D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

E. N. Mozhevitina, Researcher at the Department of Crystals Chemistry and Technology, Candidate of Chemical Sciences

D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia¹ ; Prokhorov General Physics Institute of RAS, Moscow, Russia²:

K. A. Subbotin, Senior Lecturer at the Department of Crystals Chemistry and Technology¹, Head of the Laser Crystal Spectroscopy Laboratory², Candidate of Technical Sciences, e-mail: soubbot1970@gmail.com
A. I. Titov, Graduate Student¹, Engineer of Laser Crystal Spectroscopy Laboratory²

Prokhorov General Physics Institute of RAS, Moscow, Russia:
D. A. Lis, Researcher at the Laser Crystal Spectroscopy Laboratory

Concentrations of 64 random impurity elements into the source chemicals of tungstic oxide, zinc oxide and ytterbium sesquioxide from different manufacturers were determined by inductively coupled plasma mass spectrometry. Single crystals of zinc tungstate, both nominally pure ZnWO₄ and ytterbium ionactivated Yb:ZnWO₄, were grown in air by Czochralski method from platinum crucibles using different combinations of initial reagents. The analysis of optical absorption spectra of the grown crystals has showed that the total absorption of crystals includes two components. The first one is removed by prolonged hightemperature oxidative annealing of crystals and is probably determined by color centers based on oxygen vacancies formed as a result of insufficient oxidazing potential of the growth atmosphere. The second component is not removed during annealing and probably depends upon the impurity ions, since correlation between concentrations of random impurities in the source chemicals and the nature of the second component of optical absorption of crystals has been established. Analysis of both obtained results and the literature suggests that ions of trivalent manganese serve as an absorbing center, and its absorption cross-section is abnormally large.

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