ABSTRACT Enthalpy increments of the ternary compounds of rare earth uranium oxides, RE6UO12 (RE = La, Nd, Sm, Eu, Gd) were measured by inverse drop calorimetry in the temperature range 533-1738K. These compounds (RE6UO12) were prepared by gel combustion synthesis and characterized by XRD. From the measured enthalpy increment values, thermodynamic functions, viz. heat capacity, entropy, Gibb's energy functions were computed. The trend in variation of heat capacity was in the order: Eu6UO12>Sm6UO12>Nd6UO12>La6UO12>Gd6UO12. This trend is explained based on (i) phonon (ii) dilatational and (iii) Schottky contributions to the heat capacity. The trend in variation of heat capacity of RE6UO12 is similar to that of RE2O3. GRAPHICAL ABSTRACT

中文翻译：

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核工业中感兴趣的菱面体陶瓷 (RE6UO12) 的热表征

摘要 稀土铀氧化物三元化合物 RE6UO12（RE = La、Nd、Sm、Eu、Gd）的焓增量是通过逆滴量热法在 533-1738K 温度范围内测量的。这些化合物（RE6UO12）是通过凝胶燃烧合成制备的，并通过XRD表征。从测量的焓增量值，热力学函数，即。计算热容、熵、吉布氏能量函数。热容变化趋势为：Eu6UO12>Sm6UO12>Nd6UO12>La6UO12>Gd6UO12。这种趋势是基于 (i) 声子 (ii) 膨胀和 (iii) 肖特基对热容的贡献来解释的。RE6UO12 的热容变化趋势与 RE2O3 相似。图形概要