X-ray Study with Synchrotron Radiation for Filled Skutterudite CeRu4As12at Ambient Pressure and at High Pressures

Abstract

Powder x-ray diffraction patterns of CeRu 4 As 12 with synchrotron radiation have been studied at ambient pressure and at high pressures. A crystal structure of CeRu 4 As 12 was refined by the Rietveld analysis of the powder x-ray diffraction data at ambient pressure. The thermal equivalent isotropic parameter ( B eq ) of Ce in CeRu 4 As 12 is 1.30 A 2 , considerably large. The large value of B eq may closely be related to the rattling effect. The volume vs. pressure curve for this arsenide has in detail been investigated at room temperature. The cell volume of CeRu 4 As 12 decreased smoothly with increasing pressure up to 10 GPa. A bulk modulus was estimated from the volume vs. pressure curve fitted by a Birch equation of state. The bulk modulus ( B 0 ) and its pressure derivative ( B 0 ') of CeRu 4 As 12 are 127 ±3 GPa and 5.5 ±9, respectively. The value of B 0 for this arsenide is smaller than that of CeRu 4 P 12 , larger than that of CeRu 4 Sb 12 . The bulk moduli of CeRu 4 X 12 (X = P, As and Sb) dec...