Anomalous structural states of rare-earth oxides in solid-phase synthesis during continuous heating

The kinetics of solid-phase synthesis of complex rare-earth (RE) oxides from an amorphous precursor state during continuous heating is studied by X-ray diffraction. Using the synthesis of RE borates (ReBO₃) as an example, it is shown that a continuous heating of such precursors stimulates the formation of new phases which are unknown in an equilibrium state of one rare-earth element but known for other rare-earth borates. It is established that the regime of continuous heating during solid-phase synthesis of garnets (Re ₃ M ₅O₁₂) exhibiting the only crystal phase state for all rare-earth atoms results in an accelerated growth of crystallites and that the higher the heating rate the higher the growth rate.