Novel rare earth fluorosulfides or oxyfluorosulfides, their production process and their use as pigments for coloring

摘要

The invention concerns novel rare earth fluorosulphides using four modes of production, novel rare earth oxyfluorosulphides, their preparation methods and their use as dyeing pigment. The fluorosulphide of the first mode corresponds to the formula (LnSF) (Ln represents a rare earth) and has a particle average size of more than 5 mu m. That of the second mode is a mixed rare earth fluorosulphide of formula (Ln, Ln')SF and in the form of a solid solution. The fluorosulphide of the third mode, in a first embodiment, comprises at least an alkaline element and has a LnSF-type structure, the rare earth being selected among yttrium and from the group ranging from lanthanum to erbium inclusively. In a second embodiment of said third mode, the fluorosulphide comprises at least an alkaline element, it has a space group hexagonal structure P6322, the rare earth likewise belonging to the group ranging from holmium to lutetium inclusively, also including yttrium. The fluorosulphide of the fourth mode corresponds to the formula Ln2AF4S2 wherein A is an alkaline-earth. The oxyfluorosulphide corresponds to the formula Ln3S2F3O wherein Ln represents at least a trivalent rare earth.