起電力法によるCo₃B, Co₂B, CoBの標準生成ギブス自由エネルギーの測定

抄録

The standard Gibbs free energies of formation of Co₃B, Co₂B and CoB have been determined in the temperature range from 1126 to 1360 K by measuring electromotive forces of galvanic cells having a solid oxide electrolyte. The results obtained are as follows:
(1) ΔG_f^° (Co₃B)=−66900−7.51T(±170 J/mol).
(T=1151∼1331 K)
(2) ΔG_f^° (Co₂B)=−70700−4.08T(±400 J/mol).
(T=1126∼1360 K)
(3) ΔG_f^° (CoB)=−77900+10.51T(±230 J/mol).
(T=1151∼1274 K)
(4) Co₃B decomposes to Co and Co₂B by a eutectoid reaction. The eutectoid temperature, which was calculated from the standard Gibbs free enegies of formation of Co₃B and Co₂B, was 1108 K.