【摘要】 本文用X射线多晶衍射方法和差热分析方法研究了LaNi_5-xSi_x（x≤1.25）的相关系,用排水取气法测量了样品的吸H₂性能,LaNi₅,的固溶体和新的三元化合物LaNi₄Si形成共晶体系,共晶温度1170℃,共晶点x=0.96,在单相区中LaNi₅,相点阵常数随Si替代量增加,a减小,c增大,三元化合物LaNi₄Si属正交晶系,点阵常数a=8.382,b=5.210,c=3.989。测量密度D₀=7.59g/cm³,每单胞含两个化合式单位,可能的空间群为D_2h⁵,C₍2v_<sup>2和C_2v⁴,它具有可逆的吸放H₂性能,吸H₂后形成氢化物LaNi₄SiH₃.6。La_l-ySi_yNi,系列样品吸H₂量随Si含量增加而很快下降,LaNi_5-xSi_x系列样品吸H₂量随Si含量的增加稍略下降,平台压力也下降,LaNi_4.8Si_0.2的生成自由能为476cal/mol H₂,固溶体氢化物的稳定性比LaNi₁高。更多还原

【Abstract】 In this work, the phase relations of LaNi5-xSix(x≤1.25) have been studied by means of X-ray powder diffraction method and DTA method, and the hydrogen absorption properties of the samples have been measured using gas-gathering method. Theα-phase (LaNi5) and the new discovered ternary compound LaNi4Si (β) forms a eutectic system. The eutectic reactionis α+β 1170℃/ L. The eutectic point is at x=0.96. In the single phase area of a-phase, the lattice parameter a de-creases and c increases with the substitution of Si, The ternary compound LaNi4Si belongs to orthorhqmbic system with lattice parameters a = 8.382 A, b = 5.210 A, c = 3.989A. The measured density is 7.59 g/cm3. There are two formula unit per unit cell. Possible space groups are D2h5,C2v2,C2v4. The hydrogen quantities absorbed by the La1-ySiyNi5 samples decrease rapidly with Si content increasing. The absorbed hydrogen quantities of La-Ni5-xSix samples vary slowly with the Si content and the plateau pressures decrease. The formation free energy of LaNi4.8 Si0.2 H6.5 is 475 cal/mol H2. Si substitution increased the stability of hydrides. The new compound LaNi4Si has reversible hydrogen absorption and desorption properties with formation of hydride LaNi4SiH3.6.更多还原