We have fabricated Mn-doped Bi 2 Te 3 and Sb 2 Te 3 single crystals by the vertical gradient solidification method. The compositions and crystal structures of Bi 2-x Mn x Te 3 and Sb 2-x Mn x Te 3 were determined using Electron Probe Micro-Analyzer (EPMA) and powder X-ray diffraction (XRD) patterns, respectively. Both crystal structures were rhombohedral with smaller lattice constants because of the smaller atomic radius of Mn than those of Bi and Sb. Based on the magnetization measurements, Mn-doped Bi 2 Te 3 and Sb 2 Te 3 compounds have ferromagnetic ordering at T C = 10 and 17 K, respectively.

Inside evaporating two-component sessile droplets, a family of the Rayleigh convection exists, driven by salinity gradient formed by evaporation of solvent and solute. In this work, the characteristic of the flow inside an axisymmetric droplet is investigated. A stretched coordinate system is employed to account for the effect of boundary movement. A scaling analysis shows that the flow velocity is proportional to the (salinity) Rayleigh number (Ras) at the small-Rayleigh-number limit. A numerical analysis for a hemispherical droplet exhibits the flow velocity is proportional to the non-dimensional number \documentclass[12pt]{minimal}\begin{document}$Ra_s^{1/2}$\end{document}Ras1/2, at high Rayleigh numbers. A self-similar condition is established for the concentration field irrespective of the Rayleigh numbers after a moderate time, and the flow field is invariant with time at this stage. The scaling relation for the high Rayleigh numbers is verified experimentally by using aqueous NaCl droplets.

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Bi2Te3 thermoelectric thin films were deposited on the flexible polyimide substrates by RF magnetron co-sputtering of a Bi and a Te targets. The influence of the substrate temperature and RF power on the microstructure, chemical composition, and the thermoelectric properties of the sputtered films was investigated by using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and in-plane resistivity/Seebeck coefficient measurement. It was shown that the thermoelectric properties of the films depend sensitively on the Bi/Te chemical composition ratio and the substrate temperature, and the layered structure was clearly observed from the cross section of the (00L)-oriented, nearly stoichiometric Bi2Te3 films when the substrate temperature is higher than 250 °C. As-deposited Bi2Te3 films deposited at 300 °C show the highest power factor of 0.97 mW/K(2)m and the Seebeck coefficient of -193 μV/K at 32 °C, which also have (00L) preferred orientation and the layered structure. The durability of the Bi2Te3 films on polyimide against repeated bending was also tested by monitoring the film resistance, and it was concluded that the Bi2Te3 films are applicable reliably on the curved surfaces with the radius of curvature larger than 5 mm.

Colloidal silica/silane sol solutions were prepared in variation with the amount of silane and reaction time. Such sol solutions were synthesized from colloidal silica/tetramethoxysilane(TMOS)/methyltrimethoxysilane (MTMS). Sol solutions were prepared by sol-gel method through two step reactions. In order to understand their physical and chemical properties, dip coating of sol solutions was performed on the glass substrates. The effects of amount of MTMS and reaction time on the formation of coating films were studied. Coating films became transparent as the reaction time increased. Contact angle of coating films increased with increasing the amount of MTMS. Contact angle of coating films decreased with increasing reaction time. Surface free energy of coating films decreased with increasing the amount of MTMS. Surface roughness of coating films decreased with increasing the amount of MTMS when the reaction time was 6 h. When the reaction time was 24, 48 and 72 h, surface roughness of coating films decreased with increasing the amount of MTMS in the beginning, and then increased when further amount of MTMS was added. Plastic hardness increased with increasing the amount of MTMS. Elastic portion inversely decreased with increasing the amount of MTMS. Coating films were stable until 550°C. Thermal degradation temperature of coating films decreased with increasing the amount of MTMS.