The Heat Capacity of Thorium Dioxide from 10 to 305°K. The Heat Capacity Anomalies in Uranium Dioxide and Neptunium Dioxide
The Heat Capacity of Thorium Dioxide from 10 to 305°K. The Heat Capacity Anomalies in Uranium Dioxide and Neptunium Dioxide
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二氧化钍从 10 到 305°K 的热容二氧化铀和二氧化镎的热容异常。
DOI：
10.1063/1.1698683
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发表时间：
1953
影响因子：
4.4
通讯作者：
E. Westrum
中科院分区：
文献类型：
--
作者：
D. W. Osborne;E. Westrum
用绝热量热计在10 ~ 305°K范围内测定了二氧化钍的热容。正如预期的那样，在热容中没有观察到异常。焓、熵和自由能是根据热容数据计算的，并在不同温度下制成表格。在298.16°K时，熵和焓分别为15.593±0.02 cal de−1 mol−1和2524.4±3 cal mol−1。假设二氧化铀和二氧化镎的晶格熵等于二氧化钍的晶格熵，则在298.16°K时，二氧化铀的磁熵贡献为3.0 cal deg−1 mol−1，二氧化镎的磁熵贡献为3.6 cal deg−1 mol−1。这些值略大于自旋值（二氧化铀的rln3 =2.18卡度−1摩尔−1，二氧化铀的rln4 =2.75卡度−1摩尔−1）。在298.16°K时，其他同形锕系二氧化物的熵估计为：PaO2为17.8，PuO2为19.7，AmO2为20.0，CmO2为20.3，…
The heat capacity of thorium dioxide was determined from 10 to 305°K in an adiabatic calorimeter. As expected, no anomaly was observed in the heat capacity. The enthalpy, entropy, and free energy were calculated from the heat‐capacity data and are tabulated for several temperatures. At 298.16°K the entropy and the enthalpy are, respectively, 15.593±0.02 cal deg−1 mole−1 and 2524.4±3 cal mole−1. By assuming the lattice entropy of uranium dioxide and of neptunium dioxide to be equal to the entropy of thorium dioxide, the magnetic entropy contributions at 298.16°K were evaluated as 3.0 cal deg−1 mole−1 for uranium dioxide and 3.6 cal deg−1 mole−1 for neptunium dioxide. These values are somewhat greater than the spinonly values (R ln 3=2.18 cal deg−1 mole−1 for uranium dioxide and R ln 4=2.75 cal deg−1 mole−1 for neptunium dioxide). The entropies of the other isomorphous actinide dioxides at 298.16°K are estimated to be (in cal deg−1 mole−1) 17.8 for PaO2, 19.7 for PuO2, 20.0 for AmO2, 20.3 for CmO2, 20.6 for...