Search for impurity phases of Nd3+: YVO4 crystals for laser and luminescence applications

Structural investigation of the Y2O3-V2O5 system was undertaken with the ai m of characterizing possible segregated phases appearing during the synthes is of pure and doped yttrium vanadate. Nd3+ :YVO4 single crystals obtained by LHPG and flux growth techniques were studied by high spatial resolution micro-Raman probe (up to 1 mu m in the X-Y plane) spectroscopy. The confoca lity of microscope coupled to the Raman microprobe allowed us to select the in-depth resolution of the probe. By mapping several single crystals grown with different methods, a segregated phase was identified in the Aux grown crystal, about 70 mu m below the surface. Micro-Raman maps of powder sampl es prepared by solid state reaction starting from 4Y(2)O(3)-V2O5 and 5Y(2)O (3)-V2O5 mixtures gave evidence of this phase. The spectral features are ve ry similar to the precipitate found in YVO4 : Nd3+ single crystal. (C) 1999 Elsevier Science B.V. All rights reserved.