Phase transitions in quasi-one-dimensional selenide BaNbSe{sub 3} and superconductivity in BaNb{sub 2}Se{sub 5}

Journal Article · Fri Aug 01 04:00:00 EDT 1997 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1997.7443· OSTI ID:568118

Ohtani, T; Honji, S ^[1]; Takano, M ^[2]

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1. Okayama Univ. of Science, Okayama (Japan)
2. 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, Journal Name: Journal of Solid State Chemistry Journal Issue: 1 Vol. 132; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM COMPOUNDS
NIOBIUM SELENIDES
PHASE TRANSFORMATIONS
SEEBECK EFFECT
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE