Eu valence state and valence transition in Eu(Pd_1-xPt_x)₂Si₂

We examine the temperature dependence of the Eu valence and lattice parameters for Eu(Pd_1-x Pt_x)₂Si₂ by means of x-ray absorption spectroscopy (XAS) and x-ray diffraction, respectively. Strong temperature dependence of the Eu valence was observed for Eu(Pd_1-xPt_x)₂Si₂. Combining the Moessbauer effect data and XAS results, we estimated the Eu valence as a function of temperature. It is shown that the Eu valence in the ground state shows very little sensitivity to x for 0≤x≤0.10. In the temperature dependence of the Eu valence, the compound with x = 0.05 undergoes a continuous valence change, while the one with x = 0.15 shows a first-order valence transition. The factors determining the Eu valence in Eu(Pd_1-xPt_x)₂Si₂ are discussed.