VQ_2(Q=H,D,T)热力学氢同位素效应的理论研究

稀有金属材料与工程, 2010, 39(2): 204-208.

VQ_2(Q=H,D,T)热力学氢同位素效应的理论研究

雷强华 ^1, , 陈长安 ^2, , 黄理 ^3, , 张永彬 ^4,

1.表面物理与化学国家重点实验室,四川,绵阳,621907

2.中国工程物理研究院,四川,绵阳,621900

3.中国工程物理研究院,四川,绵阳,621900

4.表面物理与化学国家重点实验室,四川,绵阳,621907

基金项目: Science Foundation of China Academy of Engineering Physics(Y10-2) 国家自然科学基金(20971114)

关键词：钒 , 氢 , 同位素效应 , 热力学

Theoretical Study on Thermodynamic Hydrogen Isotope Effect of VQ_2 (Q=H, D and T)

Lei Qianghua ^1, , Chen Chang'an ^2, , Huang Li ^3, , Zhang Yongbin ^4,

1.表面物理与化学国家重点实验室,四川,绵阳,621907

2.中国工程物理研究院,四川,绵阳,621900

3.中国工程物理研究院,四川,绵阳,621900

4.表面物理与化学国家重点实验室,四川,绵阳,621907

Keywords： vanadium , hydrogen , isotope effect , thermodynamics

基于量子力学第一性原理,采用赝势平面波函数与密度泛函结合的方法,计算并研究V、VH_2、VD_2、VT_2体系的晶格动力学特征及热力学函数,采用热力学方法分析钒吸氢生成VQ_2(Q=H,D,T)的热力学同位素效应.晶格动力学性质研究表明,VQ_2的热力学同位素效应主要是氢同位素在钒晶格中的振动频率不同导致的.VQ_2生成反应在10~1000 K的温度范围内标准吉布斯自由能变由-50 kJ·mol~(-1)近似线性上升至140 kJ·mol~(-1).平衡压力与温度关系表明,在高于常温的条件下,平衡压力随温度急剧升高;钒吸附氢同位素生成二氢化钒在整个温度范围内均表现为负同位素效应.

Based on ab-initio principle and pseudo-potential plain wave function combined with density function theory, crystal lattice dynamical characteristics and thermodynamical functions of V, VH_2, VD_2 and VT_2 were calculated. The thermodynamical isotope effect was analyzed based on those calculated data. Calculation results show that both difference of vibration frequency of atoms in VQ_2 (Q=H, D and T) and difference of oscillation frequency of hydrogen isotopes are mainly responsible for the hydrogen isotope effect. The standard Gibbs free energy change of the absorption reaction rises from -50 kJ/mol to 140 kJ/mol with the temperature increasing from 10 K to 1000 K. The equilibrium pressure climbs drastically when temperature is higher than room temperature. Within the whole temperature range, only inverse hydrogen isotope effect is found

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