For breeding of tritium, LiNbO3(s) and Li3NbO4(s) are the most efficient materials because of their suitable nuclear behavior. In the present study, the lithium niobates have been synthesized by solid state route and characterized with X-ray diffraction technique. The suitability of this oxide breeder was not only based on their nuclear suitability but also thermodynamic stability plays an important role. In this present work thermodynamic stability of these compounds have been determined in terms Gibbs free energy of formation using knudsen effusion mass spectrometric technique and the heat capacity of LiNbO3(s) and Li3NbO4(s) has been experimentally measured by differential scanning calorimeter. The free energy formation of LiNbO3(s) and Li3NbO4(s) are given below:
ΔGf (LiNbO3, s, T) ± 6/kJ mol-1 = -1264.33 + 0.324193.(T/K). (694 ≤ T ≤ 869)
ΔGf (Li3NbO4, s, T) ± 7/kJ mol-1 = -1849.11 + 0.49260.(T/K) (758 ≤ T ≤ 877).