Robust Giant Tetragonal Distortion Coupled with High-Spin Co3+ in Electron-Doped BiCoO3
| Autor: | Shogo Kawaguchi, Takafumi Yamamoto, Takumi Nishikubo, Shin-ya Koshihara, Yoichi Okimoto, Hajime Yamamoto, Yuki Sakai, Keisuke Yokoyama, Hayato Ishizaki, Masaki Azuma |
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| Rok vydání: | 2019 |
| Předmět: |
Spin states
010405 organic chemistry Chemistry Annealing (metallurgy) Oxide 010402 general chemistry 01 natural sciences 0104 chemical sciences Inorganic Chemistry Crystallography Tetragonal crystal system chemistry.chemical_compound Negative thermal expansion Metastability Orthorhombic crystal system Physical and Theoretical Chemistry Ambient pressure |
| Zdroj: | Inorganic Chemistry. 58:16059-16064 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/acs.inorgchem.9b02381 |
| Popis: | BiCoO3 is a PbTiO3 type of perovskite oxide with a giant tetragonal distortion (c/a = 1.27) that shows a pressure-induced transition from tetragonal to orthorhombic phases accompanied by a large volume shrinkage at 3 GPa. In this study, we carried out electron doping of BiCoO3 by substituting Ti4+ for Co3+ in order to destabilize the tetragonal phase and observe a giant negative thermal expansion (NTE) at ambient pressure. BiCo1-xTixO3 (x = 0, 0.1, 0.2, and 0.25) was successfully obtained by using high-pressure synthesis. However, the c/a ratio of the tetragonal phase was almost constant against x (≤0.2), and NTE was not observed at any x, suggesting that the tetragonal distortion coupled with high-spin Co3+ is robust against electron doping. In x = 0.25, a metastable orthorhombic phase was obtained by the high-pressure synthetic process, while it partially transformed into a tetragonal phase after annealing at 600 K. The stability of the giant tetragonal phase is strongly connected with the spin state of Co3+. |
| Databáze: | OpenAIRE |
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