Mixed phosphates K2MIIIMV(OPO4)2: Heterovalence-substituted analogs of KTiOPO4

A series of heterovalence-substituted analogs of KTiOPO₄ of the general composition K₂M^IIIM^V(OPO₄)₂ (M^III = Cr, Fe, In; M^V = Nb, Ta) were synthesized by crystallization from melts and by solid-phase reactions. Influence of the nature of tri-and pentavalent metals on the conditions of preparation and on the features of phase formation of substituted mixed phosphates was examined. The compounds obtained were characterized by X-ray diffraction analysis and by diffuse reflection spectroscopy.