Evidence for multiple phase transitions in La1-xCaxCoO3

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:310

Article; Proceedings Paper

Kriener, M. ; Braden, M. ; Senff, D. ; Zabara, O. ; Lorenz, T.

关键词: specific heat;    thermal expansion;    spin-state transition;    metal-insulator transition;    double-exchange mechanism;   

DOI  :  10.1016/j.jmmm.2006.10.529

来源: Elsevier

【 摘 要 】

We report thermal-expansion and specific-heat data of the series La1-xCaxCoO3 for 0 <= x <= 0.3. For x = 0 the thermal-expansion coefficient alpha(T) features a pronounced maximum around T = 50 K caused by a temperature-dependent spin- state transition from a low-spin state (S = 0) at low temperatures towards a higher spin state of the Co3+ ions. The partial substitution of the La3+ ions by divalent Ca2+ ions causes drastic changes in the macroscopic properties of LaCoO3. Around x approximate to 0.125 the large maximum in alpha(T) has completely vanished. With further increasing x three different anomalies develop. (c) 2006 Elsevier B.V. All rights reserved.

【 授权许可】

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