Nano Hybrids and Composites Vol. 28

Abstract: The Cd₃As₂+MnAs composite with 20 mole % of MnAs has been studied complexly in a wide ranges of temperatures, pressures and magnetic fields. Negative magnetic resistance has been found in the sample. This anomalous behavior is considered as a result of changes in tunneling processes due to reduce of distance between magnetic moment of ferromagnetic and structural transitions caused by pressure.

Abstract: Regularities of change of electrophysical properties of glasses S87-2, S78-4, S78-5, applied in electronic optics had been studied. The correlation between structural changes and electrical conductivity is established. A comparative analysis of the electric current influence on the new phase formation and the time to achieve phase equilibrium in the glasses is carried out.

Abstract: Studies of the temperature dependence of the electrical properties of glasses show that the high-temperature annealing in glasses observed irreversible processes. These processes lead to changes in electrical conductivity, dielectric permittivity, and hence the electrical capacitance, dielectric loss tangent, and other parameters. Obviously, this is due to structural changes in the glass as a result of high-temperature annealing. In this regard, this paper presents studies of structural and phase transformations in glasses used for the production of microchannel plates in the process of high-temperature annealing in vacuum and in the air atmosphere at different times. The studies were conducted by x-ray phase and X-ray diffraction analysis, as well as X-ray fluorescence elemental analysis.

Abstract: In this article, the influence of structural and phase changes on the thermoelectric properties of PbTe doped with CdSe compounds of various molar concentrations were studied. The research showed that with a minimum value of the lattice parameter of the formed new phases in the PbTe matrix (at an impurity concentration of 0.5 mol%), the specific electrical conductivity and thermoEMF coefficient have a minimum value. A further increase in concentration leads to an increase in these parameters.

Abstract: The effect of Li and Sr impurities on the kinetics and structure formation of alloys in the Sn - Pb, In - Zn, Sn - Zn systems used in the soldering of instrument nodes in electronics has been investigated. The XPS method showed that under the given experimental conditions and the indicated concentrations of lithium impurities in lead and strontium in zinc, there are no prerequisites for the formation of chemical compounds, which is explained by an insignificant impurity content, although a significant amount of chemical compounds is formed according to state diagrams. It was also established that impurities affect the kinetics of phase growth in the junction zone.

Abstract: Influence of small additives of copper, silver and tin on the angle of wetting and work of adhesion of monocrystals of chlorides of potassium and sodium is considered. The nature of interphase interaction of limit of the section monocrystals of chlorides of sodium and potassium with additives of the specified metals is revealed.

Abstract: Cd_xPb_1-xS films with a thickness of 620 and 680 nm were prepared by chemical precipitation from a reaction mixture containing lead salt, thiourea, alkali and cadmium acetate. The concentration of cadmium acetate was 0.01 and 0.1 mol/l. Electron-microscopic studies showed a fundamental difference in the morphology of the Cd_xPb_1-xS thin films with a 10-fold difference in the concentration of cadmium acetate in the reaction bath. The results of energy dispersive analysis indicate the nonstoichiometry of the synthesized films on sulfur. Auger spectrometry revealed a high content of oxygen in the surface layer of the thin film coating Cd_xPb_1-xS (up to 10 and 40 at. %). In the sample obtained from the reaction bath containing 0.01 mol / l of cadmium acetate, after ion etching at a depth of more than 30 nm, no oxygen was detected. In a sample prepared with a cadmium acetate content of up to 0.1 mol/l, the oxygen content does not exceed 3 at. %

Abstract: This article discusses the effect of annealing time at temperatures of 400 and 500 ° C on the electrophysical properties of CuO films prepared by the sol-gel method based on isopropyl alcohol, copper acetate and diethylamine. The film thickness was 440 nm. Phase composition, electrical resistance, conductivity type, optical properties of films are determined.

Abstract: During low-temperature annealing, the segregation of the alloying element leads to a strong enrichment of the surface layer, causing a rearrangement of the surface electron structure. This change in the electron structure is manifested in the characteristic energy loss spectra. Annealing of single crystals at 400–500 K leads to an increase in the density of surface electron states. As shown by the calculations of the surface potential using experimental data on the temperature dependence of the surface concentration, dopant segregation causes a linear increase in the surface potential.