Single-Crystal Electrical Resistivities of Some Ta-Rich Chalcogenides
β Scribed by Kyungsoo Ahn; Timothy Hughbanks
- Publisher
- Elsevier Science
- Year
- 1993
- Tongue
- English
- Weight
- 468 KB
- Volume
- 102
- Category
- Article
- ISSN
- 0022-4596
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β¦ Synopsis
Vapor phase transort synthesis of several Ta-rich chalcogenides affords us good single crystals for four-probe measurements of their electrical resistivities. A comparison of the temperature dependent resistivities of (\mathrm{Ta}{2} \mathrm{~S}) and (\mathrm{Ta}{3} \mathrm{~S}{2}) show that the latter compound is a considerably poorer conductor for all temperatures from (1510270 \mathrm{~K}), as predicted in our earlier band structure study of these materials and consistent with the recent work of Nozaki and coworkers. In both cases, resistivities were measured along the direction parallel to the ({ }{x}^{1}\left[\mathrm{Ta}{5} \mathrm{Ta}\right]) chains that serve as these materials' basic structural building blocks. The compounds (\mathrm{T}{\mathrm{a}{9}} M{2} \mathrm{~S}{\mathrm{f}}(M=\mathrm{Fe}, \mathrm{Co}, \mathrm{Ni})) show normal metallic behavior over the same range of temperatures. A distortion that leads to a doubling of the (c)-axis length for the (\mathrm{Fe}) and (\mathrm{Co}) containing compounds seems to have no significant effect on the electronic density of states at the Fermi level in either material. In contrast, the compounds (\mathrm{Ta}{11} M_{2} \mathrm{Se}{8}(M=\mathrm{Fe}, \mathrm{Co}, \mathrm{Ni})) exhibit markedly different resistivities as a function of temperature. While (\mathrm{Ta}{13} \mathrm{Fe}{2} \mathrm{Se}{8}) and (\mathrm{Ta}{11} \mathrm{Ni}{2} \mathrm{Se}{8}) behave much like the structurally similar (\mathrm{Ta}{9} M_{2} \mathrm{~S}{6}) compounds, the resistivity of (\mathrm{Ta}{11} \mathrm{Co}{2} \mathrm{Se}{8}) shows a curiously weak temperature dependence and a high residual value at the lowest temperatures of measurement ( (15 \mathrm{~K}) ). Powder diffraction data for this compound suggests that crystals prepared at low temperature have lower symmetry that the Pnnm space group originally reported. 01993 Acastemic Press. Inc.
π SIMILAR VOLUMES
This paper reports the results of a study of high purity chromium single crystal electric resistivity. The chromium single crystal used in this study was produced from commercially available 5N electrolytic chromium. The gaseous impurity level improved during single crystal production. The crystal s
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