水热法制备纳米结构铌酸锂及其光学性能研究

发布时间：2018-03-29 01:38

  本文选题：铌酸锂　切入点：纳米线　出处：《浙江大学》2010年硕士论文

【摘要】： 铌酸锂(LiNbO_3)是一种具有很高居里温度和很大自发极化强度的铁电体氧化物材料,其本身也具有良好的电光、压电和非线性光学等性能,因此在声表面波传感器、光通讯、滤波器等领域大显身手,被称为“聪明”和“通用型”晶体。铌酸锂除了不能做光源探测器以外,适合制作光的多种控制耦合和传输器件,例如:光调制、光波导、光放大、光隔离等器件。纳米线、纳米颗粒,由于量子限制效应所具有的优异的电学和光学性质,在电、光器件方面展示出诱人的前景,但是目前铌酸锂器件还停留使用体单晶、薄膜材料微电子工艺上,随着微电子向纳电子技术的发展,LiNbO_3材料也要向纳米材料制备方向发展,因此纳米结构铌酸锂的研究对我国可持续发展有重要的意义。 本文以五氧化二铌、一水氢氧化锂和氢氧化钾为原料,在自制的水热反应釜中利用水热法成功制备了多种铌酸锂微/纳米结构。 反应体系中不加入任何基底情况下,在保证三种药品的摩尔比为:Nb_2O_5:LiOH·H_2O:KOH=1:2:11条件下,改变反应物的浓度,分别制备了铌酸锂微/纳米颗粒和层状铌酸锂纳米结构;如果反应体系加入表面活性剂聚乙烯吡咯烷酮,在活性剂含量为0.04g～0.02g之间时制备出了铌酸锂纳米管阵列。 反应体系中放置多晶氧化铝基底时,我们制备了化学计量比铌酸锂微/纳米线。为了了解水热法制备铌酸锂微/纳米线的生长机理,我们分别对反应时间、反应温度、反应物浓度、衬底的作用和氢氧化钾对实验的影响等进行了深入而细致的分析,获得了优化的生长条件。最佳生长条件是:反应物Nb_2O_5、LiOH·H_2O、KOH的含量分别为0.2g、0.063g、0.464g(Nb_2O_5:LiOH·H_2O:KOH=1:2:11),反应温度为150℃,反应时间为5天。XRD、SEM和HRTEM测试表明:我们所制备的铌酸锂微/纳米线为四方形貌,长度达几十微米,生长方向为[110]。 我们对生成的铌酸锂微/纳米线进行了光波导性能研究,发现退火可以使其光波导性能非常优异。并且我们也研究了不同角度下耦合光对其性能的影响。实验中,我们发现铌酸锂对红外(1064nm),红光(650nm)和绿光(532nm)都有很好的波导性能。
[Abstract]:LiNbO3) is a kind of ferroelectric oxide material with high Curie temperature and high spontaneous polarization. It also has good electro-optic, piezoelectric and nonlinear optical properties, so it is used in surface acoustic wave sensors and optical communication. Filters and other fields are known as "smart" and "general-purpose" crystals. In addition to not being able to be light source detectors, lithium niobate is suitable for making a variety of control coupling and transmitter components for light, such as light modulation, optical waveguide, optical amplification, Optical isolation and other devices. Nanowires, nanocrystals, due to their excellent electrical and optical properties due to quantum confinement effects, have shown attractive prospects in electrical and optical devices, but at present lithium niobate devices still remain in bulk single crystals. In the microelectronic process of thin film materials, with the development of microelectronics to nano-electronic technology, LiNbO3 materials will also be developed towards nanomaterials. Therefore, the study of nanostructured lithium niobate is of great significance to the sustainable development of China. In this paper, a variety of lithium niobate microstructures / nanostructures were prepared by hydrothermal method using niobium pentoxide, lithium hydroxide monohydrate and potassium hydroxide as raw materials. Under the condition that the molar ratio of the three drugs is guaranteed to be 1: Nb2O5: LiOH H_2O:KOH=1:2:11, the lithium niobate microparticles and layered lithium niobate nanostructures are prepared by changing the concentration of the reactants without adding any substrates in the reaction system. If the surfactant polyvinylpyrrolidone is added to the reaction system, the lithium niobate nanotube array is prepared when the surfactant content is 0.04g~0.02g. In order to understand the growth mechanism of lithium niobate microwires / nanowires prepared by hydrothermal method, we prepared stoichiometric lithium niobate microwires / nanowires by placing polycrystalline alumina substrates in the reaction system. The concentration of reactants, the effect of substrate and the effect of potassium hydroxide on the experiment were analyzed in detail, and the optimized growth conditions were obtained. The optimum growth conditions were as follows: the content of Nb2O5 LiH2O5OH, LiH2OKoh, and Koh was 0.2g / t 0.063g / t 0.464g / g, respectively, and the reaction temperature was 150 鈩，

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