Anisotropic Lattice Compression and Possible Valence Change in Kondo Compound CeAu2Si2

Lattice constants and crystal structure of tetragonal Kondo compound CeAu2Si2 have been investigated at high pressure in order to examine pressure-induced change of crystal structure and gradual valence change of Ce atom. It is found that the lattice constants a and c decrease with increasing pressure without any discontinuity up to 13 GPa at room temperature. The bulk modulus B0 and its pressure derivative B0' were obtained to be 112 GPa and 3.2. These values are comparable with other Kondo compounds. From the ρ(T) curve at high pressure which does not change so much under high pressure, it is suggested that the valence of Ce changes sluggishly with pressure and the Kondo state of CeAu2Si2 is very stable at high pressure.