OXYGEN SOLUBILITY IN LIQUID GALLIUM AND LIQUID INDIUM

The oxygen solubility in liquid gallium or liquid indium equilibrated with solid Ga2O3 or In2O3, respectively, was determined in an alumina crucible which was less reactive than the silica one. After establishment of an equilibrium between the liquid metal (gallium or indium) and an oxide (Ga2O3 or In2O3) formed on the surface of the metal during melting, the oxygen content in quenched gallium or indium was analyzed by the inert gas fusion-IR absorption method. The optimum conditions for oxygen extraction were decided for a furnace power and a bath composition. The temperature dependence of oxygen solubility in liquid gallium or liquid indium was expressed as the following equations: log (C (o) under bar/mass% in liquid gallium) = -6200/ T+2.61(+/-0.119) (T:1123 similar to 1523 K), log (C (o) under bar/mass% in liquid indium) = - 6600/T+3.77(+/-0.074) (T:1073 similar to 1373 K). Using the temperature dependence of the oxygen solubility in the present work and the standard free energy of formation of Ga2O3 or In2O3 in the literature, the standard free energy change for oxygen dissolution in liquid gallium or liquid indium could be represented as follows: 1/2O(2)(g)=(O) under bar(mass%, in liquid gallium), Delta G degrees = -2.45 x 10(5)+59.6T(J), 1/2O(2)(g)=(O) under bar(mass%, in liquid indium), Delta G degrees = -1.79 x 10(5)+33.8T(J).