Pressure-induced collapse of the guest EU off-centering in type-I clathrate EU8Ga16Ge30

Ishimatsu, N. ; Yokoyama, K. ; Onimaru, T. ; Takabatake, T. ; Suekuni, K. ; Kawamura, N. ; Tsutsui, S. ; Mizumaki, M. ; Ina, T. ; Watanuki, T. ; Cuartero, V. ; Mathon, O. ; Pascarelli, S. ; Nishibori, E. ; Irifune, T.

Resumen: We have revealed the pressure-induced collapse of the guest Eu off-centering in type-I clathrate Eu8Ga16Ge30 by the measurements of extended X-ray absorption fine structure (EXAFS) at the Ge K-edge in a temperature range of 10–300 K. Our analysis of the EXAFS spectra at ambient pressure confirmed that the guest Eu is located in the off-centered positions at ¿offset = 0.39(1) Å away from the center of the Ga=Ge tetradodecahedron cage (14-cage). However, with applying pressure to 13.1 GPa, ¿offset decreases to zero, and the atomic density of Eu is concentrated near the center of the 14-cage with a broad distribution. The present result demonstrates a close relationship between ¿offset and the size of the cage: ¿offset decreases when the 14-cage shrinks by applying pressure. With further compression, we have observed a drastic change in the EXAFS spectra due to amorphization. In the amorphous phase, the first nearest neighbor Ge–Ga=Ge bond is longer than in the crystal phase, whereas the guest Eu atom is located randomly with respect to the Ge atoms.

Idioma: Inglés

DOI: 10.7566/JPSJ.88.114601

Año: 2019

Publicado en: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 88, 11 (2019), 114601 [9 pp]
ISSN: 0031-9015

Factor impacto JCR: 1.579 (2019)

Categ. JCR: PHYSICS, MULTIDISCIPLINARY rank: 46 / 84 = 0.548 (2019) - Q3 - T2

Factor impacto SCIMAGO: 0.77 - Physics and Astronomy (miscellaneous) (Q2)

Tipo y forma: Artículo (Versión definitiva)