Growth And Properties Of YGdVO₄ Mixed Crystals

Diode-pumped Solid-state Lasers (DPSSL) have been widely used in the fields of military, medical treatment, optical communication, material processing, laser measurement, etc, due to its advantages such as compactness, long lifetime, all-solid state, high efficiency and high stability. Searching for more efficient laser crystals has become a hot point since such materials play important roles both in laser designing and laser application.Single crystals of rare earth orthovanadate (REVO₄) have been proved to be excellent laser materials. Yttrium Gadolinium vanadate crystal (YGdVO₄) is a new hot laser material. It has good laser properties such as lager wide absorption band, high thermal conductivity and low threshold. This crystal is a promising material in high power laser application. Yb³⁺-doped materials and Er³⁺-doped materials have many advantages. However, studies on Yb:YGdVO₄ crystal and Er,Yb:YGdVO₄ crystal are scarce by far. So it is necessary to carry out research work on Yb:YGdVO₄ crystal and Er,Yb:YGdVO₄ crystal.It was investigated on the crystal growth, structure, thermal properties, optical properties and crystal defects of Yb:YGdVO₄ crystal and Er,Yb:YGdVO₄ crystal in this thesis.The polycrystalline materials were synthesized by the liquid-phase method. Using the purified polycrystalline materials and with a strict synthesis control. Excellent single crystals were grown by the Czochralski method. The experiment phenomena during crystal growth have been discussed. The crystal structure and growth morphology were analyzed. X-ray powder diffraction (XRPD) results show that the structure of the crystals is as same as ZrSiO₄. The lattice constants of the crystals were calculated. Segregation coefficients were measured by X-ray fluorescence analysis method. The density of crystals was measured by using buoyancy method at room temperature. The thermal diffusion coefficient of the crystals were measured by the crystal pulse method. Thermal expansions of the crystals were measured. Optical absorption property of the crystals were investigated in spectral regions of 300-1800 nm at room temperature. Optical microscopy and chemical etching were used to observe and investigate the defects of the crystals. Mechanism of defects formation was discussed and corresponding solutions were also presented so as to improve crystal quality.