Cylindrical Approximation and the α—β Quartz Transition

Pippard's cylindrical approximation to the thermodynamics of a λ‐point transition is applied to the α—β quartz inversion. Mayer's data on the thermal expansion and on the elastic constants of quartz, coupled with Moser's specific heat data, permit two independent estimates of (dT/dP)λ. The value of (dT/dP)λ derived from the thermal expansion and elastic constant data agrees to within 2.5% with Yoder's experimental value.