THERMOCHEMICAL PROPERTIES OF SRSIO(G) AND SRBO2(G)

The vaporization behaviour of strontium borosilicate glass melt with a composition of SrO·B2O3·SiO2 has been studied by a mass-spectrometric Knudsen-effusion method in the temperature range 1337 K to 1602. Vapours of Sr(g), SrSiO(g), SrBO2(g), BO(g), B2O2(g), B2O3(g), and SiO(g) have been identified. From the gaseous equilibria involving SrSiO(g) and SrBO2(g), their molar enthalpies of formation and dissociation have been determined to be ΔfHmo(SrSiO, g, T → 0)/(kJ·mol-1) = -(314 ± 18), Do(SrSiO, T → 0)/(kJ·mol-1) = (377 ± 16), ΔfHmo(SrBO2, g, 298.15 K)/(kJ·mol-1) = -(637 ± 9), and Do(SrBO2, 298.15 K)/(kJ·mol-1) = (517 ± 8), respectively. © 1990.