Growth of Nd-doped NaY(WO₄)₂single crystals from nonstoichiometric melts

Abstract

The solidification behavior in the Na2WO4–Y2(WO4)3 pseudo-binary system has been investigated to find out the composition of a starting material to grow single crystals of NaY(WO4)2 using the Czochralski technique. It is demonstrated that a starting charge rich in Y2(WO4)3 restricts the formation of impurity phases and may be useful in growing single crystals of a stoichiometric composition. Crystal growth experiments were carried out on undoped and Nd-doped NaY(WO4)2 employing the starting charges with 53 mol% of Y2(WO4)3. The x-ray diffraction data of as-grown crystals were refined using the GSAS program based on the Rietveld refinement. The effective segregation coefficients of the elements measured by the x-ray fluorescence technique revealed the stoichiometric composition of the as-grown Nd:NaY(WO4)2 crystals. The presence of elements in the grown crystals and their valance state were studied using x-ray photoelectron spectroscopy.