Solubilities of lanthanum oxide in fluoride melts: Part I. Solubility in M3AlF6 (M = Li, Na, K)

Solubility of lanthanum oxide was measured by thermal analysis. The solubility in alkali cryolites is rather high, because of chemical reactions between lanthanum oxide and cryolites. In Li3AlF6–La2O3, alumina precipitates, in the other systems the mixed oxide LaAlO3 is formed. In La2O3–Li3AlF6 the eutectic point is at 9.5 mol% La2O3 and 755 °C. The eutectic points in La2O3–Na3AlF6 and La2O3–K3AlF6 are at 11.5 mol% La2O3, and at 937 and 934 °C, respectively.