锆钛酸钡钙的结构与铁电光学性能研究

通过溶胶凝胶法,在Pt/TiO2/SiO2/Si衬底和ITO导电玻璃衬底上分别制备了BaTiO3(BTO)、(Ba0.85Ca0.15)TiO3(BCT)、Ba(Ti0.8Zr0.2)O3(BZT)和(Ba0.85Ca0.15)(Ti0.8Zr0.2)O3(BCZT)薄膜.X射线衍射结果表示,Ca、Zr元素成功掺入钛酸钡薄膜,并且造成了衍射峰的移动,对薄膜的铁电性能有较大的提升.同时用积分球光谱仪测试了薄膜的吸收光谱,通过计算得到薄膜的禁带宽度.结果 表明锆钛酸钡钙薄膜具有较小的光学带隙为3.1 eV.     

超细钛酸钡粉体湿化学合成技术

近十年来，钛酸钡粉体的合成技术发展十分迅速。其中，超细钛酸钡粉体的湿化学合成技术倍受关注，主要包括溶胶-凝胶、溶胶-沉淀、燃烧合成、化学共沉淀和水热合成等多种方法。简要综述了这5种主要的湿化学合成工艺，并重点分析了溶胶-凝胶法等制备钛酸钡粉体过程中各种因素对粉体的粒径和形态的影响。     

溶胶-凝胶法制备钛酸钡纳米粉体

以钛酸四丁酯和乙酸钡为原料,乙醇和乙酸为溶剂,采用溶胶-凝胶法制备了钛酸钡纳米粉体,并通过XRD、SEM、TG-DTA分析,确定最优工艺条件为：凝胶化温度70℃,混合溶液p H值为3.0～4.0,热处理温度800℃,可获得粒径在50 nm左右的单一钙钛矿相钛酸钡粉体。     

溶胶-凝胶法低温合成钛酸钡纳米晶粉体

采用金属钡与乙二醇甲醚反应,形成乙二醇甲氧钡,再与钛酸四丁酯按照钡钛比为1：1的摩尔比配料混合后在130℃回流1h,获得钡钛复合醇盐．然后加入一定量的去离子水,溶液迅速成胶,将湿凝胶陈化干燥～热处理．成功合成了钛酸钡纳米晶粉体,合成温度低于150℃：且不同的加水量不仅影响凝胶的外观．同样对凝胶的析晶温度和晶体的种类有着重要的影响,当水与溶胶中钡离子的摩尔比为xw≥3时．均可得到纯净的钛酸钡纳米晶粉体。     

Sol-Gel技术制备锆溶胶的研究

以廉价无机盐氧氯化锆（ZrOCl·28H2O）为起始原料,采用溶胶-凝胶（Sol-Gel）技术合成出锆溶胶,并探讨了制备过程中各种因素对锆溶胶性质的影响。     

醇盐锆水解制备ZrO2粉体的研究

选用实验室合成的醇盐锆为前驱体，采用ｓｏｌ－ｇｅｌ工艺制备了氧化锆粉体。利用ＴＥＤ、ＤＴＡ、ＸＲＤ、ＩＲ光谱等手段研究了水解过程及水解产物的热处理过程，若适当控制醇盐锆水解条件，可制成亚微米级分布均匀的超细粉体。     

纳米钛酸钡电子陶瓷粉体的制备技术

本文介绍了功能介电材料BaTiO3粉体主要制备技术及最新进展，讨论了这些技术的优缺点和对介电材料发展的影响，指出液相化学合成法是现阶段制备BaTiO3的主要方法，而作为液相法之一的直接沉淀法由于具有设备简单，操作方便，粉体粒径小，颗粒分布等优点有着诱人的工业应用前景。     

超细硼化锆粉体制备过程中的影响因素探究

探究了溶胶-凝胶协同碳热还原反应制备超细ZrB2粉体中Zr4+与柠檬酸的配比r、溶胶-凝胶温度T、体系pH值和分散剂含量c对ZrB2前驱体及热解产物的影响.并采用X射线衍射仪、红外光谱仪、激光粒度仪、场发射扫描电镜和透射电镜对ZrB2前驱体及热解产物进行表征和分析.结果表明:r=2,pH=4为柠檬酸和Zr4+发生络合反应的最佳条件;当T=50℃时,产物基本为球形或类球形,且粒度分布均匀;聚乙二醇除分散作用外,还能够对溶胶中团簇的交联起到“导向”作用,使热解后的晶粒排列有序,当c=2％时,可获得分散性好、尺寸均匀的产物.     

溶胶-凝胶法制备纳米硼化锆粉体的研究

笔者以H₃BO₃为硼源,葡萄糖为碳源,草酸为成胶剂,采用溶胶-凝胶法,通过ZrOCl₂溶液制备硼化锆前驱体。采用还原反应法,分别在气氛炉中和微波炉中合成硼化锆,探讨不同温度和时间对合成粉体的影响,用XRD、SEM和EDS等分析方法对粉体进行了表征。实验结果表明,在气氛炉烧结过程中,当反应原料中Zr、B、C元素的比例为1∶4∶25时可得到高纯度和纳米级的硼化锆。在微波加热合成ZrB₂粉体的过程中,通过不同功率和烧结时间,在埋碳粉和微波介质的作用下进行,但未得到理想的ZrB₂粉体,其原因可能是烧结温度未达到ZrB₂合成的反应温度或是ZrB₂在烧结的过程中被氧化。     

BaTiO_3超细粉体的制备研究进展

综述了BaTiO3的研究进展,从BaTiO3的介电常数和化学掺杂出发,重点介绍了目前国内外BaTiO3的制备方法及其特点,最后展望了BaTiO3的发展趋势。     

纳米钛酸钡制备方法的最新进展

本文介绍了钛酸钡粉体主要制备技术及最新进展.指出基于制备方法的改进和研究手段的拓宽和深入,材料科学、物理学和化学工程等多学科的密切合作,纳米钛酸钡的制备方法也迈入了新的阶段.     

Long term stability of electrocaloric response in barium zirconate titanate

The stability of the electrocaloric effect under electric field cycling is an important consideration in the development of solid-state cooling devices. Here we report measurements carried out on Ba(Zr_0.2Ti_0.8)O₃ ceramics which reveal that the adiabatic temperature change, polarization-electric field hysteresis loops and dielectric permittivity/loss show stable behavior up to 10⁵ cycles. We further demonstrate that the loss in electrocaloric response observed after 10⁵ cycles is associated with the migration of oxygen vacancies. As a result, the electrical properties of the material are changed leading to an increase in leakage current and Joule heating. Reversing the polarity of the electric field after every 10⁵ cycles changes the migration direction of oxygen vacancies, thereby preventing charge accumulation at grain boundaries and electrodes. By doing so, the electrocaloric stability is improved and the adiabatic temperature remains constant even after 10⁶ cycles, much higher than achieved in commercially available barium titanate ceramics.     

New synthesis route for lead zirconate titanate powder

Phase pure lead zirconate titanate (PZT) powder was produced via a new aqueous coprecipitation method. A suite of characterization techniques, including FTIR, Raman, X-ray diffraction, SEM as well as nitrogen sorption were employed to investigate the structural evolution of the synthesized and calcined powder. The dried precipitate formed in aqueous phase yielded approximately 80 wt% final product after calcination. The PZT perovskite structure was obtained after calcination at 550 °C for 3 h. Milling of the calcined powder reduced the mean particle size from approximately 10 µm to 2 µm. With increasing calcination temperature from 550 °C to 700 °C, both surface area and pore volume decreased while pore size increased from 3.4 nm to 9.8 nm. The bulk density of pelletized samples increased from 4.83 to 7.57 g/cm³ with increasing sintering temperature from 800 °C to 1200 °C. Powder processing using this aqueous route is simple and reproducible leading to a method that is readily scalable for industrial applications.     

一种钛酸钡制备方法实验研究

以硫酸法钛白生产过程中的中间产品工业钛液（TiOSO4）为钛源,通过常温水解获得正钛酸,经草酸溶解获得草酸氧钛酸,再与氯化钡共沉淀得到草酸氧钛酸钡,高温煅烧后制备得到电子级钛酸钡产品。实验确定最佳制备条件：钛液水解pH为2.5～3.5,草酸氧钛酸生成温度和草酸氧钛酸钡共沉淀温度均选择50～70 ℃,共沉淀pH为2.5,煅烧温度为800 ℃,煅烧时间为2 h。分析结果表明,以工业钛液为钛源生产钛酸钡的成本明显低于偏钛酸。     

Influence of Cd doping on the electro-strain of barium zirconate titanate ceramics

Cadmium doped barium zirconate titanate (Ba_1−xCd_x)(Zr_0.13Ti_0.87)O₃ (BCDZT) ferroelectric ceramic compositions with x=0, 0.02, 0.04 and 0.06 have been prepared by solid state reaction method. X-ray diffraction studies reveal a pseudocubic structure. For increasing Cd content, the bulk ceramic micro-structure reveals an increasing grain size and density. Variations in the dielectric, piezoelectric and unipolar electric field induced strain characteristics are discussed. Increasing Cd content reduces the coercive field, increases the remnant polarization and does not affect the ferroelectric-paraelectric phase transition temperature (~60 °C). An optimum Cd content x=0.06 produces highly resistive ceramics with low dielectric loss (tanδ=0.019), and a maximum value of piezoelectric charge constant d₃₃=114 pC/N and unipolar electro-strain of ~0.07%.     

锆钛酸铅陶瓷的烧结研究进展

综述了国内外锆钛酸铅(PZT)压电陶瓷的烧结研究进展，介绍了各国研究者为获得烧结致密、性能优良的PZT陶瓷所采取的各种措施，并展望了其发展方向。     

Low-temperature preparation of hydrothermal lead zirconate titanate thin films

In preparing lead zirconate titanate thin films under hydrothermal conditions, we investigated the effects of concentrations of nutrient and mineralizer, reaction time and reaction temperature on crystallinity, grain size and shape. Experiments were performed in the ranges of 0.1-1.0M Pb(NO₃)₂, and 0-6.0M KOH with varying reaction time from 0 to 48 hours at 60-200 °C. In the experiment, lead zirconate titanate thin film of homogeneous crystalline grain was obtained through a 24 hour reaction with 0.4M Pb(NO₃)₂ and 5.0M KOH at 140 °C. The thickness of the film was 0.9-1.6 μm, and it exhibited a saturation polarization (Ps) of 18.3 μC/cm², remnant polarization (Pr) of 7.4 μC/ cm₂ and coercive field (Ec) of 0.41 kV/cm. The dielectric constant and loss (δ) measured at 1 kHz were approximately 1020 and 0.15, respectively.     

Identification of quality parameters for barium titanate powder

The authors describe the results of developing methods for determining some quality parameters of barium titanate powder, which is the main component in some ceramics that are used to produce capacitors. The degree of transformation of ZnO and BaTiO₃, the volume density of sintered powder, the degree of its dissolution in hydrochloric acid, and some diffraction characteristics of BaTiO₃ powders are determined according to the developed methods and can predict with a sufficient degree of reliability the quality of ceramic capacitors made from barium titanate powders.     

Polyvinylpyrrolidone modified barium zirconate titanate /polyvinylidene fluoride nanocomposites as self-powered sensor

Highly flexible biocompatible nanocomposites comprising of Polyvinylpyrrolidone (PVP) modified Barium Calcium Zirconate Titanate (BCT-BZT) /Polyvinylidene fluoride (PVDF) were fabricated. The crystalline BCT-BZT powders were synthesized by a simple sol-gel method. Rietveld refinement analysis confirmed the coexistence of orthorhombic and tetragonal phase in the synthesized powders. The structural, dielectric and ferroelectric properties of the composites were analysed. Addition of PVP modified BCT-BZT powders was observed to enhance the polar phase in PVDF matrix. The piezoelectric output response as a function of different weight percentage of ceramic powders in the PVDF matrix was investigated. The optimal device with 60?wt% PVP modified BCT-BZT powders exhibited maximum peak to peak voltage of 23?V when tested for harnessing waste biomechanical energy (human hand palm force). The nanogenerator was easily scaled up to 4?×?4?cm and the stored power was utilized for powering fifty five LEDs. The fabricated device is flexible, light- weight and eco-friendly. Therefore, it can be explored as a potential candidate for application as self powered sensor.