【摘要】 本文系统地研究了LaNi₃-H₂体系的吸放氢特性,并通过X射线衍射相分析及差热分析对LaNi₃在加热脱氢过程中发生的相变及相分解机理进行了研究。LaNi₃在室温下氢化后变成微晶氢化物,该氢化物在350℃以上放氢时则分解成LaNi₅和LaH₃,其相分解模型为:在分解过程形成中间相LaNi₂。该中间相随反复的加热而消失。氢致分解的最终结果是:LaNi₃-H₂体系的特性归结为LaNi₅-H₂体系的特性;P-C等温线随加热由两个平台变成一个平台。 从晶体结构和化合物的热力学稳定性等方面对LaNi₃的氢致分解机理进行了讨论,同时对P-C等温线出现的两个平台以及第二个平台消失的原因进行了分析。更多还原

【Abstract】 The phase transformation of LaNi₃, which is induced by dehydriding at high temperature was investigated by X-ray diffraction, differential thermal analysis（DTA）, etc. It was concluded that LaNi₃ is transformed from crystallinc state into microcrystalline hydride when activated at room temperature. The microcrystalline hydride is decomposed when dehydridcd above 350℃ and results in the formation of LaNi₅ and LaH₃ as follows:An interphase, LaNi₂, is formed during decomposition, and disappear after repeatedly dehydrided at high temperature. As the final result of dehydriding decomposition of LaNi₃-H₂, the P-C-T isotherms of LaNi₅-H₂ system are recognized. The P-C-T isotherms are gradually changed from two plateau to one plateau after heating repeatedly.The mechanism of the phase decomposition was discussed on the basis of crystal structure and thermodynamic stability of the compounds displayed during decomposition. Explanation for the shape of P-C-T isotherms was also given.更多还原