We present a model for the determination of the thermal equilibrium concentrations of Bjerrum defects, molecular point defects, and their aggregates in ice I-h. First, using a procedure which minimizes the free energy of an ice crystal with respect to the numbers of defect species, we derive a set of equations for the equilibrium concentrations of free Bjerrum and point defects, as well their complexes. Using density-functional-theory calculations, we then evaluate the binding energies of Bjerrum-defect/vacancy and Bjerrum-defect/interstitial complexes. In contrast to the complexes which involve the molecular vacancy, the results suggest that the molecular interstitial binds preferentially to the D-type Bjerrum defect. Using both theoretical binding and formation free energies as well as the available experimental data, we find that the preferential binding and the substantial presence of the interstitial as the predominant point defect in ice I-h may lead to conditions in which the number of free D defects becomes considerably smaller than that of free L defects. Such a scenario could possibly be involved in the experimentally observed inactivity of D-type Bjerrum defects in the electrical properties of ice I-h. (c) 2008 American Institute of Physics.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据