Studies of ways to reduce defects in CdWO4 single crystals

Studies are reported of the nature and formation conditions of structural defects affecting principal working characteristics of cadmium tungstate single crystals (macro- and microinclusions, scattering centers, block structure, twinning, violations of stoichiometry). It is shown that macro- and microinclusions are morphologically related to the crystal growth from the supercooled melt and are caused by the capture of crystal-forming components as intrinsic impurities by the growing crystal. Macro- and microinclusions are shown to form layered structures parallel to the (1 0 0) planes, which are also twinning planes. Ways are proposed to improve structural perfection of the crystals, providing for their high functional characteristics. Accounting for the studied features of intrinsic defect formation, optimum crystallographic directions were suggested for the crystal growth and subsequent cutting into scintillation elements with high and reproducible functional characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.