Nuclear quadrupole resonance and nuclear magnetic resonance studies of K2PtCl6 type mixed crystals

Abstract

Phase transitions from cubic to lower symmetry phases in antifluorite (K₂PtCl₆) structures have been ascribed to lattice mode-softening. We study the effect of impurities on lattice vibrations and transition temperatures in such structures. For mixed rhenates we find a lowering of the frequency of the lattice vibrations with increasing impurity content and a corresponding increase in transition temperature. For mixed stannates the n.q.r. signal disappears at high temperature, perhaps due to reorientational motion of the stannate anion.