Growth And Properties Of Yb: GdV_1-xNb_xO₄ Crystals

This thesis reports the growth, thermal performance and spectral properties of GdV_1-x Nb_xO₄ and Yb: GdV_1-xNb_xO₄ crystals. The polycrystalline materials were synthesized by the liquid-phase reaction method and the state-phase reaction method. The single crystals were grown by the Czochralski method and the growth condition, atmosphere and annealing technology were investigated. The segregation coefficients of the dopant ions in Yb: GdV_1-x Nb_xO₄ crystals were calculated in terms of the component analyses by XRF and ICP separately. The segregation coefficient of Nb⁵⁺ is 0.25 and the segregation coefficient Yb³⁺ is 0.63-0.78. Doping of Nb⁵⁺ makes the laser damage threshold and the thermal conductivity reducing. Doping of Yb³⁺ makes the thermal expansion coefficient and the thermal conductivity decreasing and increasing separately. The absorption spectra, fluorescence spectra, fluorescent decay curves and Raman spectra have been measured at room temperature, from which the Stark levels of the Yb³⁺ ion were concluded. The spectra parameters of these crystals can be calculated by the method of reciprocity and the F-L formula, from which we can draw the conclusion that the optimum doped concentration of Nb⁵⁺ is 2.50at% and the optimum doped concentration of Yb3+in the GdV_0.9625Nb_0.0375O₄ crystal is 8.53at%. After analyzing the Raman spectra, the effect of the doping of Nb⁵⁺ on the Raman spectra was discussed.