Kinetic study of the solution-mediated transformation of orthorhombic barium fluoride into cubic barium fluoride

The transformation of a-(orthorhombic)BaF 2 into β-(cubic)BaF 2 was studied by X-ray diffraction analysis, scanning electron microscopy and particulate analysis of the solid phase, and chemical analysis of the liquid phase of the samples drawn off the suspension at various transformation times t T . The transformation process was found to take place by dissolution of the unstable orthorhombic modification and growth of the microcrystals of α-BaF 2 present at constant supersaturation. Following such a model of the transformation process, the kinetic equation of the transformation was derived and correlated with experimental data. The activation energy of the crystal growth of β-BaF 2 was calculated.