Method of preparing barium fluorohalide phosphor

Abstract

A method of preparing a barium fluorohalide phosphor including a mixing step in which phosphor materials are mixed, a firing step in which a resulting mixture of phosphor materials is fired, an annealing step, and a cooling step in which the mixture of phosphor materials is cooled to the ordinary temperature. In the firing step, after the mixture of phosphor materials has been fired at a constant temperature, an atmosphere at the time of the firing is removed while the constant temperature is maintained, and is replaced with an atmosphere different from the atmosphere at the time of the firing, and thereafter, annealing is carried out. In the cooling step, the atmosphere at the time of the firing is removed and replaced with a first different atmosphere, and then first cooling is carried out. Further, the first atmosphere is removed and replaced with a second atmosphere, and then second cooling is carried out. Alternatively, in the cooling step, the atmosphere at the time of the firing is removed and replaced with vacuum or a neutral gas atmosphere, and then cooling is carried out.