$BaThO_3$ are known to be excellent proton conductors which was potential candidates as electrolytes in hydrogen concentrators and fuel cells. In this study, Gibbs formation free energy of $BaThO_3$ from elemental oxides have been measured in the temperature range of 853-903K using a $CaF_2$ solid electrolyte galvanic cell.
Galvanic cell consisted of
$CaO + CaF_2 ∥ CaF_2 ∥ BaThO_3 + ThO_2 + BaF_2$.
Measured EMF gave Gibbs free energy of the following reaction,
$CaF_2 + BaThO_3 = CaO + BaF_2 + ThO_2$.
Gibbs free energy change for reaction
$CaO + BaF_2 = BaO + CaF_2$
is obtained from the thermodynamic table.
So we have following reactions.
$BaThO_3 = BaO + ThO_2$.
From this data, we obtained the gibbs formation free energy of $BaThO_3$.
