2 Composite Prepared by the Solgel Process

80%
Duhan S., Aghamkar P.
Acta Physica Polonica A
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2008
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vol. 113
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issue 6
1671-1677
EN
Using solgel method Nd_2O_3-SiO_2 binary oxide systems were prepared. The binary oxide transformed from the amorphous phase to nanocrystalline phase upon heat treatment in air. Characterization of the Nd_2O_3-SiO_2 was carried out by using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effect of the sintering temperature and time on the evolution of the binary oxide system was discussed. It is found that sintering time plays a pivotal role to obtain Nd_2O_3-SiO_2 nanocomposite. At temperature of 900°C, the sample was sintered for 12 h and monoclinic Nd_2O_3 nanocrystallites, with average crystallite size ≈12 nm, were obtained.
14
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Positronium Probing of Pores in Zirconia Nanopowders

80%
Prochazka I., Cizek J., Lukac F., Melikhova O., Hruska P., Anwand W., Liedke M., Konstantinova T., Danilenko I.
Acta Physica Polonica A
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2017
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vol. 132
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issue 5
1564-1567
EN
In the present paper, conventional positron lifetime measurements on selected zirconia-based nanopowders are reported. The nanopowders were doped with various metal cations (Y³⁺, Eu³⁺, Gd³⁺, Lu³⁺ and Mg²⁺). Lifetime experiments were conducted in air and supplemented with mass density measurements. In a range of lifetimes, from a few ns to ≈70 ns, up to two individual lifetime components could be identified. Such observations confirmed positronium (Ps) formation with subsequent ortho-Ps pick-off annihilation as well as the occurrence of pores of different size. Pore sizes were estimated using a shape-free model of the correlation between pore size and ortho-Ps lifetime. The origins of pores are discussed on the basis of the ortho-Ps data in combination with the results of mass density measurements.
15
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Optical and Structural Properties of Cu Doped ZnS Nanocrystals: Effect of Temperature and Concentration of Capping Agent

80%
Hasanzadeh J.
Acta Physica Polonica A
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2016
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vol. 129
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issue 6
1147-1150
EN
We have provided the Cu doped zinc sulfide (ZnS:Cu) nanoparticles using a wet chemical synthesis. In principle, the nanoparticles are provided by mixing the reactants in a double distilled water solvent. We have used the mercaptopropionic acid as the capping agent. We have obtained the physical properties of the nanoparticles using the methods: UV absorption, photoluminescence spectroscopy, and X-ray diffraction analysis. The average size of nanoparticles is obtained in the range 3-6 nm. In addition, the X-ray diffraction pattern of ZnS:Cu nanoparticles reveals a zinc-blende crystal structure at room temperature.
16
Content available remote

Defects in Zirconia Nanomaterials Doped with Rare-Earth Oxides

80%
Prochazka I., Cizek J., Melikhova O., Konstantinova T., Danilenko I.
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vol. 125
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issue 3
760-763
EN
Positron lifetime and coincidence Doppler broadening measurements on ZrO_2+3 mol.% RE_2O_3 (RE = Eu, Gd, Lu) nanopowders and ceramics obtained by sintering these nanopowders are reported. The initial nanopowders were prepared by a co-precipitation technique and exhibited a mean particle size of ≈ 15 nm. The nanopowders were calcined and pressure-compacted. All compacted nanopowders exhibited the prevailing tetragonal phase with at most 15% of the monoclinic admixture. Positrons in compacted nanopowders were found to annihilate almost exclusively at grain boundaries: (i) vacancy-like misfit defects along grain boundaries and (ii) larger defects situated at intersections of grain boundaries (triple points). In nanopowders, a small portion of positrons formed positronium in pores between crystallites. Sintering of nanopowders at 1500C caused a substantial grain growth and formation of ceramics. Sintering-induced grain growth led to a disappearance of the triple points and pores. The ceramics containing Eu and Gd dopants consist of mixture of the monoclinic and the tetragonal phase, while the ceramics with Lu dopant exhibits almost exclusively the tetragonal phase.
17
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Simulation of Positron Annihilation Response to Mechanical Deformation of Nanostructured AgCo

80%
Melikhova O., Kuriplach J., Čížek J., Procházka I., Hou M., Pisov S., Zhurkin E.
Acta Physica Polonica A
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2008
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vol. 113
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issue 5
1455-1464
EN
Nanostructured materials attract nowadays a broad attention due to their specific properties. Defects play an essential role in material properties so their characterisation is very important. The evolution of the various open volume defects in AgCo nanowire modelled samples obtained using molecular dynamics was studied. Isothermal and isoenergetic deformation mechanisms are considered. General analyses of open volume defects concerning their size and their chemical environment were performed. Positron lifetimes, binding energies, and high momentum parts of the momentum distribution of annihilationγ-quanta were calculated for selected defects.
18
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Microstructure and Surface Morphology of Nanocrystalline Silver Silicates

80%
Duhan S.
Acta Physica Polonica A
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2012
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vol. 121
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issue 3
636-638
EN
Microstructure and surface morphology of AgO nanocrystallites (25 nm) supported on SiO_2 and subjected to heat treatment in air up to 500C have been studied by transmission electron microscopy, scanning electron microscopy, and the Fourier transform infrared spectroscopy measurements. It has been found that heating at 500C resulted in spreading of AgO over silica and formation of quasi two-dimensional amorphous phase (silicate precursor) exhibiting very weak band at 566 cm^{-1} have appeared in the Fourier transform infrared spectroscopy. Nanocrystalline silver silicate of undefined structure formed at 300-500C.
19
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Structural and Optical Characterizations of~Ge Nanostructures Fabricated by~RF Magnetron Sputtering and Rapid Thermal Processing

70%
Abd Rahim A., Hashim M., Rusop M., Jumidali M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
16-19
EN
In this work, we use a simple and cost effective technique of sputtering followed by the rapid thermal processing at 900C for 30 s to form Ge nanostructures on the Si(100) substrate. A layer of Ge (300 nm) and Si cap layer (100 nm) were deposited using RF magnetron sputtering. Two samples were prepared: Ge layer with Si capping (Si/Ge/Si) and Ge layer without Si capping (Ge/Si). Scanning electron microscopy shows that subsequent annealing in a rapid thermal processing gives uniformed Ge or SiGe islands with an estimated size of 100-500 nm. For the Ge/Si sample, under post growth annealing there had vanished the deposited Ge layer as confirmed by energy dispersive X-ray analysis. Atomic force microscopy shows that the surface roughness increases by a factor of 15.55% as the islands formed. The Raman spectrum shows that good crystalline structures of the Ge and SiGe peaks are produced. High resolution X-ray diffraction reveals cubic and tetragonal Ge phases with estimated average crystallite sizes of 42 nm and 20 nm, respectively. The results showed that it is possible to grow high quality Ge and SiGe nanostructures using a simple technique of sputtering for potential applications in photonics and high speed devices.
20
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Structure and Morphology of Gold Nanoparticles in Solution Studied by TEM, SAXS and UV-Vis

70%
Murawska M., Skrzypczak A., Kozak M.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
888-892
EN
Gold nanoparticles have a great number of applications, among others in material sciences, biology and medicine. A method for the synthesis of gold nanoparticles in solution with the use of gemini surfactant was proposed and the nanoparticles obtained were subjected to thorough characterisation. The method proposed is a modification of the Turkevich method, based on reduction of tetrachloroauric acid in the presence of trisodium citrate and a dicationic (gemini) surfactant - 1,1'-(1,4-butan)bis(3-dodecyloxymethylimidazolium) di-propionate. Morphology and size distribution of gold nanoparticles obtained were examined by the transmission electron microscopy (TEM), UV-Vis spectroscopy and small angle scattering of synchrotron radiation (SAXS). The plasmon resonance of the nanoparticles obtained was observed in the wavelength range corresponding to the presence of gold nanoparticles with sizes ranging from 5 to 100 nm. TEM images confirmed that the spherical shape of nanoparticles was dominated in reference solutions prepared of sodium citrate and tetrachloroauric acid. In the solutions prepared with addition of gemini surfactant, the gold nanoparticles of triangular morphology were observed.
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