Thermodynamic particularities of some CeNi5-based metal hydride systems with high dissociation pressure
Thermodynamic particularities of some CeNi5-based metal hydride systems with high dissociation pressure
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DOI：
10.1016/0925-8388(95)01869-7
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发表时间：
1995-12
影响因子：
6.2
通讯作者：
S. Klyamkin;V. Verbetsky;A. A. Karih-A.
中科院分区：
文献类型：
--
作者：
S. Klyamkin;V. Verbetsky;A. A. Karih-A.
用高压技术研究了CeNi5H2、Ce0.8La0.2Ni5H2和Ce0.8La0.2Ni4.7Cu0.3-H2体系在几个活化吸附-脱附循环中的热力学行为。测定了273~353K温度范围内的P-C等温线，计算了氢化物生成和分解反应的热力学参数。对于所有被研究的体系，都获得了相同的氢容量(在1000atm和296K下，单位AB5的氢原子为6.5-6.8H原子)和相同的等温线形状，具有较长的近水平平台和很大的滞后。在CeNi5-→-Ce0.8La0.2Ni5-→-Ce0.8La0.2Ni4.7Cu0.3范围内，合金成分的变化导致了平台长度的增加和滞后系数的降低。在两个或三个活化周期后，磁滞系数也显著降低，比第一个周期降低了4-8倍。这一现象不仅与吸附压力的降低有关，还与解吸压力的显着增加有关。活化过程中P1Pactin平衡压力的相对变化不依赖于吸附反应的合金成分，但在脱附过程中，随着La和Cu部分替代Ce和Ni，P1Pactin平衡压力相应减小。
The thermodynamic behaviour of the CeNi5H2, Ce0.8La0.2Ni5H2and Ce0.8La0.2Ni4.7Cu0.3-H2systems during a few activation absorption-desorption cycles was studied by means of high gaseous pressure technique. P-C isotherms in the temperature range from 273 to 353 K were measured and thermodynamic parameters for hydride formation and decomposition reactions were calculated. For all studied systems the same hydrogen capacity (6.5–6.8 H atoms per AB5unit at 1000 atm and 296 K) and the same isotherm shape with a long nearly horizontal plateau and very large hysteresis were obtained. The change in alloy composition in the range CeNi5→ Ce0.8La0.2Ni5→ Ce0.8La0.2Ni4.7Cu0.3led to an increase in plateau length and a decrease in hysteresis factor PabsPdes. The hysteresis factor also decreased considerably after two or three activation cycles, by 4–8 times as compared with the first cycle. This phenomenon was connected not only with an absorption pressure decrease but also with a significant increase in desorption pressure. The relative change P1Pactin equilibrium pressure during the activation did not depend on alloy composition for the absorption reaction, but in the case of desorption it decreased with partial substitution of Ce and Ni by La and Cu correspondingly.