Papers by Keyword: Lattice Parameters

Abstract: In this work we investigate and analyze phase composition and structure parameters of the nanocomposites obtained by the melt-based impregnation of porous opal matrices with dielectrics prospective for optoelectronics applications Bi₁₂GeO₂₀ and NaBi (MoO₄)₂. The embedded material is formed inside opal pores as nanocrystals with an average linear size not exceeding 50 nm and modified lattice parameters. In the case of impregnating opals with Bi₁₂GeO₂₀, new additional compounds are produced and transformation of opal matrix from amorphous to crystalline state is observed. These effects are discussed in the framework of the interaction of bismuth cations with the surface of the 285 nm SiO₂ particles that compose opal matrix. No stoichiometry deviations and new phases are detected in “opal-NaBi (MoO₄)₂” composite.

Abstract: The effects of heating temperature in the range 790-990 ° C and subsequent cooling in the water, in air, with the furnace on the formation of the structure, phase composition of the titanium alloy VST2 were studied. There was the metastable β-solid solution and α - phase during the quenching heating temperature to 865 °C. The phase composition in the temperature range of 865-915 °C was α + β + α''. There was only α'' - martensite in the structure at the temperatures above 940 °C. Reducing the rate of cooling (air, furnace) helped the retention of two-phase α + β - state after all the heating temperatures. The temperature - rate parameters of heat treatment which can obtain good strength and ductility properties are suggested.

Abstract: Preliminary study on Na-doped LiNi_1/3Mn_1/3Co_1/3O₂ was carried out to investigate possibility substitution Li with Na. Samples were prepared using modified solid state synthesis route. X-ray diffraction (XRD) results show that the most optimum synthesis temperature for parent composition x=0 in Li_1-xNa_xNi_1/3Co_1/3Mn_1/3O₂ was 900°C. Solid solution limit for Na-doped LiNi_1/3Mn_1/3Co_1/3O₂ is x < 0.2 (or 20% Na). For x ≥ 0.2 in Li_1-xNa_xNi_1/3Co_1/3Mn_1/3O_2, a secondary phase of sodium cobalt oxide (Na_0.6CoO₂) start to exist. Furthermore, at x ≥ 0.4, the secondary phase became a dominant phase in Li_1-xNa_xNi_1/3Co_1/3Mn_1/3O₂.