Evolution of Negative Thermal Expansion and Phase Transitions in Sc1-xTixF3

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• 作者：Cody R. Morelock ; Leighanne C. Gallington ; Angus P. Wilkinson
• 刊名：Chemistry of Materials
• 出版年：2014
• 出版时间：March 11, 2014
• 年：2014
• 卷：26
• 期：5
• 页码：1936-1940
• 全文大小：411K
• 年卷期：v.26,no.5(March 11, 2014)
• ISSN：1520-5002

文摘

The cubic ReO₃-type material ScF₃ exhibits strong isotropic negative thermal expansion (NTE) over a wide temperature range while remaining cubic. Control of its thermal expansion was investigated by forming Sc_1-xTi_xF₃ solid solutions, which were characterized by synchrotron powder diffraction at ambient pressure from 100 to 500 K. TiF₃ is fully soluble in ScF₃ at a synthesis temperature of 1338 K. The temperature for the cubic-to-rhombohedral phase transition in Sc_1-xTi_xF₃ varies linearly with composition (above 100 K), and, at large x, the transition is clearly first-order. The rhombohedral phase for each composition examined exhibits strongly positive thermal expansion, while the expansion of the cubic phase (between 420 and 500 K) is negative for all Sc_1-xTi_xF₃.