表面活性剂对溶胶-凝胶法制备Ba0.6Sr0.4TiO3粉体的影响

钛酸锶钡(BST)陶瓷是一种性能优异的电容器材料、热敏材料和铁电压电材料,具有非常广阔的应用领域.采用溶胶-凝胶法合成了Ba0.6Sr0.4TiO3纳米粉体,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、激光粒度分析仪对粉体的物相组成、颗粒大小和形态进行了分析,利用红外光谱仪(FT-IR)研究了表面活性剂在合成纳米Ba0.6Sr0.4TiO3过程中的作用,并重点考察了表面活性剂对Ba0.6Sr0.4TiO3粉体性能的影响.研究结果表明,通过添加适量的表面活性剂能有效改善纳米钛酸锶钡粉体的表面性能,使纳米钛酸锶钡具有较好的分散性,可充分发挥材料的纳米效应.     

液相法制备氧化锌纳米粉体的研究进展

液相法是制备性能良好的氧化锌粉体的有效方法,因其制备形式的多样性、工艺简单、产物组成易控等特点而得到广泛应用.概述了液相法合成纳米ZnO粉体的研究进展,重点介绍了几种基本的液相合成法,如沉淀法、溶胶-凝胶法、水热法、微乳液法、超重力法,比较其优缺点,并对进一步的研究方向和发展趋势提出了见解.     

BST铁电薄膜材料的研究现状及其进展

铁电钛酸锶钡(BaxSr1-x)TiO3是一种具有十分优越铁电/介电性能的材料,在可调微波器件及动态随机存储器件方面有很好的应用前景.介绍了钛酸锶钡薄膜材料的基本结构、制备技术、掺杂改性等方面的研究现状,并在性能改善的基础上,指出了该材料的未来发展方向.     

镧掺杂Sr0.4Ba0.6TiO3材料的导热性能

研究了不同镧掺杂浓度下Sr0.4Ba0.6TiO3材料的导热性能,研究镧元素对其导热性能的影响,得到了不同掺杂量下钛酸锶钡材料的热导率,材料密度随烧结温度与成型压力的增加而增大;同时发现少量镧元素的掺杂,可以增加钛酸锶钡材料的热导率;当镧元素掺杂量较大时,降低了材料的热导率.钛酸锶钡材料的电子热导率随材料烧结温度的升高基本不变,声子热导率随材料烧结温度的升高而增加.     

纳米晶钛酸锶钡(Ba0.5Sr0.5TiO3)粉体的微波水热合成

采用微波水热法合成了纳米晶钛酸锶钡(Ba0.5Sr0.5TiO3)粉体,通过XRD、TEM、SEM等分析手段表征粉体,研究了微波水热合成反应温度、时间和前驱物浓度对反应产物形貌、粒度的影响,获得了制备纳米晶钛酸锶钡粉体的最优工艺参数.实验结果表明:在微波水热反应温度为195℃、反应时间20～30min、前驱物浓度为0.16mol/L时获得的粉体粒径小而且均匀,粉体平均粒度为60nm.     

钛酸锶钡纳米粒子的低温煅烧法制备与表征

以氢氧化钡、氢氧化锶和钛酸丁酯为原料,采用低温煅烧(300～500℃)法合成了钛酸锶钡(BST)纳米粒子.用XRD、SEM、TEM和IR对产品进行了表征;用TG-DTA对前驱物的热演化过程进行了分析.结果表明,所得钛酸锶钡纳米粒子大小分布均匀,粒径约为13～20nm,粒子形状近似为球形,晶相结构为立方相.该粉体为完全互溶体的固溶体,随Sr含量的增加,晶胞参数a和晶胞体积V减小,a随组成呈线性关系,符合Vegard定律.     

退火工艺对钛酸锶钡铁电多层膜结构与物性的影响

立足于无铅型钛酸锶钡(BST)铁电多层膜的制备及物性研究.采用溶胶-凝胶方法制备了Ba0.9Sr0.1TiO3铁电多层膜,并利用快速退火炉对多层膜进行热处理.重点分析两种不同热处理工艺对钛酸锶钡多层膜微观结构及相关物理性能的影响.通过X射线衍射(XRD),扫描隧道显微镜(SEM)及可见光范围反射谱测量等的表征方法,研究钛酸锶钡铁电多层膜微观结构的演化和形成机理,为制备性能优良的钛酸锶钡铁电多层膜提供基础数据.     

钛酸锶钡(BST)薄膜晶化过程研究

采用射频磁控溅RF-magnetron sputting)法制备了钛酸锶钡(BST)薄膜,用快速热处理(RTA)和常缮规热处理(CFA)对薄膜进行晶化.利用AFM、XRD等技术分析了钛酸锶钡薄膜的晶化过程,以及不同退火温度和退火方法下薄膜的晶粒、晶相特性.实验表明:钛酸锶钡薄膜在500℃开始结晶,到700℃左右时结晶比较完善,晶化过程中没有出现择优取向;从表面形貌和X射线衍射图综合分析,快速退火的晶化效果要优于常规退火.     

应用于DRAMs的钛酸锶钡薄膜的研究进展

随着DRAMs存储密度的增加,传统材料已不再适用于将来的DRAMs技术的发展.在目前研究的新型替代材料中,钛酸锶钡以其优越的介电性能越来越引起人们的关注.介绍了随DRAMs的发展趋势,钛酸锶钡薄膜的研究进展,包括其制备方法、研究状况及影响其介电性能的因素,并提出了下一步研究工作中需要解决的几个问题.     

Glycothermal法制备钛酸锶钡纳米晶的研究

采用Glycothermal法制备了尺寸分布窄的准球形钛酸锶钡纳米晶. 利用XRD、拉曼光谱以及TEM对合成纳米晶结构及形貌进行了测定与表征, 研究了Glycothermal法制备BST纳米晶过程中醇-水比、温度和液相中Ba/Sr比等因素对产物组成、晶体结构、晶粒尺寸与结晶性的影响规律. 结果表明: 利用Glycothermal法, 可在无矿化剂的条件下制备出单分散性好的BST纳米晶.     

火焰原子吸收光谱法测定光学新材料钛酸钡锶中钡和锶

本文介绍了火焰原子吸收光谱法测定光学新材料钛酸钡锶中钡和锶,研究样品制备、测试条件和共存元素干扰消除。本法的准确度和精密度均达到满意的结果。     

Hydro(Solvo) Thermal Synthesis and Characterization of Bax Sr1-x TiO3 Nanopowders

Nano-sized barium strontium titanate (BaxSr1-x TiO3, BST) powders were synthesized with hydrothermal and solvothermal methods at 120 ℃ for 4 h based on the reaction precursor of barium acetate, strontium acetate, tetrabutyl titanium and (CH3 )4NOH. The crystalline phase, particle size and morphology of the BST powders were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Influences of reaction temperature and reaction time on the morphologies of powders were also discussed.     

原子吸收光谱法测定光学新材料钛酸钡锶中锶的研究

本文介绍火焰原子吸收光谱法测定光学新材料钛酸钡锶中锶的方法,研究样品制备和测试条件,消除共存元素干扰。本法的回收率为99～101％,相对标准偏差为0.72％。     

钛酸钡的制备研究进展

对钛酸钡粉末的制备方法进行了综合。传统的高温固相合成法已不能满足电子技术微型化和集成化发展对钛酸钡粉体提出的超细、高纯、单分散要求。从制备成本和操作过程来看，经过改进的共沉淀法、草酸盐法和水热法是制备高纯、亚微米级钛酸钡粉末的重要方法，在大规模生产中有较好的应用前景。在水热过程中，通过选择适当的钛源和水热条件，可以制备出高纯、单分散的亚微米级及纳米级钛酸钡粉体。低温直接合成法因其原料易得，过程简单，是一种在大规模生产上较有应用前景的制备纳米钛酸钡的方法。     

Properties of BaxSr1−x TiO3 films grown by rf magnetron sputtering on sapphire with an SrTiO3 sublayer

Results are presented of experiments to deposit barium strontium titanate films on an r-cut sapphire substrate with a strontium titanate sublayer. It is shown that the use of a strontium titanate sublayer can ensure that the dielectric properties of barium strontium titanate films have a weak temperature dependence over a wide temperature range. Moreover, the parameters of the films are consistent with those required to fabricate microwave microelectronics devices. Pis’ma Zh. Tekh. Fiz. 25, 1–5 (July 26, 1999)     

火焰发射光谱法测定光学材料钛酸钡锶中钡的研究

本文介绍了火焰发射光谱法测定光学材料钛酸钡锶中钡的方法,包括样品制备、测试条件、干扰试验及消除共存元素的干扰等。实验证明本方法准确、可靠。     

Synthesis and characterization of nanocrystalline barium strontium titanate powders prepared by citrate precursor method

Nanocrystalline and well dispersed barium strontium titanate (BST) powders were prepared by a novel and simple citrate precursor method. This method involved direct crystallization of a white precursor from a stable solution in the citric acid (CA)–ethylene glycol (EG)–tetrabutyl titanate–M²⁺ (M = Ba, Sr) system under a specific pH value range. Subsequent heat treatment of the precursor at 850 °C led to a pure phase BST powder. TG/DTA was used to examine the decomposition behaviour of the precursor. The crystalline phase and morphology of the BST powders were investigated by XRD and TEM. It was found that the BST powders synthesized by citrate precursor process were more homogeneous and uniform than that obtained by the citrate gel method.     

Electrical characterization of BaTiO3 made by hydrothermal methods

The manufacture of multilayer capacitors based on barium titanate requires improved precursor powders. In this paper the dielectric properties of barium titanate ceramics made from hydrothermally precipitated material are compared with those powders obtained commercially and prepared by calcination. The greater porosity of hydrothermal powders tends to reduce their effective dielectric constant but preheating them to 950 C before sintering produced high density ceramic with higher values of _r. The dielectric losses of these materials are higher than those produced by traditional methods. Their low Curie temperatures (106–8 C) are related to the high strontium concentration (4.7 mol%) present in the starting materials. The grain sizes of these ceramics are less sensitive to sintering temperature than those made using calcined powders, with no anomalous grain growth.     

Energy storage in ceramic dielectrics

An evaluation has been made of the energy storage capabilities of ceramic dielectrics that were considered likely to provide high energy/volume efficiency on the basis of their expected permittivity-field characteristics. Data for fields up to 400 kV/cm are presented for a strontium titanate, and for a barium titanate ceramic. The materials were in thick-film form and bonded with a small amount of glass. At the maximum fields, energy storage in the barium titanate ceramic was close to that reported earlier for glass-bonded lead zirconate (approx. 2.0 J/cm³), but was about 30% lower in the strontium titanate material.     

Fabrication of green films of single- and multi-component ceramic composites by electrophoretic deposition technique

An electrophoretic technique for the formation of ceramic composites is demonstrated in the systems of biomedical hydroxyapatite–yttria-stabilized zirconia and ferroelectric barium titanate–strontium titanate. Ceramic powders show different behaviour depending on the nature of the solvent media chosen. For such purposes, a solvent mixture of acetylacetone and alcohols proved effective for adjusting the composition of deposited films. This revised version was published online in November 2006 with corrections to the Cover Date.