BISMUTH GERMANATE SINGLE CRYSTAL BLOCK FOR SCINTILLATOR AND PRODUCTION THEREOF

摘要

PURPOSE:To improve resolving power of energy in scintillation by eliminating strain formed in growing process of the title single crystal and processing process of block. CONSTITUTION:Cylindrical single crystal of Bi4Ge3O12 is obtained from melt of Bi2O3 and GeO2 powder by Czochralski single crystal pulling method, a block of desired size is cut out from the single crystal, a face to be brought into contact with a photomultiplier tube is subjected to mirror polishing and other five faces are roughly polished. Then the block is etched with a strong acid or heat-treated in an O2 atmosphere, strain layers on the surface of crystal are eliminated until resolving power of energy reaches =90% value before elimination. The temperature of the heat treatment is preferably 750 deg.C to the melting point.