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Rare Earth Dependence of Einstein Temperatures in Filled Skutterudite Compounds REFe 4 P 12 (RE = La, Ce, Pr, Nd, and Sm)

2011; Physical Society of Japan; Volume: 80; Issue: 7 Linguagem: Inglês

10.1143/jpsj.80.074603

1347-4073

Masaichiro Mizumaki, Satoshi Tsutsui, Tomoya Uruga, Hajime Tanida, Daisuke Kikuchi, Hitoshi Sugawara, Hideyuki Sato,

X-ray Diffraction in Crystallography

Extended x-ray absorption fine structure (EXAFS) measurements were carried out at the K -edge of rare-earth ions in REFe 4 P 12 (RE = La, Ce, Pr, Nd, and Sm) at various temperatures. Distance between a rare-earth atom and neighboring atoms in each REFe 4 P 12 compound was determined in this work. The obtained results agree reasonably with previous results of diffraction experiments. The temperature dependence of EXAFS amplitude was successfully analyzed using the Einstein model in each compound. The Einstein temperatures obtained by the analyses show a significant rare-earth dependence. Quantitative comparison between the present EXAFS measurements and phonon measurements such as inelastic x-ray/neutron scattering suggests that reduced mass treatment is essential for estimating Einstein temperatures. This indicates that finite binding energy exists between a rare-earth atom and P atoms at least in REFe 4 P 12 compounds.