Preparation method of red phosphors based on sulfide

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PURPOSE : Provided is a method for preparing a red phosphor based sulfide of alkali earth metal by coprecipitation and pH control, which does not use a separate flux for decreasing a temperature, and uses a mixture of hydrogen and nitrogen in place of noxious gases such as H2S or CS2, and thus is expected to have environmentally and economically excellences. CONSTITUTION : The method comprises the steps of (i) dissolving 0.5-0.9999 mole of precursor of alkali earth metal and 0.0001-0.5 mole of europium precursor into acid to obtain an acidic solution, dispersing the acidic solution into C1-C5 alcohol, and adjusting a pH of the solution to 3-5 to prepare a mixed metal solution, (ii) introducing an aqueous solution of sulfate and sulfide of period 3 metal having pH 8-10 to the mixed metal solution, to adjust a pH to 6-8, and then filtrating and drying the solution to prepare a precursor of phosphor based on alkali earth metal sulfide, and (iii) heating the precursor of phosphor at 600-1000 deg.C at the atmosphere of mixture of nitrogen and hydrogen gases. © KIPO 2007