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Metal oxides showing negative thermal expansion by heating
Temperature-induced A-B Intersite Charge Transfer in an A-site-ordered LaCu3Fe4O12 Perovskite
| We have found that the transition-metal oxide, LaCu3Fe4O12, having an A-site-ordered perovskite structure, which are prepared by heating the metal oxides of Fe, Cu and lanthanum (La) under 100,000 atm at 1100?C, shows a large negative thermal expansion at about 120?C (approximately 1% isotropical contraction in volume). The physical properties of the material are also considerably changed at the transition temperature: paramagnetism-to-antiferromagnetism and metal-to-insulator isostructural phase transitions are observed. We have confirmed that the changes in above structural and physical properties originate from the intersite charge transfer between the A-site Cu and B-site Fe ions. |
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