A thermodynamic methodology was put forward to assess the standard hea
ts of formation and absolute entropies of silicon oxides, based on var
ious thermal behaviors such as decomposition temperatures. The standar
d heats of formation at 298 K thus calculated are 1345.53, 426.08 and
342.84 kJ/mol for Si2O3(am), SiO(am) and Si2O(am), respectively. The s
tandard entropies obtained by this method are 105.67, 61.60 and 133.08
(J/K)/mol for Si2O3(am), SiO(am) and Si2O(am) at 298 K, respectively.
Using these data, the equilibrium phase relations in the Si-O system
have been computed and shown graphically as a function of oxygen poten
tial for the temperature range of 298-2500 K.