水热法制备一维钛酸锶钡晶体及生长机理的研究

发布时间：2018-03-27 12:13

本文选题：水热法　切入点：一维钛酸锶钡晶体　出处：《西南石油大学》2015年硕士论文

【摘要】：钛酸锶钡可以通过调节钡和锶的比例,改变居里温度(106K-393K),同时调节材料的介电性能、光学性能以及压电性能,作为功能材料广泛的应用于可调谐微波器件、移相器、红外探测、动态随机储存器等体积小而容量大的器件中。从材料的结构知道,晶体形貌对材料的性能有着重要的影响,而一维材料在一维方向上具有优异的物理化学性能,因此一维材料的制备引起广泛的关注。本文用钛酸丁酯、乙酸锶和乙酸钡为基本原料,采用溶胶-凝胶法,通过控制抑制剂乙二醇甲醚的浓度制备出非晶态的凝胶和含有锐钛矿TiO2晶相的凝胶,将两种凝胶作为水热前驱体,在相同的水热条件下进行水热处理,水热温度为230℃,保温12h,2mol/L的KOH作为矿化剂,填充度为85%,利用FTIR、XRD、SEM等对前驱体以及相对应的水热产物进行表征,研究了前驱体的结晶状态对水热产物的物相以及形貌的影响。实验结果：采用非晶态的凝胶作为前驱体,其水热产物是钛酸锶钡纳米粉体颗粒,采用含有锐钛矿Ti02晶相的凝胶作为前驱体,其水热产物是钛酸锶钡纳米粉体颗粒和一维钛酸锶钡晶体,其中一维钛酸锶钡晶体长度为40um～200um,直径在1um左右,并且被大量粉体包覆着。用浓度为0.1%的六偏磷酸钠、pH值为10左右的溶液作为分散剂,将水热产物加入分散剂后,超声波震荡15min,再将混合溶液用600目筛网过滤,这样对粉体与一维晶体进行分离。将钛酸丁酯、乙酸锶和乙酸钡加入到过量的去离子水中,生成共沉淀物,另一种共沉淀物是将钛酸丁酯加入去离子水中后,通过水浴加热使溶液成溶胶,然后加入乙酸锶和乙酸钡形成共沉淀物,利用XRD对两种共沉淀物进行物相检测,结果表明两种沉淀物中都具有多种晶相,其中第一种沉淀物中含有锐钛矿TiO2晶相,而第二种沉淀物中不含有锐钛矿TiO2晶相。将两种沉淀物作为前驱体,在相同的条件下进行水热处理,利用XRD、SEM对水热产物进行表征,结果显示含有锐钛矿TiO2晶相的沉淀物前驱体的水热产物是一维钛酸锶钡晶体和纳米粉体颗粒的混合物,另一种沉淀物前驱体的水热产物是单一的钛酸锶钡纳米粉体颗粒。对第一种沉淀物前驱体进行不同时间的水热处理,观察一维钛酸锶钡晶体的生长过程并对其水热生长机理进行初探。将纳米锐钛矿TiO2晶体与非晶态凝胶混合作为前驱体,然后进行水热处理,水热产物是钛酸锶钡纳米粉体颗粒和一维晶体的混合物；将纳米锐钛矿TiO2晶体与不含有锐钛矿TiO2晶相的共沉淀物混合作为前驱体,然后进行水热处理,水热产物是钛酸锶钡纳米粉体颗粒和一维晶体的混合物。用高倍透射显微镜以及电子衍射对一维钛酸锶钡晶体进行表征,结果显示,一维钛酸锶钡晶体呈单晶态,生长晶面为(001),一维钛酸锶钡晶体与锐钛矿TiO2共格生长。为了使水热产物中的一维钛酸锶钡晶体和粉末完全分离,采用两步水热法制备一维钛酸锶钡晶体。第一步水热时根据所查的文献制备出一维的锐钛矿TiO2,然后再将一维的锐钛矿TiO2与过量的乙酸锶和乙酸钡混合作为水热前驱体,再进行第二次水热反应,得到一维的钛酸锶钡晶体、碳酸锶和碳酸锶钡粉末颗粒混合物,将水热产物经过酸洗,便能去掉粉体而留下一维钛酸锶钡晶体。
[Abstract]:Barium strontium titanate can be adjusted by the ratio of barium and strontium, change the Curie temperature (106K-393K), while adjusting the dielectric properties of materials, optical properties and piezoelectric properties, application as functional materials in a wide range of tunable microwave devices, phase shifter, infrared detection, dynamic random memory such as small volume and large capacity of devices know. From the material structure, has an important effect on crystal morphology of the material properties, and one-dimensional materials have excellent physical and chemical properties in one direction, so one-dimensional material preparation has attracted much attention.
In this paper, using tetrabutyl titanate, barium strontium acetate and acetic acid as raw materials by the sol-gel method, the concentration of inhibitors of ethylene glycol monomethyl ether was prepared by gel gel containing amorphous and anatase TiO2 crystal phase, two gel as hydrothermal precursor by hydrothermal treatment under hydrothermal conditions are the same under the hot water temperature is 230 DEG C, holding 12h, 2mol/L KOH as mineralizer, filling degree is 85%, the use of FTIR, XRD, the precursor and the hydrothermal products corresponding to SEM were characterized. The crystalline state of the precursor of hydrothermal products to study the phase and morphology of the impact experiments. Results: using amorphous gel as precursor, the hydrothermal products are barium strontium titanate nano powder particle, the anatase crystalline phase containing Ti02 gel as precursor, the hydrothermal products are barium strontium titanate nano powder particle and one-dimensional barium strontium titanate crystal, which One dimensional barium strontium titanate crystal length is 40um ~ 200um, 1um in diameter, and a powder coated with a concentration of 0.1%. Six sodium phosphate solution, pH value is about 10 as dispersant, the hydrothermal products after adding dispersant, ultrasonic 15min, and then the mixed solution with 600 mesh sieve, so the powder and one-dimensional crystal separation.
The tetrabutyl titanate, barium strontium acetate and acetic acid into deionized water to excess, generating a total sediment, another is the coprecipitate of butyl titanate into deionized water, with water bath heating the solution sol, then adding barium strontium acetate and acetic acid to form precipitates, two co precipitate phase detection using XRD and the results show that two kinds of sediments have a variety of crystal phase, wherein the first precipitate containing anatase TiO2 crystal phase, while the second sediments do not contain anatase TiO2 crystal. The two kinds of precipitates as precursor, hydrothermal treatment, in the same conditions by using XRD, SEM on hydrothermal products the characterization results show, hydrothermal products precipitate precursor containing TiO2 anatase crystalline phase is a mixture of one-dimensional strontium barium titanate crystal and nano powder particles, another precipitate precursor hydrothermal products is single A barium strontium titanate nanopowder was prepared. Hydrothermal treatment of the precursor of the first precipitate at different time was carried out to observe the growth process of one-dimensional strontium barium titanate crystal and its hydrothermal growth mechanism.
The nano anatase TiO2 crystal mixed with amorphous gel as precursor, followed by hydrothermal treatment, the hydrothermal product is a mixture of barium strontium titanate nano powder particles and one-dimensional crystals; nano anatase TiO2 crystal mixed with anatase crystalline phase does not contain TiO2 precipitates as precursor, followed by hydrothermal treatment the hydrothermal product is a mixture of barium strontium titanate nano powder particle and one-dimensional crystal. The one-dimensional barium strontium titanate crystals were characterized by high-resolution transmission microscopy and electron diffraction showed that one-dimensional barium strontium titanate crystals are single crystalline, the growth of crystal plane (001), barium strontium titanate and anatase crystal one-dimensional TiO2 lattice growth.
In order to make the hydrothermal products in one-dimensional strontium barium titanate crystal and powder separation to prepare one-dimensional barium strontium titanate crystal by two step hydrothermal method. The first step is to check the hot water document prepared anatase TiO2 one-dimensional, then the one-dimensional anatase TiO2 with excess acetic acid and acetic acid mixed barium strontium as the hydrothermal precursor, then second hydrothermal reaction by barium strontium titanate crystal one-dimensional, strontium carbonate and strontium barium carbonate powder mixture, the hydrothermal products after pickling, can remove the powder and leave one-dimensional barium strontium titanate crystal.

【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.35;O78

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