Molar Gibbs energy formation of RbUO3(s)

The molar Gibbs energy of formation of RbUO3(s) was determined by measuring the oxygen pressure over the phase field, RbUO3(s) + Rb2U2O7(s) + Rb2UO4(s), using a solid oxide electrolyte galvanic cell in the temperature range 920 to 1100 K and the partial pressure of rubidium using the Knudsen effusion mass loss method in the temperature range 1305 to 1459 K. The oxygen potential and the rubidium potential existing over the phase field can be respectively given by Delta mu(O-2) +/- 0.4(kJ mol(-1)) = -531.6 +/- 0.2026T(K) and Delta mu(Rb) +/- 0.6(kJ mol(-1)) = -152.7 + 0.018T(K).