Thermogravimetric Study of MHgO2 (M=Ca, Sr, Ba) under Controlled Oxygen and Mercury Partial Pressures and Related Thermodynamics

A novel method of thermogravimetry under controlled mercury and oxygen partial pressures was developed, which allowed us to obtain the precise thermodynamical data for the equilibrium MHgO2(s) <->MO(s) + Hg(v)+1/2O2 (M =Ca, Sr, and Ba). Temperature dependencies of equilibrium constants Kp are described by the equations: log Kp(CaHgO2) =- (9424±540)/T + (10.28±0.57), (888–1013 K); log Kp(SrHgO2)=-(10197 ±890)/T + (10.10±0.83), (1043–1118 K); log Kp(BaHgO2) = (10474±730)/T+(9.94±0.64), (1098–1163 K). Thermal stability of mercurates increases in the order CaHgO2, SrHgO2, BaHgO2