Strontium fluoride behaviour in fluoride melts in the presence of non-isomorphic carrier-lanthanum fluoride

It was shown that strontium fluoride (the microcomponent) coprecipitates with lanthanum fluoride in the systems LaF3-SrF2-MF (M = Li, Na, K, Rb, Cs) according to the Khlopin law. The coefficient of cocrystallization of strontium fluoride depends on the nature of the flux. In a system with lithium fluoride D = 0.18; with sodium fluoride 1.1; with potassium, rubidium, and cesium fluorides 3.9, 4.7, and 3.2, respectively. The observed changes in the coefficient of cocrystallization when the flux is replaced are explained on the basis of data on the types of fusibility diagrams of the investigated system by a change in the activity of the ions of the macro- and microcomponents on account of the formation of complex compounds of various strengths in the corresponding systems. A comparison of the data obtained on the cocrystallization of strontium and radium fluorides with lanthanum fluoride in the same systems resolves the question of the type of fusibility diagram of the binary system SrF2-RbF in favor of the presence of a compound in this system