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研究了Sn替代贮氢合金LaNi5 和MlNi5(Ml=富镧混合稀土 )中部分Ni对合金的结构、吸氢容量和平衡氢压等性能的影响。用X射线衍射进行物相分析 ,测试了 2 98K ,31 3K ,333K温度下合金的吸、放氢 p—c—T曲线。结果表明 ,MlNi5 xSnx 合金 (x =0 ,0 .1 )为六方晶体结构的单相组织。以Sn部分取代Ni,使平台压力降低 ,吸、放氢滞后减小 ,而吸氢能力降低很小。利用电负性、电子浓度及原子尺寸等参数的半经验模型 ,计算的ΔH 与实验值符合较好 ,因此 ,少量Sn替代Ni时 ,影响合金热力学性质的主要因素是外层电子数的变化。
The effects of partial substitution of Sn for hydrogen substitution on the structure, hydrogen storage capacity and equilibrium hydrogen pressure of hydrogen storage alloys LaNi5 and MlNi5 (Ml = lanthanum mixed rare earth) were investigated. Phase analysis was carried out by X-ray diffraction. The p-c-T curve of the as-received and desorbed alloys was tested at 2 98K, 31 3K and 333K. The results show that the MlNi5 xSnx alloy (x = 0, 0. 1) is a hexagonal single phase structure. Partial replacement of Ni with Sn reduced the pressure in the platform, reduced the hydrogen absorption and hydrogen release, and decreased the hydrogen absorption capacity. Using the semi-empirical model of electronegativity, electron concentration and atomic size, the calculated ΔH is in good agreement with the experimental data. Therefore, when a small amount of Sn replaces Ni, the main factor affecting the thermodynamic properties of the alloy is the change of the number of electrons in the outer layer.