Colloidal dispersion useful for making transparent luminescent materials comprises rare earth metal

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Colloidal dispersion comprising rare earth metal phosphate particles with a rhabdophan structure and a polyphosphate is new. - Independent claims are also included for the following : - (1) producing a dispersion as above by heating a medium containing a rare earth metal (REM) salt and a polyphosphate in amounts such that the phosphorus/REM ratio is at least 3, and removing residual salts; - (2) transparent luminescent material based on REM phosphate particles with a size of up to 250 nm and a phosphorus/REM ratio above 1; - (3) transparent luminescent material comprising lanthanum cerium phosphate nanoparticles, lanthanum cerium terbium phosphate and yttrium vanadate, where the particles have a phosphorus/REM ratio above 1 and the luminescent material emits white light with defined chromaticity coordinates when excited at wavelengths of up to 380 nm; - (4) luminescent system comprising a material as above and an excitation source.