Микроструктура и фазовый состав сплава дисилицидов железа и хрома

The phase composition, microstructure, and interphase interfaces of the disordered CrSi2-FeSi2 solid solution obtained by spontaneous crystallization (before and after annealing) have been investigated by scanning, transmission electron microscopy, electron diffraction, and X-ray energy dispersive spectrometry. The as-grown samples contained the phases of CrSi2 with the P6422 hexagonal structure and FeSi2 with the P4/mmm tetragonal structure. Annealing of the samples led to the phase transformation of tetragonal FeSi2 into the orthorhombic modification Cmca. Precipitates of cubic iron monosilicide FeSi with space group P213, nano-precipitates of Si and silicon silicide Cr5Si3 with a tetragonal structure I4/mcm were observed inside the FeSi2 grains. Impurities of interstitial Cr atoms with a concentration up to 2.0 at% are found in iron (di)silicides grains in all samples. The structure of the CrSi2 phase remains unchanged after annealing; the concentration of impurity iron atoms is about 0.7 at%. Orientation relationships between the crystal lattices of the phases are established and strains due to the mismatch of the crystal lattices are determined.

Влияние режима получения образцов и термообработки на локальную структуру халькогенидного полупроводника Ge-=SUB=-2-=/SUB=-Sb-=SUB=-2-=/SUB=-Te-=SUB=-5-=/SUB=-

Specifics of "amorphous state - crystal" phase transitions in dependence on the samples obtaining method and thermal processing, as well as changes in the structure and close range order in the arrangement of the atoms of Ge20Sb20.5Te51 chalcogenide semiconductors have been studied by the x-ray diffraction and Raman spectroscopy. It has been shown that Ge20Sb20.5Te51 films obtained by thermal evaporation on an unheated substrate are amorphous; after heat treatment at 220 and 400 °C, transform into a crystalline phase with a cubic and hexagonal structure. The chemical bonds and the main structural elements that form the matrix of the investigated objects, as well as the changes that occur in them during heat treatment, have been determined.

Properties of ZnS1-xFe x thin Films Deposited

Semiconducting ZnS1-xFex thin films were prepared with different substrate temperature on glass substrates from aqueous solution technique. ZnS1-xFex films were prepared, using a aqueous solution containing ethyleneglycol, zinc chloride and sulphur. XRD study shows that the aqueous deposited ZnS1-xFex thin films are polycrystalline hexagonal structure. The effect of Fe concentration on the optical parameters such as absorption coefficient, refractive index, dielectric function, optical conductivity, and reflectivity is also investigated. Results revealed that Cd1-xFexS is a suitable compound for spintronics and optoelectronics devices. A good optical transparency of about 75% in the visible region is observed for all prepared ZnS1-xFex thin films. The direct optical band gap of the deposited ZnS1-xFex thin films with different substrate temperature (380°C – 530°C) were lying in the range 3.27–3.35 eV.

Mechanical Stability, Electronic And Magnetic Properties Of Half- Heusler FeCrAs Alloy For Spintronics Application

The search for functional materials in spintronic devices has become a major component of material research in recent times. The structural, elastic, mechanical, electronic and magnetic properties of half-Heusler FeCrAs alloy (HHFCA) have been examined adopting spin-polarized density functional theory calculations. Our result shows that the hexagonal structure is the high pressure phase of the FeCrAs alloy while the half-Heusler structure is the more stable phase at ambient pressure. Also, the HHFCA is mechanically stable and exhibits half-metallic ferromagnetism besides an indirect band gap in the minority spin channel. The total magnetic moment in one formula unit of the alloy is 1.00 μB, in agreement with the Slater-Pauling rule and the bulk of the magnetic moment contributed by the Cr atoms. Furthermore, high Curie temperature of ~ 1000 K has been obtained for the HHFCA which suggests that it is a promising material for spintronic applications.

Comparative Investigation on Micro-Structural, Morphological, Optical, Magnetic and Anti-Microbial Traits of Undoped and Nickel-Incorporated Zinc Oxide Nanoparticles

The main objective of the present work is to synthesize pure and nickel doped zinc oxide nanoparticles by facile co precipitation technique. The work is confined to study the effect of various weight ratios (0.3, 0.6 ,0.9) % Nickel into Zinc oxide and to witness the drastic changes that occur in its various physical properties such as structural, optical, magnetic from X ray diffraction (XRD), UV visible (ultra violet) spectra, VSM (Vibrating sample magneto meter). XRD analysis reveals the wurtzite hexagonal structure and it is also found that as the doping concentration increases the crystallite size decreases from 4.6 nm to 3.0 nm. SEM results depicts the agglomeration of the particle, the synthesized samples shows both rod and flakes formation when the doping concentration is increased. Morphological changes were analysed TEM (Transmission electron microscope). The enhancement in the optical behaviour were observed and the energy band gap is calculated with the data obtained from UV-Visible spectra and the optical properties shows a tremendous increase as the Ni content increases which proves the sample a suitable candidate for solar cells and photovoltaic devices. Purity of the prepared sample were investigated through EDAX analysis. The hysteresis loop from the VSM analysis elucidate the saturation magnetization and the ferromagnetic behaviour of the sample. X-ray Photoemission Spectroscopy results indicates the presence of several oxygen species adsorbed on the surface. The study is also extended to analyse its anti-microbial effect against Staphylococcus aureus. The cell culture dish of the sample showed a notable resistance against Staphylococcus aureus when the concentration of nickel is increased and could be extended to pharmaceutical applications in treating several skin infections.

Morphological and structural characterization of Pb:ZnS nanostructure films deposited by simple thermal evaporation

ZnS nanostructure films were deposited by a thermal evaporation method. Two films were prepared; the first was zinc sulfide (undoped ZnS) and the second was Pb-doped zinc sulfide (Pb:ZnS). X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) techniques were employed to investigate the element contents of the two films; they were found to be stoichiometric. Surface and growth evolution of films were explored by SEM images and found to have morphological development from spherical forms into nanostructure lookalike Taraxacum erythrospermum (Dandelion) with increasing the Pb from 0 wt.% to 12 wt.%. A structural study was performed using XRD patterns. The films have ZnS hexagonal structure (002) preferential orientation with various Pb percentages. In the doped sample, ZnS nanostructure and pores and nanowires (NWs) were formed with a mean diameter less than 50 nm; the undoped film had dense structure and was thin. This study illustrated the influence of Pb doped on the morphological modification of ZnS films.

Promising Cr-Doped ZnO Nanorods for Photocatalytic Degradation Facing Pollution

Chromium (Cr)-doped zinc oxide (ZnO) nanorods with wurtzite hexagonal structure were prepared through a thermal decomposition technique. The concentration effect of the Cr doping on the structural, morphological, and optical properties of the ZnO nanorods was established by correlating various measurements: transmission electron microscopy (TEM), photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and several UV-visible studies. The obtained nanorods were investigated as photocatalysts for the photodegradation process of methyl orange (MO), under UV-vis light illumination. Different weights and time intervals were studied. A 99.8% photodegradation of MO was obtained after 100 min in the presence of 1 wt.% Cr III acetate hydroxide and zinc acetate dehydrate “ZnO-Cr1”. The kinetic rate constant of the reaction was found to be equal to 4.451 × 10−2 min−1 via a pseudo-first order rate model. Scavenger radicals demonstrated the domination of OH• radicals by those of O2•− superoxide species during the photodegradation. The interstitial oxygen site Oi is proposed to play a key role in the generation of holes in the valence band under visible irradiation. The ZnO-Cr1 photocatalyst displayed good cycling stability and reusability.

Tuning The Properties of Ba-M Hexaferrite BaFe11.5Co0.5O19: A Road Towards Diverse Applications

The development of hexaferrite nanoparticles is scrutinized as potential sorbents for the removal of chromium (Cr) ions from aqueous chromium-containing solutions in a batch adsorption experiment. The transition metal Co doped BaFe12O19 hexaferrite compounds (BHF) have been synthesized successfully via citrate auto combustion technique. Structural, morphological, and magnetic properties are testified. X-ray diffraction pattern ratifies the existence of hexagonal phase as a main phase for the prepared samples. The average crystallite sizes are found in the range of 47–49 nm. The high-resolution transmission electron microscopy (HRTEM), as well as the Fourier, transform infrared spectrophotometry results confirm an M-type hexagonal structure existing. The c-T indicates the temperature-dependent ferromagnetic behavior of BHF nanoparticles. The derivative shows a single transition temperature Tc at 698 °C, 710 for BHF and BHCF respectively. The prepared samples are utilized as an adsorbent for the removal of Cr (VI) from the aqueous solution. The maximum adsorption capacity (qm) of Cr (VI) on the nano hexaferrite is higher than that of various other adsorbents testified in the literature. The pseudo-second-order kinetic model gives a better fit to the experimental data

Effect of Zinc (Zn) -Doped on the Structural, Optical and Electrical Properties of (Cdo)1-Xznx Films Prepared by Pulsed Laser Deposition Technique

Pure cadmium oxide films (CdO) and doped with zinc were prepared at different atomic ratios using a pulsed laser deposition technique using an ND-YAG laser from the targets of the pressed powder capsules. X-ray diffraction measurements showed a cubic-shaped of CdO structure. Another phase appeared, especially in high percentages of zinc, corresponding to the hexagonal structure of zinc. The degree of crystallinity, as well as the crystal size, increased with the increase of the zinc ratio for the used targets. The atomic force microscopy measurements showed that increasing the dopant percentage leads to an increase in the size of the nanoparticles, the particle size distribution was irregular and wide, in addition, to increase the surface roughness of the nanoparticles. An increase in the zinc ratio also led to a decrease in the energy gap. While the Hall effect measuring showed an increase in the concentration of charge carriers and a decrease in their mobility with increasing the doping ratio.

Effect of Yb3+ doping level on the structure and spectroscopic properties of ZnO optical ceramics

Zinc oxide optical ceramics with hexagonal structure doped with 0.6 –5.0 wt% Yb were fabricated by uniaxial hot pressing of commercial oxide powders at 1180 °C in vacuum. The ceramics were characterized by X-ray diffraction, SEM, EDX, X-ray and optical spectroscopy. It is shown that Yb3+ ions are distributed between C-type Yb2O3 sesquioxide crystals and ZnO grain boundaries. The Yb3+ doping of ZnO ceramics enhances the near-band-edge emission of zinc oxide. ZnO:Yb optical ceramics are promising for optoelectronic applications.