Preparation of monocrystals of nonstoichiometric fluorite phases M1-xRxF2+x (M = Ca,Sr,Ba; R - rare earths) by Bridgman-Stockbarger method

Modern state of methods for the preparation of monocrystals of highly nonstoichiometric fluorite phases by the Bridgman-Stockbarger method is considered. Equilibrium distribution coefficients of all availability rare earth ions in MF2 in cse of oriented crystallization of the melts are investigated. Problems of pyrohydrolysis suppression during crystallization, problems of homogenization of fluoride melts of multicomponent compostion in their relation with crystal growth mechanisms are considered. Processes of axial and radial heterogeneity formation in monocrystals are analyzed, conditions for homogenous distribution of impurity component are defined. Certain problems of technical instrumentation of growing experiment as applied to fluorite nonstoichiometric phases are discussed. 96 refs.; 4 figs.; 2 tabs