Synthesis and thermoelectric power measurements of TlGaSe 2 single crystals
TlGaSe2single crystals were grown by modified Bridgman method. Thermoelectric power measurement were carried out in a brass working chamber designed for this purpose, allow measurements in a wide range of temperature under vacuum. The experimental results indicates that TlGaSe2 is of p-type conductivity. Throughout these measurements, various parameters such as effective mass of charge carriers, carrier mobility, diffusion coefficient, relaxation time and diffusion length for both majority and minority carriers were found. In addition to these pronounced parameters, the efficiency of the thermoelectric element (figure of merit) was evaluated, which leads to better application in many fields. [A. T. Nagat, S. A. Hussein, S. E. Al Garni. Synthesis and thermoelectric power measurements of TlGaSe2 single crystals. Life Sci J 2014;11(8):418-422]. (ISSN:1097-8135). http://www.lifesciencesite.com. 54
High-pressure Raman study of the ternary chalcogenides TlGaS2, TlGaSe2, TlInS2, and TlInSe2
The Raman spectra of tetragonal TlIn${\mathrm{Se}}_{2}$ and monoclinic TlGa${\mathrm{S}}_{2}$, TlGa${\mathrm{Se}}_{2}$, and TlIn${\mathrm{S}}_{2}$ have been investigated as a function of pressure at constant temperatures (300 and 110 K, TlIn${\mathrm{Se}}_{2}$ only at 110 K). Contrary to earlier assignment the structure of the monoclinic compounds can be described in the space group $\frac{C2}{c}$. The appearance and disappearance of Raman modes with increasing pressure are due to a crossing of bands with ${A}_{g}$ and ${B}_{g}$ symmetry and do not indicate the occurrence of a structural phase transition. In TlIn${\mathrm{S}}_{2}$ we observe modes with a negative pressure dependence indicating an impending phase transition at pressures above the maximum pressure of our measurements. The dependence of $(\frac{1}{\ensuremath{\nu}})(\frac{d\ensuremath{\nu}}{\mathrm{dp}})$ on $\ensuremath{\nu}$ of the observed Raman bands in these compounds reveals that a hierarchy of bonding forces is present.
Preparation of hydrophilic poly(vinyl butyral) hollow fiber membrane via thermally induced phase separation
Abstract Hydrophilic microporous hollow fiber membranes were prepared via thermally induced phase separation (TIPS). Poly(vinyl butyral) (PVB) and three kinds of polyethylene glycols (PEG) with the molecular weight of 200, 400 and 600 were used as polymer and diluents. In all cases, liquid–liquid (L–L) phase separation occurred and asymmetric cellular structures with the smaller pores at the outer surface were obtained. The properties of membranes such as pore size, water permeability, solute rejection and intensity were investigated by changing molecular weight of PEG, concentration of PVB, composition of the bath and air gap distance. The smaller molecular weight of PEG, the more PEG in the bath and the shorter air gap distance resulted in the higher water permeability, the lower solute rejection property and the lower mechanical strength.