Thermodynamic stability of CaThF6(cr) by transpiration and e.m.f. techniques

In the present paper, we report the standard molar Gibbs energy of formation for CaThF₆ measured by gas equilibration and e.m.f. methods. The HF(g) vapour pressure over the equilibrium reaction: ({text{CaThF}}_{6} left( {text{cr}} right) + 2 {text{H}}_{ 2} {text{O}}left( {text{g}} right) = {text{CaF}}_{2} left( {text{cr}} right) + {text{ThO}}_{2} left( {text{cr}} right) + 4{text{HF}}left( {text{g}} right)) has been measured using transpiration technique. The above reaction mechanism has been established employing TG and XRD techniques. A fluoride e.m.f. cell: (−)Pt, CaF₂(cr) + ThOF₂(cr) + CaThF₆(cr) |CaF₂(cr)| NiO(cr) + NiF₂(cr), Pt(+) has been constructed to measure Gibbs energy of formation of CaThF₆ (cr) using CaF₂ (cr) as a solid electrolyte. The isobaric heat capacity ({text{Cp}}_{text{m}}^{{circ }} left( T right)) of the compound has been measured using differential scanning calorimetric technique. Based on the experimental results, thermodynamic functions for CaThF₆ have been generated.