Phase transitions in quasi-one-dimensional selenide BaNbSe{sub 3} and superconductivity in BaNb{sub 2}Se{sub 5}
- Okayama Univ. of Science, Okayama (Japan)
- Kyoto Univ. (Japan)
Samples with various compositions around BaNbSe{sub 3} were prepared. X-ray analysis revealed that the compound is stable at the composition of BaNb{sub 0.80}Se{sub 3}, which formally requires Nb{sup 5+} ions (d{sup 0}). The single-phase region extends to the composition BaNb{sub 0.95}Se{sub 3}. A semiconductor-to-metal transition was observed at {approximately}140 K in BaNb{sub 0.95}Se{sub 3}. Seebeck measurements showed that the dominant carriers were electrons, which are considered to originate from Nb{sup 4+} ions d{sup 1} coexisting with Nb{sup 5+} ions. On the basis of detailed phase study, the transition was revealed to be intrinsic to BaNb{sub 0.95}Se{sub 3} with a slight Ba excess shows a semiconductor-to-semiconductor transition at 200-300 K. Seebeck measurements showed that the dominant carriers are electrons above the transition and are holes below the transition. A new compound, BaNb{sub 2}Se{sub 5} with a BaTa{sub 2}S{sub 5}-type structure, was found to show superconductivity at 2.5 K.
- OSTI ID:
- 568118
- Journal Information:
- Journal of Solid State Chemistry, Vol. 132, Issue 1; Other Information: PBD: Aug 1997
- Country of Publication:
- United States
- Language:
- English
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