LOW-TEMPERATURE 3-DIMENSIONAL THERMOLUMINESCENCE SPECTRA OF UNDOPED YVO4 SINGLE-CRYSTALS GROWN BY DIFFERENT TECHNIQUES

Three dimensional (3D) thermoluminescence (TL) spectra of two yttrium orthovanadate (YVO4) single crystals grown from YVO4 melt by the Czoch ralski (CZ) technique and one additional YVO4 crystal pulled from lith ium-metavanadate (LiVO3) flux by the top seeded solution growth (TSSG) method were investigated after x-ray irradiation, The TL spectra were recorded in the 200-800 nm wavelength and 20-300 K temperature ranges before and after annealing of the crystals in an oxygen atmosphere. I n spite of the different growth conditions the measured 3D TL spectra of the CZ samples show similar TL characteristics. The main TL emissio n appears around 450 nm, and between 200 and 250 K. Further weak emiss ions were also detected at 570, 600, 650, and 710 nm wavelengths, whic h might be attributed to unwanted impurities. The TL spectrum of the T SSG crystal markedly differs from that of the CZ crystals. On one hand the major TL appears at lower temperatures whereas on the other hand the emission spectrum exhibits a broader band around 500 nm, while the weak bands between 500 and 700 nm could not be detected, Based on the se observations the different defect structures in YVO4 crystals are d iscussed in the article emphasizing that 3D TL measurement is a useful practical tool for the characterization and identification of YVO4 cr ystals grown by different methods. (C) 1997 American Institute of Phys ics.