Solid solution with fluorite structure in the CaF2 ‐ LaF3 system

Abstract

AbstractThe phase equilibrium of fluorite Ca1−xLaxF2+x solid solutions in the CaF2 ‐ LaF3 system is investigated by means of DTA and X‐ray analysis. The phase diagram of his system is of eutectic type with limited solid solutions with the structure of components. The eutectic coordinates are 1311°C and 58 mole% of LaF3. The saturation line of fluorite solid solution has an anomalous S‐shape. The elementary cell parameter of this solution has been approximated by the parabolic equation a = ao + 0.597x + + 0.134x2, where ao = 5.46295 Å denotes the parameter of CaF2 elementary cell.Both dc/from 20 to 450°C/and ac/from 450 to 600°C/electrical conductivities were measured at concentrations covering almost whole region of the Ca1−xLaxF2+x solid solution formation. They are characterized by increasing conductivity and decreasing activation energy with increasing LaF3 concentrations. In samples with x > 0, 11 an increase of electrical conductivity due to aging was observed.