PRODUCTION OF RAW FOR PRODUCING BETA-TYPE BARIUM METABORATE SINGLE CRYSTAL AND PRODUCTION OF SAID SINGLE CRYSTAL

摘要

PURPOSE:To obtain a raw rod capable of producing a high-quality and large- sized single crystal by obtaining a beta-type BaB2O4 crystal with the flux method, crushing and forming the crystal, and sintering the formed product in an oxygen atmosphere. CONSTITUTION:The beta-type barium metaborate crystal is obtained by the flux method wherein the crystal is deposited from the molten salts of barium chloride and boric acid. The crystal is crushed, and formed by the rubber-press method, etc. The formed product is primarily sintered preferably at 750-850 deg.C in an oxygen atmosphere, and the sintered product is crushed, formed, and secondarily sintered at 850-1095 deg.C to obtain the raw rod for producing a beta-type BaB2O4 single crystal. The title crystal is grown under the raw rod at 920 deg.C in a solvent consisting of 25-35mol% BaO, 40-50mol% B2O3, and 20-30mol% Na2O in accordance with the floating zone method such as the IR concentrated- heating method. The growth rate is preferably controlled to 0.1-0.3mm/h.