Structural and spectroscopic characterization of the double tungstate crystals doped with and grown by the micro-pulling down technique

NaBi1−xY bx(WO4)2 fibres single crystals were successfully grown by micro-pulling down technology (MPD). The Y b3+-doped NaBi(WO4)2 fibres single crystals have been pulled using MPD technique with controlled diameter and stationary stable growth conditions corresponding to flat crystallization interface with meniscus length equal to the fibre radii and pulling rate range [ 6–48 mm h−1]. We have determined the single phase field of NaBi1−xY bx(WO4)2 for x≤0.3. The lattices parameters decrease as a function of Yb3+ substitution in Bi3+ sites. The melt behaviour has been study by DTA/TG analysis. We have found that the stoichiometric compounds NaBi(WO4)2 melt congruently at 935 ∘C. The fibre diameters varied from 0.5 to 1 mm depending on the capillary die diameter, pulling rate and the molten zone temperature. Complementary Y b3+ spectroscopic characterization in the NaBi(WO4)2 lattice has been done by IR emission measurements under laser pumping at room temperature.