Solid State Phenomena Vol. 310

Abstract: Synthesis of YSAG:Yb ceramic powders with different stoichiometry by chemical precipitation method was carried out. It has been established that scandium can replace both dodecahedral and octahedral positions of garnet. It is shown that scandium is embedded in those positions that become available to it when the YAG:Yb composition deviates from stoichiometric. Thus, scandium can compensate for the lack of one of the components of the oxide composition Y₂O₃, Yb₂O₃, and Al₂O₃ during the formation of the garnet phase.

Abstract: Ferroelectric ceramic solid solutions Li_xNa_1-xTa_yNb_1-yO₃ (х = 0.17; у = 0 – 0.5) with the perovskite structure have been obtained by the thermobaric synthesis method. Particularities of their microstructure, elastic properties, electrical conductivity and permittivity have been researched. It has been established that an increase in the thermobaric synthesis temperature leads to a decrease in the Young’s modulus value. Specific static conductivity values have been determined; charge carrier activation enthalpies Н_а have been calculated. The Curie temperature of the samples has been determined to decrease with an increase in tantalum content. A Ferroelectric ceramic solid solution Li_0.17Na_0.83Ta_0.1Nb_0.9O₃ was shown to undergo four structure phase transitions in the temperature range 300-820 К. A Li_0.17Na_0.83Ta_0.1Nb_0.9O₃ has been shown to be a high temperature superionic. Possible mechanisms of the detected phenomena are discussed.

Abstract: The influence of hydrostatic pressure on the binding energy of hydrogenic impurity state in a wurtzite Al_yGa_1-yN/Al_xGa_1-xN parabolic quantum well and GaN/Al_xGa_1-xN square quantum well are studied using the variational method. The ground-state binding energies are presented as the functions of hydrostatic pressure, well width, composition and impurity center position. The anisotropic properties of the parameters in the system, and the changes (dependence) of electron effective mass, the dielectric constant, band gap with pressure and coordinate are considered in the numerical calculations. The results show that the hydrostatic pressure has obvious influence on the binding energy. The binding energy increase slowly with increasing the hydrostatic pressure p and the composition x, while the binding energy decrease significantly with increasing the well width and the position of impurity center. It is seen that the changing trends of the binding energy as a function of well width, pressure and the composition in the Al_yGa_1-yN/Al_xGa_1-xN parabolic quantum well are basically the same with that in the GaN/Al_xGa_1-xN square quantum well, but the changing trends of the binding energy as a function of impurity center position in the Al_yGa_1-yN/Al_xGa_1-xN parabolic quantum well are significantly greater than that in the GaN/Al_xGa_1-xN square quantum well.

Abstract: Tb (oct-phe)₃·H₂O and Eu (oct-phe)₃·H₂O were prepared by chemical reaction in solution. The molecular formula of the complex was determined by elemental analysis and FT-IR. The optical properties of rare earth complexes were further tested by ultraviolet-visible-infrared absorption measurements. The results show that the optical absorption performance is better in the wavelength range of 200-300 nm. The luminescent properties of the rare earth complexes in the wavelength range of 450-750 nm were tested. It was found that the rare earth (Eu, Tb) complexes of octylphenylalanine have good luminescent properties.

Abstract: The electronic and magnetic properties of palladium hydrogen are investigated using first-principles spin-polarized density functional theory. By studying the magnetic moments and electronic structures of hydrogen atoms diffusing in face-centered cubic structure of transition metal Pd, we found that the results of magnetic moments are exactly the same in the two direct octahedral interstitial site-octahedral interstitial site diffusion paths-i.e. the magnetic moments are the largest in the octahedral interstitial site, and the magnetic moments are the lowest in saddle point positions. We also studied on the density of states of some special points, with the result that the density of states near the Fermi level is mainly contributed by 4d electrons of Pd and the change of magnetic moments with the cell volume in the unit cell of transition metal Pd with a hydrogen atom.

Abstract: Yttrium (III) complexes of Acylaminocarboxylates (N-octanoyl-alaninates, N-octanoyl-phenylalaninate, N-octanoyl-serinates) were prepared by chemical reaction method in methanol solution. The abbreviation of these yttrium (III) complexes were Y(oct-ala)₃, Y(oct-phe)₃ and Y(oct-ser)₃ respectively. These complexes were characterized by elemental analysis, XRD, FT-IR, ¹H NMR, UV-Vis and UV-Vis diffuse reflection. WAXD and SAXS profiles show the amorphous structure of the yttrium complexes. FT-IR and ¹H NMR spectrum establish the molecular formula, functional group information and coordination structure of the yttrium complexes. The optical absorption properties were investigated by UV-Vis and UV-Vis diffuse reflection spectrum.

Abstract: Submicron-sized calcium carbonate (CaCO₃) particles were prepared using an aerosol method in which two commercial air humidifiers containing 0.05 M of Na₂CO₃ and CaCl₂ aqueous solutions were utilized as aerosol suppliers. Two streams of aerosols evaporated from the separate humidifiers were allowed to meet in 17-meter long, spiral reaction tube where collisions between two types of droplets containing precursor reagents leaded to grow of CaCO₃ particles and precipitate onto the inner walls. XRD and SEM analysis revealed that CaCO₃ particles were formed in calcite phase almost entirely.

Abstract: The paper studies applicability of individual particles of Ag-Cu nanoalloys as data bits in the next generation memory devices constructed on the phase change memory principle. To fulfill this task, the structure formation was simulated with the molecular dynamics method on cooling from the melt of Ag-Cu nanoparticles of the diameter of 2.0 – 8.0 nm of different chemical compositions (with copper content in the alloy from 10 to 50 percent), based on the modified tight-binding potential (TB-SMA). The authors investigated the influence of the size effects and the heat removal rate on the formation of the clusters structure. The investigation showed that different internal structures can be developed upon cooling from the liquid phase, so there were determined some criteria of their stability. Clusters with copper content of not more than 10% and diameters of more than 6.0 nm were isolated from the entire set of the considered particles.

Abstract: A method was developed for synthesis of a single phase lithium tantalate charge doped by rare earth elements (TR) from highly pure solutions containing tantalum. The method is based on obtaining and thermal treatment of citrate precursor containing Li, Ta and TR. Charge samples were obtained due to suggested technological scheme; the dopant had given concentration and was chemically uniformly distributed. The charge can be applied both in single crystal growing technology and at obtaining of functional ceramics based on LiTaO₃:TR.