RARE EARTH BORATE AND ITS PRECURSOR, PREPARATION PROCESSES AND USE OF BORATE AS LUMINOPHORE

The present invention relates to a rare-earth borate, to a precursor thereof, to processes for their preparation and to the use of this borate as a luminophore.The rare-earth borate and the precursor thereof are characterized in that they are in the form of cubic, parallelepipedal or spherical particles and in that they have a dispersion index of not more than 0.8. According to one embodiment of the invention, the borate is a red luminophore.The process for the preparation of the precursor is characterized in that a rare-earth carbonate or hydroxycarbonate is reacted with boric acid, the reaction medium being in the form of an aqueous solution. The borate is obtained by calcination of the precursor.