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Research on Growth and Properties of BaWO4 Crystal

Author: LiXiao
Tutor: ZuoJingCun
School: Beijing University of Technology
Course: Materials Science
Keywords: laser crystal BaWO4 stimulated Raman scattering Yb3+ ion spectrum
CLC: TB383.4
Type: Master's thesis
Year: 2006
Downloads: 86
Quote: 0
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Abstract


Barium tungstate crystal was recently developed as a new promising nonlinear material for crystalline nano- and picosecond Raman lasers. Doping this crystal with Yb3+ and Er3+ ions could allow it to be used as a laser active element and a nonlinear Raman medium simultaneously. In this report the single crystals of BaWO4, Yb3+, Er3+:BaWO4, and Yb3+:BaWO4 with different concentrations of K+ -codoped ions were successfully grown along c-axis direction by using the Czochralski method.Research on the process of growth and growth pattern of crystals shows that constitutional super-cooling, dislocation are the main reasons influencing the obtainment of the high qualitative BaWO4 crystals grown in the direction of <110>. The cracking of crystals due to large anisotropy in linear thermal expansion for different crystallographic directions is also an important reason, especially for the growth of crystals doped with rare earth ions. Choice of appropriate growth processing parameters could avoid the effect due to the factors mentioned above.The measurement and calculation of the sample density and X-ray powder diffraction of Yb3+:BaWO4 crystals were used to check the influence of K+ -codoped ions on the lattice structure. Influence of K+ ions on absorption and fluorescence spectra of Yb3+:BaWO4 crystals were analyzed. All these shows that a certain quantity of K+ ions doped in Yb3+:BaWO4 crystals will help to increase the quantity of Yb3+ doped ions, and improve the properties of absorption.Fluorescence spectrum of Er3+ ions in Yb3+, Er3+:BaWO4 crystals was obtained using 334nm laser as the pump light. Through analyzing and calculating absorption and fluorescence spectra, level parameters of Er3+ ions in Yb3+, Er3+:BaWO4 were obtained partly. The analysis of transition channel of Er3+ ions shows the possibility of formation of four-level structure according to the 4G9/2→4I9/2 transition at 670nm excited by short-wave laser.Spontaneous Raman spectra of BaWO4 crystal excited by 488nm argon ions laserat room temperature were obtained, and the linewidth of the Raman lines were

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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