On the theory of hydrogen orderings in tantalum hydrides
On the theory of hydrogen orderings in tantalum hydrides
复制标题
氢化钽中的氢有序理论
DOI：
10.1088/0953-8984/3/25/003
复制
发表时间：
1991
期刊：
影响因子：
--
通讯作者：
V. Zinenko
中科院分区：
文献类型：
--
作者：
V. Vaks;V. Zinenko
本文采用先前开发的用于描述nbhx型体系中氢的统计性质的模型和方法来研究tax中α、α′、β、δ和in相之间的转变。如果假设TaHx中氢偏焓hH(x)的浓度依赖性在xc附近有一个近似于0.5的异常，就可以很自然地解释所观察到的相图（x， T）的主要特征。然后，将有序相的平均场常数值作为模型的参数，可以很好地描述整个（x， T）范围内taxx复相图的所有主要特征。作者还讨论了有序相的结构和有序参数的温度依赖性。在无序α相的中子或x射线衍射实验中，预测了某些临界浓度波的反常软化现象。
The model and methods developed earlier for describing the statistical properties of hydrogen in the NbHx-type systems are used to investigate the transition between the phases alpha , alpha ', beta , delta and in in TaHx. The main features of the observed phase diagram (x, T) can be naturally explained if one assumes that the concentration dependence of the hydrogen partial enthalpy hH(x) in TaHx has an anomaly near xc approximately=0.5 similar to that established earlier for NbHx. Then, treating values of the mean-field constants in the ordered phases as parameters of the model one can fairly well describe all the main features of the complex phase diagram of TaHx in the whole (x, T) range considered. The authors also discuss the structure of the ordered phases and the temperature dependences of the order parameters. An anomalous softening for some critical concentration waves is predicted which can be observed in neutron or X-ray diffraction experiments for the disordered alpha -phase.