Monoclinic zinc monotungstate Yb3+,Li+:ZnWO4: Part I. Czochralski growth, structure refinement and Raman spectraстатья
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Дата последнего поиска статьи во внешних источниках: 4 февраля 2021 г.
Аннотация:We report on the growth of a co-doped divalent-metal monotungstate crystal, Yb3+,Li+:ZnWO4, its structurerefinement, thermo-mechanical properties and polarized Raman spectra. Yb3+,Li+:ZnWO4 crystals are grown bythe Czochralski method using Pt/Rh and Pt crucibles. The nature of crystal coloration is discussed and assigned tocolor centers based on oxygen vacancies as well as Fe2+(Fe3+) species and, possibly, other uncontrolled impuritiesof transition metal ions. Oxidizing annealing at 800 ◦C helps to improve the transparency of Yb3+,Li+:ZnWO4 leading to a weak residual pink coloration. Yb3+,Li+:ZnWO4 was confirmed to be monoclinic (sp. gr. P2/c– C42h, No. 13) with lattice constants a = 4.702(2) Å, b = 5.718(6) Å, c = 4.930(4) Å and β = 90.713(5)◦. Thecoefficients of linear thermal expansion are α[100] = 11.71, α[010] = 9.90 and α[001] = 7.01 [10 6 K 1]. Themelting point of the crystal is at 1166 ◦C and no thermal effects are found below the melting point. The Yb3+,Li+:ZnWO4 crystal shows intense and strongly polarized Raman spectra with the most intense mode at 906.0 cm 1assigned to the W – O stretching vibrations in the [WO6] octahedra. It is thus a promising gain medium for laseremission at ~1 μm and for self-Raman frequency conversion.