Thermodynamics of the rhombohedral-cubic phase transition of ROF with R Y, La, Pr, Nd, SmEr
Thermodynamics of the rhombohedral-cubic phase transition of ROF with R Y, La, Pr, Nd, SmEr
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R Y、La、Pr、Nd、SmEr ROF 菱面体-立方相变的热力学
DOI：
10.1016/0925-8388(93)90466-z
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发表时间：
1993
影响因子：
6.2
通讯作者：
B. Hormann
中科院分区：
文献类型：
--
作者：
T. Petzel;V. Marx;B. Hormann
用差示扫描量热法测定了含有RY， La, Pr, Nd， SmEr的化学计量ROF的菱形-立方相变的温度和焓。相变温度范围为742 ~ 880 K，与文献数据吻合较好。随着阳离子半径的减小，LaOF、PrOF、NdOF和EuOF的跃迁焓和熵分别从5135±193 ~ 5504±169 J mol−1和6.60±0.25 ~ 6.908±0.21 J mol−1K−1增加，GdOF、tof、DyOF、HoOF、YOF和ErOF的跃迁焓和熵分别从7085±190 ~ 7903±187 J mol−1和8.02±0.24 ~ 9.04±0.27 J mol−1K−1增加。初步探讨了萤石型α-ROF的跃迁机理及跃迁熵大小与缺陷结构的关系。
The temperatures and enthalpies of the rhombohedral-cubic phase transition of stoichiometric ROF with R Y, La, Pr, Nd, SmEr, have been determined by differential scanning calorimetry. The temperatures of transition are found in the range 742–880 K in satisfactory agreement with literature data. The enthalpies and entropies of transition of LaOF, PrOF, NdOF and EuOF increase with decreasing cationic radius from 5135 ± 193 to 5504 ± 169 J mol−1and from 6.60 ± 0.25 to 6.908 ± 0.21 J mol−1K−1respectively, and for GdOF, TbOF, DyOF, HoOF, YOF and ErOF from 7085 ± 190 to 7903 ± 187 J mol−1and from 8.02 ± 0.24 to 9.04 ± 0.27 J mol−1K−1. The transition mechanism and relations between the magnitude of the entropy of transition and the defect structure of fluorite-type α-ROF are tentatively discussed.