Metal atom incorporation studies on AxMo6S8 Chevrel phases |
| |
Authors: | A.M. Umarji G.V.Subba Rao M.P. Janawadkar T.S. Radhakrishnan |
| |
Affiliation: | Materials Science Research Centre, Indian Institute of Technology, Madras 600 036, India;Materials Science Laboratory, Reactor Research Centre, Kalkpakkam 603 102, India |
| |
Abstract: | Group IIIa metals and Nb, Hg and Pb containing AxMo6S8 Chevrel phases have been synthesized by low temperature reaction (420–430°C) frorn A metal and Mo6S8. Some of these phases are hitherto unknown. Electrolysis method of preparation of AxMo6S8 reported by Schöllhorn does not yield the desired phases when A = Pb or Ag. Stoichiometry, thermal stability, electrical and superconducting properties of the compounds have been examined. In the PbxMo6S8 system, a series of phases with varying x have been prepared and studied. Group IIIa metal and Nb-compounds are found to be semiconductors with low energies of activation exhibiting p-type behavior in the range 77–300 K. Hg-phase behaves as a metal or a degenerate semiconductor and does not become superconducting above 4.2 K. X-Ray, resistivity and Tc studies show that for x ? 0.8 in PbxMo6S8, the compounds behave more like Mo6S8 and only for x ? 1.0 or (PbBi)1.0, the inherent behavior of the ternary Chevrel phase is exhibited. Seebeck coefficients are small and positive for Mo6S8, Cu and Pb-containing phases in the range 77–300 K. The results are discussed in the light of available band structure of these materials. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|