On the valence stability of Eu in the laves phase compounds Eu1-xPtxPt2 under high-pressure

High-pressure Mössbauer studies of the ¹⁵¹Eu resonance in Eu_1-xPt_xPt₂ (x = 0;0.143;0.25) have been performed between 4.2 and 300 K. A linear decrease in the magnitude of the interconfiguration excitation energy E_exc on the Eu²⁺-site with decreasing lattice constant was found (?|E_exc|/?lnV = 1.6 x 10⁴K). The isomer shift for EuPt₃ at 70 kbar and 4.2 K shows that the Eu atoms on the Eu²⁺-site are no longer pure divalent but have ? 5% admixture of the Eu³⁺ cofiguration.