The hydrogen-absorbing intermetallic compound LaNi5 was activated using volumetric apparatus (a HTP1-V volumetric hydrogen storage analyser) at 333 K. Pressure-composition isotherms (PCIs) were measured through the first 8 hydrogenation cycles and show considerable change in the hydrogen absorption behaviour through the activation process. A series of isotherms at temperatures in the range 308 413 K were also measured. The higher temperature measurements show a clear indication of the formation of an intermediate  phase between the solid solution  phase and  hydride phase. Van t Hoff plots were determined from the measured isotherms and the average value for H of 15.6 kJ/mol ½H2 was found to be in good agreement with the literature. 動態(tài)氣體吸附儀/動態(tài)氣體吸附分析儀