Open AccessTHE INFLUENCE OF Si ON PHASE RELATION AND HYDROGEN ABSORPTION PROPERTIES OF LaNi5
Author(s) -
Jingkui Liang,
Zhao Jing-Tai
Publication year - 1986
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.35.505
Subject(s) - eutectic system , materials science , hydrogen , hydride , ternary operation , lattice constant , desorption , analytical chemistry (journal) , absorption (acoustics) , solid solution , lattice (music) , hydrogen storage , ternary numeral system , phase (matter) , crystallography , diffraction , chemistry , alloy , metallurgy , adsorption , physics , organic chemistry , computer science , acoustics , optics , composite material , programming language
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. The α-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?, b = 5.210?, c = 3.989?. 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 LaNi4.8Si0.2H6.5 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.