Dry process for synthesis of a phosphor by treatment under a fluorine atmosphere

A process for the dry synthesis of a luminophore of formula Ax[BFy]:C, A being a chemical element from Li, Na, K, Rb, Cs or a combination of at least two of these chemical elements, B being a chemical element from Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Hf, Y, La, Nb, Ta, Bi, Gd or a combination of at least two of these chemical elements, F being fluorine, C being a doping chemical element, x being the number of atoms of the element A and being equal to 1, 2 or 3, y being the number of atoms of the element fluorine and being equal to 5, 6 or 7,

• the process comprising the following stages:
• a) a stage of providing an initial composition, the initial composition comprising at least one first synthetic precursor A′, at least one second synthetic precursor B′ and at least one chemical doping source C′,
• b) a stage of heating the initial composition up to a fluorination temperature of between 200 and 550° C., the heating stage being carried out under an inert atmosphere or under vacuum,
• c) a stage of treatment under a fluorine atmosphere of the composition obtained on conclusion of the heating stage, comprising the following successive substages:
• c1) a substage of maintaining at the fluorination temperature,
• c2) a substage of cooling from the fluorination temperature down to a temperature of less than or equal to 150° C.,
• d) a stage of returning to ambient temperature under an inert atmosphere the composition obtained on conclusion of the stage of treatment under a fluorine atmosphere.