摘要：铌酸锂晶体（LiNbO3，简写LN）是一种集多种功能、多种用途于一身的人造晶体，但光损伤限制了其应用范围。掺杂超过阈值浓度的镁离子，能够有效抑制光损伤，但生长大尺寸、高均匀性掺镁铌酸锂晶体的难度很大，并且尚未见关于利用坩埚下降法生长高掺镁铌酸锂晶体的报道。74086

本论文将以大尺寸、镁掺杂量达到5mol%的铌酸锂晶体为研究对象，采用坩埚下降法生长了直径为2英寸的LN：5Mg晶体。LN: 5Mg多晶料XRD结果表明镁的掺入并没有改变铌酸锂的晶体结构。LN: 5Mg晶体的X射线双摇摆曲线测试结果显示峰的半高宽是16″，峰貌尖锐、对称、没有出现劈裂现象，表明晶体具有良好的结晶型，并且内部的应力较小。LN: 5Mg晶体的紫外吸收边均在314。3nm附近，相对于纯LN的紫外吸收边蓝移了4。5nm，表明镁离子有效地掺入；但LN: 5Mg晶体不同测试点的OH-峰均出现在3482。86cm-1，这意味着晶体中掺入的镁离子未达到阈值浓度，而且半峰宽、形状、位置一致也表明晶体成分均匀性有待提高。光斑畸变结果表明LN：5Mg晶体的抗光损伤能力达到103mW/cm2，只比纯LN晶体提高了2个数量级，而比提拉法生长的LN:5Mg晶体阈值浓度低了2个量级，表明实际掺入Mg离子的量未达到超过阈值浓度，还需要进一步优化坩埚下降法的生长工艺，提高大尺寸、高掺镁LN晶体的质量。

毕业论文关键词: 坩埚下降法；高掺镁；铌酸锂晶体；大尺寸 

Study on the growth and optical properties of large size Mg-doped LiNbO3 niobate

Abstract：Lithium niobate (LiNbO3, abbreviated LN) is an artificial crystal combines variety functions and variety usage, but the optical damage limits its scope of application。 Doping with magnesium ions exceeding the threshold concentration can effectively inhibit optical damage, but it is difficult to grow magnesium-doped lithium niobate crystals with large size and high homogeneity。 Up to now, there are rare reports about growing heavily Mg-doped lithium niobate crystals by Bridgeman method。

In this paper, LN: 5Mg crystal with diameter of 2 inches was grown by Bridgeman method。 The XRD result of LN: 5Mg polycrystal showed that the incorporation of magnesium did not change the crystal structure of lithium niobate。 The result of X-ray double-rock curve showed that full width at half maximum was 16 ", and the peak was sharp, symmetrical, without splitting, which indicated that the crystal possessed good crystallization performance and small thermal stress。 The UV absorption edge was at about 314。3nm and blue shifted 4。5nm compared to CLN crystal。 However, the OH- absorption peaks at different test points of LN: Mg5 crystal appeared at 3482。86cm-1, which meant that the incorporation of magnesium ions in the crystal does not exceed the threshold concentration。 Besides, the half-width width, shape and position exhibited the composition uniformity needs to be improved。 The optical damage resistance of LN: 5Mg crystal was measured as 103W/cm2, which is 2 orders of magnitude higher than that of pure LN crystal, and 2 orders of magnitude higher than LN: 5Mg crystal grown by Czochralski method, which revealed that the concentration of Mg ions actually did no exceed the threshold concentration。 Thus, the growing process of Bridgeman method should be further optimized to improve the quality of large size heavily Mg-doped LN crystal。

KeyWords： Bridgeman method; heavily Mg-doped; LiNbO3 niobate; large size

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目 录

1。 绪论 1

1。1 铌酸锂晶体及其缺陷结构 1

1。1。1 铌酸锂晶体的晶格结构及其基本物理性质