Morphotropism of Rare-Earth Orthoborates RBO3

Resumo

A diagram in the coordinates “temperature-ionic radius” is built for polymorphic and morphotropic transitions in a series of REE orthoborates. The stability fields are determined for the structural types of calcite, aragonite, vaterite, pseudo-vaterite, H-LaBO₃, and L-SmBO₃. The temperatures of some metastable phase transformations are estimated.