Influence of Accidental Impurities on the Spectroscopic and Luminescent Properties of ZnWO 4 Crystal.

Special techniques for deep purification of ZnO and WO 3 have been developed in this work. A ZnWO 4 single crystal has been grown by the Czochralski method using purified ZnO and WO 3 chemicals, along with the ZnWO 4 crystal-etalon, which has been grown at the same conditions using commercially available 5N ZnO and WO 3 chemicals. The actual accidental impurities compositions of both the initial chemicals and the grown crystals have been measured by inductively coupled plasma mass-spectrometry. A complex of comparative spectroscopic studies of the crystals has been performed, including optical absorption spectra, photo-, X-ray-, and cathodoluminescence spectra and decay kinetics, as well as the photoluminescence excitation spectra. The revealed differences in the measured properties of the crystals have been analyzed in terms of influence of the accidental impurities on these properties.