Abstract: A method for producing a gallium nitride crystal includes growing a gallium nitride crystal 5 by dissolving nitrogen in a mixed melt including gallium and sodium, and collecting the gallium 55 separated from an alloy 51 including the gallium and the sodium by reacting the alloy 51 and a liquid 52 that ionizes the sodium and separating sodium ions and the gallium 55 from the alloy.

Abstract: A method for growing a silicon single crystal by a Czochralski method, includes: conducting preliminary examination of growth conditions under which crystal collapse does not occur, the preliminary examination being based on a correlation between presence or absence of the crystal collapse in the silicon single crystal and a position at which an internal stress in the crystal when the silicon single crystal is grown will exceed a prescribed threshold, the position being away from a crystal growth interface; and growing the silicon single crystal in accordance with the growth conditions under which the crystal collapse does not occur, the growth conditions being determined from the preliminary examination. The method can grow a silicon single crystal while crystal collapse is effectively prevented.

Abstract: A method of producing a double-doped scintillation crystal is provided. Czochralski method is used to grow a double-doped single crystal boule. The double-doped single crystal boule is a single crystal boule of rare-earth silicate double-doped with cerium (Ce) and calcium (Ca) or magnesium (Mg). The double-doped single crystal boule is subjected to a thermal annealing process in a furnace. A yield of pixel samples of the double-doped scintillation crystal is improved after a processing process, and the present invention achieves low producing cost, high yield, less crystal fragmentations, high luminescence intensity and short decaying time.