KMg0.09Fe1.91(PO4)2

KMg0.09Fe1.91(PO4)2, potassium [iron(II)/magnesium] iron(III) bis(orthophosphate), is a solid solution derived from compounds with general formula KM IIFe(PO4)2 (M II = Fe, Cu), in which the Mg atoms substitute Fe atoms only in the octa­hedrally surrounded sites. The framework of the structure is built up from [FeO5] trigonal bipyramids and [MO6] (M = (Fe, Mg) octa­hedra sharing corners and edges and connected by two types of bridging PO4 tetra­hedra. The K+ cations are nine-coordinated and are situated in channels running along [101]

Synthesis and Luminescence Properties of Pr³⁺-Doped BiPO₄ Polycrystals

The results of synthesis, crystal structure characterization and luminescence properties study of the Pr³⁺-doped bismuth orthophosphate, BiPO₄, polycrystals are reported. It was found that doping of bismuth orthophosphate with praseodymium of concentration more than 1% leads to phase transition of BiPO₄ from so-called "high-temperature monoclinic" to "low-temperature monoclinic" structure. At room temperature studied samples revealed intensive red luminescence caused by radiation electronic transitions in the Pr³⁺ ions under their intrinsic f → f excitation at ³H₄→ ³P₁+¹I₆ absorption transition. Influence of phase transformation as well as multi-phonon and cross-relaxation processes on the luminescence of the Pr³⁺-doped BiPO₄ compounds were discussed