Design of low cost gas sensor based on SrTiO3 and BaTiO3 films

We have prepared SrTiO3/BaTiO3 multilayer film on alumina substrates by a sol-gel technique and investigated their response for sensing ethanol vapor. The surface morphology of the films were characterized by atomic force microscope (AFM) showing that the grain size of the films increase up to 40 nm as the annealing temperature increased to 1000 degrees C. The ethanol sensors based on SrTiO3/BaTiO3 thin films were fabricated by applying interdigitated gold electrodes by sputtering technique. The ethanol sensing characteristics of SrTiO3/BaTiO3 thin films were quantified by the change in resistance of the sensors when they were exposed to ethanol. The optimum operating tempearature of these sensors was found to be 350 degrees C. In addition, the film annealed at 1000 degrees C exhibited p-type gas sensing behavior with the best sensitivity of 30-100 for low ethanol concentration in the range of 100-1000 ppm.     

水热法制备BaTiO3粉体

水热法制备的陶瓷粉体结晶度高，团聚少，烧结活性闹，得到了越来越广泛的重视。本文报道了水热法制备ＢａＴｉＯ３粉体的研究结果，给出ＢａＴｉＯ３粉体晶粒组成、粒度和结晶形貌与反应温度、前驱物形式以及Ｂａ、Ｔｉ摩尔比之间的关系，选择较高的反应温度，使用强碱性溶液以及较高ｍ（Ｂａ）．ｍ（Ｔｉ）比的前驱物，有利于钙钛矿型ＢａＴｉＯ３晶粒的形成。采用新制的Ｔｉ（ＯＨ）４胶体为前驱物，在Ｂａ（ＯＨ）２水溶液水热反     

Preparation of Oriented Barium Titanate Thin Films by Combination of Electrophoretic Deposition with Hydrothermal Treatment

Highly oriented barium titanate (BaTiO 3) thin films on Pt substrate were fabricated by combination of electrophoretic deposition with hydrothermal treatment.The structure and morphology of thin films were characterized by X-ray diffraction and field-emission scanning electron microscopy.It is found that the titania precursor film,Ba(OH)2 concentration and hydrothermal temperature play crucial roles in the film morphology and orientation.The BaTiO3 thin films with highly (110) preferred orientation can be f...     

四方相BaTiO3薄膜的自组装制备与表征

以(NH₄)₂TiF₆、 Ba(NO₃)₂ 和H₃BO₃为主要原料, 采用自组装单层膜(SAMs)技术, 以三氯十八烷基硅烷(octadecyl-trichloro-silane, OTS)为模版, 在玻璃基片上制备了四方相钛酸钡晶态薄膜. 改性基板的亲水性测定与原子力显微镜（AFM）测试表明, 紫外光照射使基板由疏水转变为亲水, 能够对OTS-SAM起到修饰作用. 金相显微镜观察结果显示,OTS单分子膜指导沉积的薄膜样品表面均匀, 表明OTS SAM对钛酸钡薄膜的沉积具有诱导作用; X射线衍射（XRD）与扫描电镜（SEM）表征显示, 空气中600℃下保温2h实现了薄膜由非晶态向四方相BaTiO₃晶态薄膜的转化过程, 制备的钛酸钡薄膜在基板表面呈纳米线状生长, 线长约在500～1000nm之间, 相互连接的晶粒大小约为100nm. 文章同时对自组装单层膜和钛酸钡薄膜的形成机理进行了探讨.     

PVDF/改性BaTiO3复合材料介电性能研究

用硅烷和钛酸酯偶联剂对BaTiO3粉进行了表面处理，使用溶剂法制备了PVDF／BaTiO3复合薄膜，通过疏水亲油实验定性地分析了硅烷和钛酸酯偶联剂对BaTiO3粉的偶联作用可以改善PVDF／BaTiO3的界面结合，通过测定PVDF／BaTiO3的介电常数和介电损耗角正切值表征了复合材料的介电性能，PVDF／BaTiO3扫描电子显微镜（SEM）的微观形态分析发现，经过偶联剂表面处理，BaTiO3粉在PVDF中的分散情况改善，偶联剂的用量对微观形态影响较大。     

微弧氧化法制备BaTiO3薄膜的结构特性

利用微弧氧化技术在钛衬底上制备了钛酸钡铁电薄膜.利用x射线(XRD)、扫描电镜(SEM)和能谱仪(EDS)等手段研究了电流密度和电解液浓度对微弧氧化薄膜的化学成分、相组成、结构和表面形貌的影响.结果表明,随着电流密度和电解液浓度的增加,BaTiO3的形成能力增强,薄膜的致密度下降,表面粗糙度增加;当Ba(OH)2浓度为0.2 mol/l,电流密度为5 A/cm2,微弧氧化反应18 min后,可获得具有较高简单四方结构和底心正交结构BaTiO3含量的薄膜,且薄膜与衬底具有良好的结合性能.     

High K BaTiO(3) films from metalloorganic precursors

Crack-free and dense BaTiO(3) films 4 to 8 mum thick were prepared by spinning a solution of metalloorganic precursors onto an appropriate substrate, and firing and annealing the film in air at certain temperatures to obtain appropriate grain sizes. The electrical properties of the films were studied as a function of grain size, temperature, frequency, and DC bias. Films with a grain size of 0.2 mum showed ferroelectric properties similar to bulk BaTiO(3).     

高性能BaTiO_3/PVDF介电复合材料及其薄膜电容器应用

选用柔性高分子材料聚偏氟乙烯（PVDF）作为基体,纳米钛酸钡陶瓷（BaTiO3）作为填充相,采用简单的溶液共混以及流延工艺制备BaTiO3/PVDF薄膜。通过SEM观察了复合材料体系的微观结构,研究了BaTiO3/PVDF介电复合材料的介电性能。把所制备的BaTiO3/PVDF复合材料薄膜（70mm×30mm×25μm...     

基于新型纳米复合介电材料的嵌入式微电容制备及特性

嵌入式微电容技术是一种能够使电子器件微型化,并提高其性能及可靠性的方法.研究适用于嵌入式环境的高介电材料,有着重要的意义.采用粒径为92 nm的钛酸钡（BaTiO3）颗粒作为纳米无机填充颗粒,选用聚酰亚胺（PI）作为有机基体制备新型BaTiO3/PI纳米复合薄膜,并对该薄膜的介电性能、耐压特性及温度特性进行了测试;并采用光刻、溅射、刻蚀等工艺,对BaTiO3/PI纳米复合薄膜进行图形化研究,制造嵌入式微电容器件原型,其后对该器件的介电性能进行了测试.测试结果显示,嵌入式电容器件原型的介电常数在低频下达到15以上,击穿场强达到58 MV/m以上,而刻蚀和溅射工艺对薄膜的性能影响不大.     

钛酸钡/钡铁氧体核/壳粒子的电磁性能

在以尿素为沉淀剂制备钛酸钡(BaTiO₃)/钡铁氧体(BaFe₁₂O₁₉)核/壳粒子的基础上, 采用透射电子显微镜(TEM)、X射线衍射分析仪(XRD)、傅里叶变换红外光谱仪(FT-IR)对BaTiO₃/BaFe₁₂O₁₉核/壳粒子前驱物及BaTiO₃/BaFe₁₂O₁₉核/壳粒子的形貌、结构和成份进行了表征, 采用网络矢量分析仪对BaTiO₃/BaFe₁₂O₁₉核/壳粒子的电磁特性进行了研究. 结果表明, 均匀共沉淀制得的BaTiO₃/BaFe₁₂O₁₉粒子呈现核/壳结构, BaFe₁₂O₁₉壳层对BaTiO₃的包覆均匀、完整、光滑; 在2~7GHz, BaTiO₃/BaFe₁₂O₁₉核/壳粒子的ε′和ε″分别为10.7~17.0和0.3~0.6, 均高于BaTiO₃. ε′和ε″的增大是核/壳结构所引起的界面极化加强的结果; BaTiO₃/BaFe₁₂O₁₉核/壳粒子出现了BaTiO₃所没有的磁性能, 其μ′和μ″在2~7GHz远远高于BaTiO3, 表现出了较为明显的磁损耗, 这与磁性BaFe₁₂O₁₉壳层的包覆有关.     

BaTiO3 thin film prepared by coating-pyrolysis process on Nb-doped SrTiO3 substrate

Epitaxial BaTiO3 thin film was prepared on Nb-doped SrTiO3 substrate by coating-pyrolysis process using a mixed solution of barium and titanium naphthenates. The amorphous film pyrolyzed at 470 °C was crystallized with high orientation after heat-treatment at 850 °C under low oxygen partial pressure. X-ray diffraction /2 and scans indicated that the BaTiO3 film was epitaxial relationship with Nb-doped SrTiO3 substrate. The dielectric constant was approximately 230 at 103 Hz and was monotonically decreased with increasing of frequency at room temperature.     

陶瓷片表面处理对p-PAn/n-BaTiO3复合材料性能的影响

用电化学方法在n型BaTiO3陶瓷表面进行苯胺的聚合,制备了具有p-n异质结的p-PAn/n-BaTiO3复合材料.测定了电流-电压特性曲线和压敏非线性系数α值,发现此材料具有良好的整流特性用电子扫描显微镜观察分析了聚苯胺的表面形态和异质结的界面形态.讨论了陶瓷片表面的处理对异质结性能的影响.     

Dielectric properties of Ni-coated BaTiO/sub 3-/PMMA composite

Dielectric properties of Ni-coated BaTiO(3)-PMMA (polymethyl methacrylate) composite were studied from an embedded capacitor application viewpoint. Volume loading of up to 50% was attempted, and the results were compared with uncoated BaTiO(3)-PMMA composite. Ni-coating on BaTiO(3) powder was found to greatly improve the dielectric properties of the composite, especially the dielectric constant value. K values of about 100 with temperature-stable X7E characteristics were realized.     

Fabrication of La<Subscript>3</Subscript>TaO<Subscript>7</Subscript> using a new precursor solution route by chemical solution method

La₃TaO₇ (LTO) has been fabricated using a new precursor solution route by chemical solution method. The newly developed LTO precursor solution was obtained in ambient atmosphere. A serious of studies on the properties of LTO precursor gel and its powder annealed at different temperatures were presented in order to understand the decomposition of LTO precursor gel and the growth behavior of LTO. The single phase LTO powder and LTO film on textured Ni–W substrate were obtained after annealed at 1,100° in a gas mixture of Ar-4% H₂. But it should be pointed out that LTO film was annealed by adopting a rapid elevated temperature processing (RETP) method. X-ray diffraction shows that the LTO film on Ni–W tape was highly oriented, and its out-of-plane texture is very close to that of the underlying Ni–W substrate. The SEM investigation of LTO film reveals a dense, smooth, pinhole-free and crack-free microstructure for coated buffer. These results offer the potential to use the LTO film prepared by the new precursor solution route as a buffer layer for further manufacturing other buffer layer in coated conductors.     

Y（NO3）3掺杂BaTiO3半导体材料特性研究

本文研究了以Ｙ（ＮＯ３）３作为施主掺杂元素制备的ＰＴＣＲ材料的显微结构和宏观性能。指出施主以水溶性化合物形式引入制备的ＰＴＣＲ材料，其性能明显优于常规的施主以氧化物形式引入而得到的材料的性能。     

Preparation of lead zirconate titanate thin films with a combination of self-assembly and spin-coating techniques

A low-temperature synthetic method for preparing lead zirconate titanate (PZT) perovskite film on a Pt substrate is proposed. The method consists of the self-assembly of PZT particles on a substrate and successive spin coating with a precursor of PZT. The PZT particles that had sub-micron sizes and perovskite structures were prepared by annealing amorphous PZT particles formed from a complex alkoxide precursor. The PZT particles were deposited on a Pt substrate that was surface-modified with (3-mercaptopropyl) trimethoxysilane to chemically fix the particles on the substrate. Another PZT precursor solution was used for the spin-coating on the PZT-deposited substrate, and then the spin-coated film was annealed at 350 °C to remove organic residues left in the film. The spin-coated PZT film prepared at 350 °C had a dielectric constant of 118 at a frequency of 1000 Hz.     

微弧氧化生成钛酸盐系铁电薄膜研究

为开发新的铁电薄膜制备工艺,需将Ti板微弧氧化.采用Ba(OH)2、Ba(CH3COO)2、BaCl2、Ba(OH)2+Ba(NO3)2及Pb(CH3COO)2对Ti板进行微弧氧化试验,并对生成的薄膜进行物相组成和显微形貌的分析.结果表明:Ti板在BaCl2、Pb(CH3COO)2及Ba(OH)2+Ba(NO3)2中不...     

Barium titanate thin films deposited by electrophoresis on p-Doped Si (001) substrates

Barium titanate (BaTiO3) thin films have been prepared by electrophoretic deposition on p-doped and platinum covered silicon (Si) substrates. Their structure, nanostructure and dielectric properties were characterized. The as-deposited films were polycrystalline and composed by barium titanate nanograins with an average grain size approximately 9 nm. Annealing at high temperatures promoted grain growth, so that the samples annealed at 600 degrees C presented average grain sizes approximately 24 nm. From Raman spectroscopy measurements it was found that the tetragonal (ferroelectric) BaTiO3 phase was stabilized on the films. Also, at higher annealing temperatures, cation disorder was reduced on the films. From measurements of the temperature dependence of the dielectric permittivity the corresponding paraelectric-ferroelectric phase transition was determined. The observed transition temperature (approximately 100 degrees C) was found to be below the BaTiO3 bulk or thick film values, due to the small nanosized grains composing the films.     

纳米钛酸钡掺杂聚酰亚胺基高介电复合薄膜的制备及性能

采用原位聚合法和高速砂磨法制备了纳米钛酸钡/聚酰亚胺高介电常数复合薄膜,分析了不同制备方法及钛酸钡粉体用量对复合薄膜结构和性能的影响。实验结果表明,高速砂磨法对于纳米钛酸钡粉体的分散效果优于原位分散法;钛酸钡粉体的引入,有效提高了复合薄膜的热稳定性和介电性能。当粉体的体积分数达到50%时,复合薄膜介电常数相较于纯膜提高了10倍,而介电损耗只有少量增加。     

Non-linear optical effects in layer-by-layer alternate films of polycations and an azobenzene-containing polyanion

The technique of polycation/ polyanion layer-by-layer adsorption was applied to fabrication of non-linear optical films. Optical second-harmonic generation (SHG) was clearly observed from the films prepared by alternate adsorption of polycations and an azobenzene-containing polyanion (PAZO) on quartz substrate modified with polyion precursor. Regular film growth during adsorption cycles was proved by means of UV spectroscopy and quartz crystal microbalance technique. The SHG signal increased with the number of PAZO layers up to four layers, while further assembly reduced the signal. The SHG decreased considerably by heating the film up to 120 °C.