STUDIES ON LAYER DISORDER, MICROSTRUCTURAL PARAMETERS AND OTHER PROPERTIES OF TANTALUM SUBSTITUTED TUNGSTEN-MOLYBDENUM SELENIDE, W0.65MO0.35-XTAXSE2 ESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-0.35)

The present work deals with preparation and studies on structure deter mination, layer disorder, microstructural parameter and a few other pr operties of tantalum substituted W0.65Mo0.35-xTaxSe2, viz. W0.65Mo0.35 -xTaxSe2 (0 less than or equal to x less than or equal to 0.35). X-ray analysis shows that all these compounds possess MoS2 type structure. The particle size, r.m.s. strain, dislocation density, variability of interlayer spacing and fraction of planes affected by such defects hav e also been calculated for all compounds. It has been observed that W0 .65Mo0.20Ta0.15Se2 compounds possess small size and high values for ot her parameters. Room temperature magnetic susceptibility, thermoelectr ic power experiments and two probe electrical conductivity measurement s confirmed that all these compounds are diamagnetic p-type metals exc ept the parent compound W0.65Mo0.35Se2, which is a p-type semiconducto r. Thermal stability behavior of these compounds in air atmosphere has also been studied and based on weight loss in TG and X-ray data of th e oxidized products, formation of the respective oxidized products has been proposed. Scanning electron microscopy studies of these compound s have also been made.