Anisotropic lattice compression of α- and β-CePdZn

The lattice constants of ZrNiAl type α-CePdZn and TiNiSi type β-CePdZn were measured at high pressure up to 14 GPa at room temperature using X-ray diffraction (XRD) and a diamond anvil cell. The pressure dependence of lattice constants and volume of α-CePdZn were found to be smooth without any discontinuity, and having a bulk modulus, B0, and its pressure derivative, B0′, of 67 GPa and 5.1, respectively. On the other hand, the a and b axes as well as volume of β-CePdZn were found to show anomalous pressure dependence at around 8 GPa. B0 and B0′ of β-CePdZn were 90 GPa and 2.1, respectively. These results suggest that a crossover in the electronic states is induced by applying pressure to β-CePdZn. The origins of these anomalous behaviors are discussed in connection with crossover and change in the topology of Fermi surface.