Low-temperature heat capacity and high-pressure stability relation of stishovite

Abstract

Isobaric heat capacity of stishovite was measured at 2-311 K by thermal relaxation method, and standard entropy of stishivite was determiend as 24.0 JK-1mol-1. Combining the datum with standard entropy of coesite and the enthalpy of coesite-stishovite transition, the equilibrium coesite-stishovite transition boundary was calculated. The results indicate that the calculated boundary is placed very close to the boundary determined by high-pressure X-ray diffraction method, but that the calculated boundary has a slope larger than that by the high-pressure experiments.