形态对钯-氢体系热力学性质的影响

基于实验测定海绵Pd颗粒在278K-323K范围内吸放H2，D2的P-C-T曲线．结合文献给出的其它形态的Pd吸放氢结果进行系统比较分析．探讨了形态对钯-氢体系热力学性质的宏观影响和微观本质。在室温附近，氢的饱和固溶度与坪压随Pd的粒度减小而增加；Pd的形态或粒度对氢的饱和固溶度和吸氧坪压的影响程度刚随温度升高而减小，而且坪压之间的差别在温度较高时不再明显甚至消失。吸氘坪压差别大，解吸坪压差别小。Pd—H体系中α→β的相变热焓、热熵（绝计值)随粒度减小而减小，单晶Pd相应热力学函数最小。海绵Pd颗粒中的压力迟滞效应最明显．材料本底缺陷密度决定不同形态Pd-H体系的压力迟滞效应的大小。

Effect of Morphology on Thermodynamic Properties in Pd-H System

The pressure-composition (P-C) behavior of protium and deuterium in sponge Pd particle has been measured over a temperature range from 278 K to 323 K. Based on these data and combined with literature data, the effect of Pd crystal type and particle sizes on the thermodynamic properties in the Pd-H system was compared each other and discussed. The saturation solubility of hydrogen in solid solution region and the plateau pressure increase with decreasing Pd particle sizes at the ambient temperature. The effect of Pd morphology on above two parameters gets weaker at higher temperature and the difference of plateau pressure among several different Pd morphologies disappears. The absolute value of phase transformation enthalpy and entropy from solid solution to hydride decrease with decreasing particle sizes of Pd, but which are the smallest in single crystal Pd. The degree of hysteresis effect in Pd-H system depends on the background density in the sample, so it is the strongest in sponge Pd particle.