METHOD OF ISOLATING AND REFINING CUBIC SPINEL-TYPE SILICON NITRIDE

摘要

PROBLEM TO BE SOLVED: To provide a method of isolating and refining cubic spinel-type silicon nitride, by which unreacted low pressure phase silicon nitride contained in the cubic spinel-type silicon nitride as an impurity can be separated and the purity of the cubic spinel-type silicon nitride can be heightened. SOLUTION: The isolation and refining of the cubic spinel-type silicon nitride comprises accommodating a mixed power 12 comprising the cubic spinel-type silicon nitride and the low pressure phase silicon nitride and a mixed acid solution 13 comprising hydrofluoric acid and nitric acid or sulfuric acid in a reaction vessel 1 and reacting them while heating. Thereby, the low pressure phase silicon nitride reacts with the hydrofluoric acid and the unreacted low pressure phase silicon nitride in the cubic spinel-type silicon nitride is isolated and the cubic spinel-type silicon nitride is refined. The temperature at which the mixed acid solution is allowed to act is preferably 110 to 160 deg.C. It is preferable that both of the cubic spinel-type silicon nitride and the low pressure phase silicon nitride are powders and the particle diameters of each powder are <=10μm.