PREPARATION AND PROPERTIES OF THERMOELECTRIC MATERIALS
COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL PARIS (FRANCE)
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Molybdenum telluride, MoTe2, was prepared by chemical transport reaction. Pure Mo and Te are placed in a horizontal quartz tube at about 800 C. Deposition is accomplished at about 750 C wtih Br as the transport agent. The temperature gradient is important, small variations in temperature stopping the transport phenomenon and sometimes causing wide and thin crystals, 1 to 2 sq cm inAREA, TO GRO ON THE Mo the crystals are probably Mo2Te3. The specific gravity of MoTe2 is 8.5 the crystals are soft and make black marks on paper. Standard X-ray analysis on single crystals of MoTe2 was performed with the rotating crystal method Cu K-alpha radiation. The first lattice constant of the hexagonal system was expressed by the equation a equals 3.52 or - 0.05 angstrom units. With the axis of rotation parallel to the c axis, c equals 14 or - 0.2 angstroms. The following compounds are also being prepared MoSe2, WSe2, and WTe2.