Deductions about the structure of phase III from thermodynamic measurements on solid isotopic methanes
Deductions about the structure of phase III from thermodynamic measurements on solid isotopic methanes
复制标题
从固体同位素甲烷热力学测量中推论第三相结构
DOI：
10.1063/1.437472
复制
发表时间：
1979
期刊：
影响因子：
--
通讯作者：
J. A. Morrison
中科院分区：
文献类型：
--
作者：
M. White;J. A. Morrison
在固体甲烷同位素研究中，测定了CHD_3的热容，其范围为0.15<T<3K。在测量区域的肖特基异常中发现了一些结构，它与固体中核自旋对称物种的组成有关。没有自旋转换的证据。从热容和其他数据计算了CHD_3的熵随温度的变化，并利用它来推断固体中的量子无序。结合CH3D、CH2D2和CHD3的结果得出结论，固体甲烷的第III相的结构是量子无序的，并且它必须包含至少三种类型的亚晶格。一个由两个四面体分子场和一个对称性低于四面体分子场的子晶格组成的模型，满意地解释了实验观察。
In a continuing study of the solid isotopic methanes, the heat capacity of solid CHD3 has been measured in the range 0.15<T<3 K. Some structure is found in a Schottky anomaly in the region of the measurements and it is related to the composition of nuclear spin symmetry species in the solid. There is no evidence of spin conversion. The entropy of CHD3 has been calculated as a function of temperature from the heat capacity and other data, and is used to make deductions about quantum disorder in the solid. Combined results for CH3D, CH2D2 and CHD3 lead to the conclusion that the structure of phase III of solid methane is quantum disordered and that it must contain at least three types of sublattice. A model consisting of two sublattices with tetrahedral molecular fields and one with symmetry lower than tetrahedral, accounts for the experimental observations satisfactorily.