期刊
APPLIED PHYSICS LETTERS
卷 94, 期 19, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3136764
关键词
band structure; crystal structure; iron compounds; lattice constants; oxidation; Seebeck effect; space groups; specific heat; superconducting transition temperature; terbium compounds; type II superconductors; XANES; X-ray diffraction
资金
- National Science Council of Taiwan [NSC 97-2628-M-259-001-MY3, NSC 97-2113-M-002-012-MY3]
- Australian Research Council [DP0558753]
- Japan Science and Technology Agency (JST)
- TRIP of Japan
- Korea Science and Engineering Foundation of the Ministry of Science and Technology (MOST/KOSEF) of Kore
The crystal structure and the electronic and thermal properties of a high-quality polycrystalline TbFeAsO0.85 sample made by a high-pressure technique are investigated. The crystal structure, as determined by synchrotron X-ray powder diffraction, possesses a tetragonal unit cell (space group: P4/nmm) with lattice parameters of a=b=3.8851 A and c=8.3630 A. In order to elucidate the electronic structure and oxidation states of corresponding elements, X-ray absorption near-edge structure (XANES) spectra are presented. The XANES spectra confirm that the oxidation states of Fe, As, and Tb in the TbFeAsO0.85 sample are similar to Fe2+, similar to As3-, and similar to Tb3+, respectively, which are consistent with the previously reported band structure calculations. The n-type character of the charge carriers as revealed from XANES spectra is corroborated by the negative sign of the Seebeck coefficient (S) in the present study. The heat capacity (C-P) measurement shows an anomaly in the vicinity of the superconducting transition temperature (T-c=42.5 K), which confirms the bulk nature of the superconductivity in this material.
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