Thermodynamic properties of CaTiF5(s)

Calcium titanofluoride CaTiF5(s) was prepared by solid-state reaction of CaF2(s) with TiF3(s) and characterized by X-ray diffraction method. The standard molar isobaric heat capacity (Cp,m∘) of CaTiF5(s) was determined by a power compensated differential scanning calorimeter in the temperature from 230 K to 710 K. A solid-state galvanic cell with CaF2 as electrolyte was used to determine the standard molar Gibbs energy of formation (ΔfGm∘) of CaTiF5 in the temperature range from 803 K to 1005 K. The galvanic cell can be depicted as:(-)Pt,O2(g,101.325kPa)/{CaO(s)+CaF2(s)}//CaF2//{CaTiF5(s)+CaTiO3(s)}/O2(g,101.325kPa),Pt(+)The second law analysis of present data were carried out to derive the standard entropy Sm∘(298.15K) and the enthalpy of formation ΔfHm∘(298.15K) and the values derived are 68.7 J · K−1 · mol−1 and −2848.4 kJ · mol−1, respectively.