Abstract
The elastic constants of tetragonal ZnF2 were measured at room temperature from ambient conditions to 10 kbar. The values at 1 bar and 10 kbar are (in 1011 dynes/cm2) CS=(C11C12)2 softens with increasing pressure. C44 shows a weak pressure dependence. Similar behavior has been observed in NiF2, TiO2, and in the distorted rutile structure crystal TeO2. The soft CS is believed to be a precursor to a pressure-induced orthorhombic distortion.