EXAFS Debye-Waller factors of La and Ni in LaNi5

XAFS measurements of the La L3 and Ni K-edges for LaNi5 were done at temperatures of 20, 100, 200 and 293 K. The temperature dependences of the Debye-Waller factors e−2σ2k2 for La and Ni are deduced. The results show that mean square fluctuation in interatomic distance σ2 of La for LaNi5 is fairly large and the Debye temperature ΘD of La changes with temperature. These results indicate that the La atom with large atomic size changes its atomic position easily in LaNi5. The large σ2 value of A (rare earth) elements for AB5 compounds might be correlated to their high capability of the hydrogen absorption and desorption.