Pressure Dependence of the Structural Phase Transition Temperature in SrTiO₃and KMnF₃

The pressure dependence of the structural phase transition temperature, T a , in SrTiO 3 has been measured up to 30 kbar. The initial slope of 1.8 deg/kbar by Sorge et al. (1970) has been reaffirmed contrary to the prediction by Fossheim and Berre (1972): d T a /d p =0.5 deg/kbar. Above 8.5 kbar the transition temperature shifts nonlinearly with increasing pressure. As for the cubic-tetragonal transition temperature of KMnF 3 the measurements to 10 kbar show a linear shift: d T a /d p =3.9 deg/kbar. Above 10 kbar a deviation from linearity seems to set in.