Abstract: A mixed melt, which contains urea and/or a urea derivative and contains a metal compound, is prepared. The mixed melt is solidified, by heating, whereby the urea and/or urea derivative is decomposed, a precursor being thereby prepared. The thus prepared precursor is ground, and then the thus ground precursor is fired. The metal of the metal compound may be at least one kind of a metal selected from the group consisting of Al, B, Ba, Be, Bi, Ca, Cd, Cs, Ga, Ge, Hf, In, K, Li, Mg, Mo, Na, Nb, P, Rb, Si, Sn, Sr, Ta, Ti, V, W, Zr, and rare earth metals. A finely powdered phosphor free from inclusion of impurities and having uniform particle size is thus produced at a low cost and efficiently.

Abstract: A mixed melt, which contains urea and/or a urea derivative and contains a sulfur source and a zinc source, is prepared. A temperature of the mixed melt is raised, and a precipitate of zinc sulfide is thereby formed. The temperature of the mixed melt is raised even further, and a solid material containing the zinc sulfide is thereby formed. The solid material is fired, and organic constituents contained in the solid material are thus removed. Zinc sulfide particles having uniform particle size and free from inclusion of impurities are thus produced without any precipitant being added.

Abstract: A mixed melt, which contains urea and/or a urea derivative and contains a metal compound, is prepared. A temperature of the mixed melt is raised, and the mixed melt is solidified, a precursor being thereby prepared. The thus prepared precursor is ground, and then the thus ground precursor is fired. The metal of the metal compound may be at least one kind of a metal selected from the group consisting of Al, B, Ba, Be, Bi, Ca, Cd, Cs, Ga, Ge, Hf, In, K, Li, Mg, Mo, Na, Nb, P, Rb, Si, Sn, Sr, Ta, Ti, V, W, Zr, and rare earth metals. A finely powdered phosphor free from inclusion of impurities and having uniform particle size is thus produced at a low cost and efficiently.

Abstract: A mixed melt, which contains urea and/or a urea derivative and contains a sulfur source and a zinc source, is prepared. A temperature of the mixed melt is raised, and a precipitate of zinc sulfide is thereby formed. The temperature of the mixed melt is raised even further, and a solid material containing the zinc sulfide is thereby formed. The solid material is fired, and organic constituents contained in the solid material are thus removed. Zinc sulfide particles having uniform particle size and free from inclusion of impurities are thus produced without any precipitant being added.

Abstract: A method for coating inorganic particles with a metal compound is performed by the steps of: preparing a dispersion which comprises a metal salt and inorganic particles in a molten organic material which takes a solid form at 25° C., is converted into a polar liquid by heating and decomposes by further heating; and heating the dispersion, whereby coating the inorganic particles with a metal compound which is converted from the metal salt.