【作者】 李月宝；

【导师】 潘建国；

【作者基本信息】 宁波大学 ， 物理化学， 2010， 硕士

【摘要】 非线性光学晶体材料的研究一直备受材料学者的关注,近年来,钒酸盐非线性光学晶体的研究开始引起人们的注意。由于具有高价态的d0电子组态的过渡金属离子易受二阶Jahn-Teller效应影响,在含有MO6n-离子的理想的八面体配位场中,HOMO和HOLO轨道杂化将会使HOMO能级下降,体系更加稳定,它驱使MO₆^n-基团沿着正八面体的二次、三次或四次轴方向发生畸变,从而形成不对称的结构,有利于形成非中心对称结构的晶体。钒极易与氧结合形成钒氧多面体且易发生畸变,因此钒作为二阶非线性晶体材料中重要的元素应受到广泛的关注。红外非线性光学晶体K₃V₅O₁4的结构早已经见诸报道,但是最近几年才有学者对其性质进行陆续的研究。本论文利用坩埚下降法对其进行了生长实验,通过高温固相法和液相法分别对多晶原料进行了合成。经过X-射线粉末衍射图证实,高温固相法合成原料纯度比较高,可用于K₃V₅O₁4的生长。生长得到的晶体为多晶棒,但是里面包含质量比较好的片状单晶,可以作为下次生长的籽晶。对所得晶体的光、热、倍频等性质进行了测定,结果表明:K₃V₅O₁4在1000-4000 cm^-1透过率高达85%;采用TG-DTA测定其熔点为413℃;激光倍频实验得出K₃V₅O₁4晶体的倍频系数为KDP的3.7倍,是一种比较好的二阶非线性光学晶体。并且对晶体的成分进行了深入的分析。利用Rb₂CO₃与V₂O₅,通过高温固相反应得到了一种与K₃V₅O₁4异质同晶的化合物Rb₃V₅O₁4。Rb₃V₅O₁4属于三斜晶系,P31m空间群,晶胞参数为:由V50143-结构单元形成了二维层状结构,Rb⁺填充在层与层之间。通过X-射线粉末衍射图谱证实合成所得产物为Rb₃V₅O₁4纯相。Rb₃V₅O₁4具有非中心对称的晶体结构,经过粉末倍频测试,非线性光学系数约为KDP的4.2倍;在1100-4000 cm^-1的透过率高达80%以上;熔点为398℃。利用C_s2CO₃与V₂O₅,通过高温固相反应得到了一种新的的化合物CsV₂O₅。CsV₂O₅属于正交晶系,Ima2空间群,晶胞参数为:a通过磁性测试与顺磁共振测试证明了该化合物中含有一个正四价的钒原子,且V⁴⁺和V⁵⁺都与氧形成钒氧四面体结构。对所得晶体的光、热、倍频等性质进行了测定,结果表明:C_sV₂O₅在1000-7500 cm^-1透过率高达85%;其熔点为455℃;激光倍频实验得出该晶体的倍频系数为KDP的8.1倍,可以做为一种潜在的红外非线性光学晶体材料。另外,利用坩埚下降法对其进行了生长实验。更多还原

【Abstract】 In recent years, researches have been paid much attention to researches on nonlinear optical crystal materials, thus researches on nonlinear optical vanadate crystal began to attract professor’s eyes. Transition metal ions with a high-valent d0 electronic configuration was affected by second-order Jahn-Teller, in the ideal octahedral field that containing MO6n-, HOMO and HOLO changing their own orbital makes HOMO energy level lower and makes the system more stable, which makes MO6n- group along the octahedron occurs for two times, three times or even four times to form the asymmetric structure that is conducive to the formation of noncentrosymmetrical crystal structure. Vanadium can easily combine with oxygen to form vanadium-oxygen polyhedron and prone to distortion, so vanadium as important element of second-order nonlinear crystal materials should be widely concerned.It has been reported the structure of K₃V₅O₁4, a kind of infrared nonlinear optical crystal, but few scholars did research on its properties until recent years. Using the Bridgman-Stockbarger method to make a research experiment on its growth, we have succeeded in synthesizing polycrystalline materials by high-temperature solid-phase method and liquid-phase method. After X-ray powder diffraction pattern confirmed that the high-temperature solid-phase synthesis can make relatively high purity of raw materials, which can be used in growthing the K₃V₅O₁4. The crystals grow to be a multi-crystal rod, but which contains a relatively good quality single crystal flakes that can be used as the seed of growth. The obtained crystals were measured including light, heat, SHG and other properties, results showed that: K₃V₅O₁4 transmission rate is up to 85% in the 1000-4000cm-1; its melting point is 413℃determined by using TG-DTA; the second harmonic output intensity of K₃V₅O₁4 was 3.7 times as large as KDP, which is a good second-order nonlinear optical crystal. In addition, I make an in-depth analysis on the composition of the crystals.A new compound of Rb₃V₅O₁4 has been prepared by reaction of Rb2CO3 and V2O5, through the high-temperature solid-phase method, which was similar to K₃V₅O₁4. The X-ray single-crystal showed that Rb3V5014 crystallizes in a triclinic space group P31m with it can be viewed as a layered compound of V50143- unit that are capped by Rb+. By X-ray powder diffraction patterns, it is confirmed that the resultant of reaction is synthetic Rb3V5014 pure phase. Rb₃V₅O₁4 is noncentrosymmetric crystal structure, after Second harmonic generation measurements, nonlinear optical coefficient was about 4.2 times of the KDP: its transmission rate is also up to 80%; its melting point is 398℃.A new compound of C_sV₂O₅ has been prepared by reaction of Cs2CO3 and V2O5, through high-temperature solid-phase method, the resultant of reaction is a kind of new compound C_sV₂O₅. C_sV₂O₅ belongs to orthorhombic system, Ima2 space group , unit cell parameters: By paramagnetic resonance test and magnetic test, it is proved that the compound contains a series of tetravalent vanadium atoms, thus V4+and V5+are existed by combining with oxygen to form tetrahedral structure of vanadium oxide. The obtained crystals were measured including light, heat, SGH and other properties, results showed that: C_sV₂O₅ transmission rate is up to 85% in the 1000-4000 cm^-1; its melting point is 455℃determined by using TG-DTA; the second harmonic output intensity of C_sV₂O₅ was 8.1 times as large as KDP, which can serve as a potential infrared nonlinear optical crystal materials. In addition, a growth experiment of it has made by using the Bridgman-Stockbarger method.更多还原