The method of chemical vapour transport (CVT) in a temperature gradient provides a versatile tool for synthesis, crystallization and purification of anhydrous transition metal phosphates. The whole span of now more than 60 phosphates grown on laboratory scale via the gas phase might be visualized by the thermally labile Pd2P2O7 and RhPO4, some low melting ultraphosphates (e. g.: CuP4O11, ZnP4O11) and a series of phosphates containing transition metals in otherwise not easy accessible oxidation

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... tates (e. g.: TiPO4, V2O(PO4), Cr3(PO4)2, Cr2P2O7). The experiments are carried out in sealed silica ampoules at temperatures between 500 and 1100°C, depending on volatility and thermal stability of the phosphate. Plein chlorine or iodine in combination with a few mg of metal, metal phosphide or phosphorus as reducing agents have led to the best results with respect to crystal size, quality and growth rate. Heterogenous solid/gas as well as solid/solid equilibrium reactions determining the transport process will be discussed.