SrBi4Ti4O15/Ag复合材料的制备及其介电特性

采用固相烧结工艺制备了SrBi4 Ti4O15(SBTi)/Ag铁电复合材料,用X射线衍射、光学金相显微镜和扫描电子显微镜对材料的组成和微观结构进行了研究,并测量了样品的介电温度谱。结果表明：复合材料是由SBTi和Ag两相组成。金属Ag的加入使SBTi铁电陶瓷的烧结温度从1120℃降低到950℃以下。随着烧结温度的提高,Ag颗粒的尺寸增大,但SBTi晶粒并无明显变化。Ag的加入可以适当提高铁电陶瓷从室温到200℃的介电常数,但对材料的介电损耗影响很小。同时Ag的加入抑制了介电温度曲线介电常数的Curie峰。     

底电极原位退火与沉积温度对PZT薄膜性能影响研究

采用磁控溅射工艺,在Pt/Ti底电极上沉积锆钛酸铅(PZT)薄膜,研究了原位退火温度与底电极沉积温度对溅射PZT薄膜结晶取向、微观结构、介电性能、铁电性能及疲劳性能的影响。X射线衍射(XRD)和扫描电子显微镜(SEM)分析结果表明,随着电极沉积温度升高,Pt晶粒尺寸增大,随着退火温度升高,PZT薄膜致密性变差。对室温制备的Pt/Ti底电极进行200 ℃原位退火30 min后,易于促进PZT薄膜沿(100)择优取向,而高温制备或经高温退火处理的Pt/Ti底电极更有利于PZT薄膜的(111)晶向生长。电学性能分析表明,室温制备的Pt/Ti底电极在经200 ℃原位退火30 min后,其PZT薄膜介电性能最优,同时展现较高的剩余极化强度和最小的矫顽场强,经历10⁸次极化翻转后,初始极化下降仅为11％。     

制备工艺对溶胶-凝胶法制备BeFeO3薄膜的影响

利用溶胶-凝胶法在Pt/Ti/SiO2/Si基体上制备了BiFeO3薄膜,构架了Pt/BiFeO3/Pt电容器。对不同退火温度和保温时间制备薄膜的微观形貌和铁电性能做了研究。X射线衍射仪（XRD）结果显示,不同的退火温度和保温时间并没有改变BiFeO3（BFO）的钙钛矿结构,但温度的改变会产生不同的晶相。通过扫描电子显微镜（FE-SEM）可以观察到,随着烧结保温时间的延长,薄膜晶粒有减小的趋势。P-E曲线结果表明,BFO薄膜在外加电场较高时易击穿,难以得到清晰饱和的电滞回线。     

熔盐法合成片状BaBi_4Ti_4O_(15)粉体

以NaCl-KCl作为熔剂,采用熔盐法首次合成了(0010)晶面择优取向的片状BaBi_4Ti_4O_(15)粉体.研究了预烧温度及熔盐含量等因素对粉体显微形貌的影响,分析了这些因素对BaBi_4Ti_4O_(15)粉体沿(0010)面取向生长的影响.结果表明:随着预烧温度的升高及时间的延长,颗粒粒径尺寸不断增加,(0010)衍射峰强度先增强后减弱.当熔盐与原料的质量比R≠1时,随熔盐含量增加颗粒粒径尺寸先增大后减小;当R=1时,1 050℃预烧4h后得到的片状粉体呈(0010)面取向,粒径分布均匀,平均粒径约5.9μm,厚0.5μm.     

热处理工艺对钙锶铋钛铁电薄膜性能的影响

用溶胶-凝胶法和快速退火技术在带白金电极和钛过渡层的硅片(Pt/Ti/SiO2/Si)上制备了钙锶铋钛(Ca0.4Sr0.6Bi4Ti4O15,CsBT-0.4)铁电薄膜.结果表明:退火温度及保温时间对CSBT-0.4铁电薄膜的微观结构、晶粒取向以及铁电性能的影响较大.x射线衍射谱表明:退火温度为750℃、保温时间为5min,得到的CsBT-0.4铁电薄膜样品的晶粒大小较均匀且致密性好,而且晶粒以a轴取向的球状晶粒为主,剩余极化强度(2Pr)和矫顽场(2Ec)分别为16.2 μC/cm2和130kV/cm.     

界面增强型PVDF/PET膜的制备及性能

通过对支撑材料进行表面改性处理和浸入凝胶法制备了界面增强型聚偏氟乙烯/聚对苯二甲酸乙二醇酯（PVDF/PET）超滤膜。用电导率在线测量法确定了硅烷偶联剂 3-氨丙基三乙氧基硅烷（KH550）水解液的制备条件,考察了改性处理条件对PVDF/PET膜的界面性能和力学性能的影响。通过180°剥离试验测试PVDF膜与支撑层间的剥离强度,用扫描电镜观察PET无纺布及PVDF膜破坏底面的微观形貌,用傅里叶红外光谱仪表征PET表面化学组成。结果表明,水解液中KH550用量较少时（≤3%）,处理时间延长,PVDF/PET间的剥离强度增大,水解液中KH550用量较多时（>3%）,处理时间延长,PVDF/PET间的剥离强度先增大后减小;PVDF/PET膜的拉伸强度随水解液中KH550用量的增加或处理时间的延长先增大后略减小。改性前后PVDF/PET膜的分离与透过性能对比表明,PET表面改性后,PVDF膜的牛血清白蛋白（BSA）截留率几乎不受影响,水通量略增。     

聚氯代对二甲苯膜的退火处理及热氧老化研究

采用化学气相沉积法制备聚氯代对二甲苯(PPXC)膜,并对其在氩气和空气2种气氛中进行退火处理,研究退火前后PPXC膜的微观结构、拉伸强度及水汽渗透率变化.结果表明,PPXC膜在2种气氛下恒温退火,聚合物的结构变化存在2个过程,结晶完善过程与降解过程,在大气中氧的存在增大了降解程度.PPXC膜的拉伸强度随退火时间先增大、后减小,而水汽渗透速率则随退火时间先减小、后增大.且在氩气气氛中,PPXC膜所达到的力学性能、水汽阻隔性能更佳.     

晶粒尺寸和膜厚对磁控溅射法制备Bi_(1.5)Mg_(1.0)Nb_(1.5)O_7薄膜介电性能的影响（英文）

采用磁控溅射法在Pt/Ti/Si O2/Si基底上制备立方焦绿石结构Bi1.5Mg1.0Nb1.5O7薄膜。通过控制750℃下后退火时间来控制薄膜的平均晶粒尺寸,用沉积时间控制膜厚。研究不同晶粒尺寸和膜厚对BMN薄膜相结构、微观形貌和介电性能的影响。结果表明,当BMN薄膜平均晶粒尺寸为45 nm、膜厚为430 nm时,薄膜介电性能提高显著,1 MHz下介电常数为112.4,介电损耗为0.001 82,在0.93 MV/cm外加电场条件下,介电调谐率为27.7%。     

硅基铌掺杂Bi_4Ti_3O_(12)薄膜溶胶-凝胶工艺的制备及铁电性改善研究

采用溶胶-凝胶(Sol-Gel)法制备了铌元素(Nb)取代Ti元素的Bi4Ti3O12(BTN)铁电薄膜,研究不同掺杂浓度,不同退火温度等工艺对BTN薄膜的微观特性及剩余极化强度、矫顽场等电性能的影响。研究表明,650℃进行退火的BTN薄膜生长形态,晶粒开始呈棒状生长;当温度高于850℃时,薄膜的c轴生长取向增长趋势不再明显。铁电性方面,对Ti进行2%掺杂取代的BTN薄膜的铁电性能最佳。从而获得了BTN薄膜制备的合理工艺参数。     

不同水浴时间对纳米TiO2材料的影响

本文以钛酸丁酯Ti（OC4H9）4冰醋酸、去离子水和无水乙醇为原料,采用溶胶一凝胶法,制备了纳米二氧化钛胶体和粉体,并用旋转涂片法在玻璃衬底上沉积了不同层数的纳米Ti02薄膜。然后对纳米Ti（）2薄膜与粉体进行热处理。利用X射线衍射仪（XRD）、紫外可见光谱（UV／vis）、扫描电镜（sEM）对纳米二氧化钛粉体与薄膜进行表征。结果表明,500℃和600℃下,样品均产生锐钛矿结构。随着镀膜层数的增加,薄膜的透射率逐渐下降。相同镀膜层数,随着水浴时间的增加,透射率呈现增加的趋势。通过对光学带隙的计算,表明退火温度对光学带隙有影响。     

掺锶对钛酸铅薄膜结晶性能的影响

钛酸锶铅(PST)薄膜是一类重要的铁电薄膜材料.采用溶胶-凝胶法在硅(100)衬底上制备了钛酸锶铅薄膜.利用X射线衍射(XRD)、原子力显微镜(AFM)等表征手段,表征了不同锶掺杂量及不同退火温度对薄膜结晶性能的影响.通过实验发现:锶掺杂对薄膜的微观结构和表面形貌有重要的影响.由XRD谱图发现,随着锶掺入量的增加,Pb 1-xSrxTiO3薄膜中的晶轴比、晶胞体积都逐渐减小,晶化温度降低.通过AFM发现,相同掺锶量的薄膜随着退火温度的升高,结晶性能增强,颗粒增大,粗糙度增加.     

Texture Development in Modified Lead Titanate Thin Films Obtained by Chemical Solution Deposition on Silicon-Based Substrates

An advanced method of X-ray diffractometry analysis, the quantitative texture analysis, is used in this work to study the preferential orientations of ferroelectric lanthanum-modified lead titanate thin films, to establish the factors affecting their development. The new, more reliable, texture data obtained allows us to discuss previous models of texture development in chemical-solution-deposited films. The results show that a fiber type, mixed <100>,<001> preferential orientation, is obtained when high heating rates are used during crystallization. The degree of texture of these films decreases when successive layers are deposited before a simultaneous crystallization of the ensemble is conducted. This undesirable effect is avoided through layer-by-layer crystallization, because of the preferential nucleation of <100>,<001> crystals at the interface between layers. The use of a titanium layer on the platinized silicon-based substrate leads to the development of an additional fiber <111> texture component. In this case, the layer-by-layer crystallization process cannot avoid the loss of the degree of orientation (texture index) with the increase of film thickness. This is mainly caused by the appearance of interlayer porosity, which disrupts the growth of <111>-oriented grains into upper layers.     

溶胶-凝胶法制备钛酸锶钡铁电薄膜的研究

钛酸锶钡(BST)薄膜是一类重要的铁电薄膜材料。采用溶胶-凝胶法制备了不同组分的具有钙钛矿结构的BST薄膜。利用X射线衍射技术(XRD),研究了不同退火条件下BST薄膜的结晶特性,结果表明制备的BST薄膜形成了单一的钙钛矿结构;利用扫描电子显微镜(SEM)和原子力显微镜(AFM)观察了薄膜的表面形貌,结果表明制备的BST薄膜光滑,平整,无明显的孔洞和裂纹,且生长良好。BST薄膜的晶粒细致,排列整齐,分布均匀,呈现球状。     

Hydrothermal Synthesis of Bismuth Titanate Powders

Bismuth titanate was synthesized under hydrothermal conditions from an amorphous bismuth–titanium precursor gel. The gel was formed by mixing a bismuth acetate complex with titanium butoxide and then adding the solution dropwise into 6 M NaOH. The resulting gel suspension was reacted under hydrothermal conditions at temperatures ranging from 160° to 200°C to form crystalline bismuth titanate. The gel crystallization kinetics increased with temperature, which resulted in 100% crystalline bismuth titanate in 5 h at 200°C. Wavelength-dispersive spectroscopy data indicated that sodium was incorporated into bismuth titanate during processing, and X-ray diffractometry suggested that the powder was composed of the Bi₅Ti₄O₁₅ phase. Transmission electron microscopy micrographs showed that the gel particles decomposed to 100–200 nm crystalline bismuth titanate particles during hydrothermal processing.     

Recent Materials Characterizations of [2D] and [3D] Thin Film Ferroelectric Structures

A review is given of ceramic and single-crystal thin film ferroelectric oxides, emphasizing perovskite phases, together with some new developments on hafnia films. It is shown that single-crystal barium titanate films behave as bulk down to at least 77 nm, with no finite size effects, no phase transition temperature shifts, and no dielectric peak broadening or change from first- to second-order transitions, suggesting that the gradient defect model of Bratkovsky and Levanyuk correctly describes such effects as extrinsic in experimental studies of equally thin ceramic thin films. In ceramic barium–strontium titanate (BST) thin films, it is shown that there is also no intrinsic broadening or shifts in phase transitions, with sharp, unshifted, bulk-like transitions observed only as re-entrant upon warming from cryogenic temperatures; this shows that phase transitions in ceramic thin films are dominated by kinetics and not thermodynamics and are definitely not equilibrium measurements. At high fields (>1 GV/m), the films exhibit space charge-limited conduction; no variable-range hopping is observed, contrary to recent studies on SrTiO₃. Some novel, unconventional switching processes are discussed, comparing the "perimeter effect" (non-equilibrium, ballistic) with Molotskii's equilibrium model. Theory and experiment are described for [3D] nanotubes, nanorods, and nano-ribbons (or micro-ribbons). The layered-structure-perovskite–pyrochlore conversion in bismuth titanate is described together with the PbO+TiO₂ phase separation in lead zirconate titanate during electrical breakdown, as are novel HfO₂ precursors that demonstrate enhanced temperature crystallization from the amorphous state and hence commercial advantages for front-end processing.     

Impurity Phases in Polycrystalline Films of Ferroelectric Oxides of the Perovskite-Type on the Basis of Bi<Subscript>2</Subscript>SrTa<Subscript>2</Subscript>O<Subscript>9</Subscript> and Pb(Zr,Ti)O<Subscript>3</Subscript>

Processes of the formation of inclusions of impurity phases in lead zirconate titanate and strontium bismuth tantalate (SBT) films by changing the excess concentration of the most volatile cation component and temperature-time regimes of their formation are studied. The conditions in which the introduction of an excess Pb content does not lead to the formation of impurity phases are selected.     

Effect of Ru and LaNiO3 barrier layers on lead zirconate titanate films grown on nickel-based metal foils by sol–gel process

Lead zirconate titanate [Pb(Zr_0.52, Ti_0.48)O₃ (PZT)] films were grown by sol–gel process on nickel and hastelloy foils. PZT perovskite phase was obtained at 650 °C annealing condition and surface topography showed uniform and dense microstructure. The characterization on dielectric properties indicates that diffusion of foil elements into the PZT and the formation of low capacitance interfacial layer occur during process. In order to reduce the diffusion effect of foil element and/or interfacial layer, barrier layers such as Ru(RuO₂) and LaNiO₃ layers were utilized on foil substrates. The increase of grain size was observed in PZT films grown on barrier layers. Dielectric properties are greatly improved without degrading ultimate dielectric breakdown strength.     

Effect of poly(vinyl acetate) on structure and property of bismuth-doped strontium titanate thin films derived by sol–gel method

Bismuth-doped strontium titanate thin films with pure perovskite phase have been successfully deposited on Pt (1 1 1)/Ti/SiO₂/Si substrate by polymer-assisted sol–gel method. Poly(vinyl acetate) (PVAc) in precursor solution promoted the formation of perovskite phase during the heat treatment. SEM results revealed an increasing thickness from 40 to 80 nm every single layer and a porous structure with the addition of PVAc. The addition of polymer made the dielectric constant decrease from 140 to 40 and the tunability slightly increase compared with films without polymer in precursor.     

镧掺杂钛酸铋铁电薄膜的研究进展

综述了镧掺杂钛酸铋的有关理论,详细介绍了目前镧掺杂钛酸铋铁电薄膜的制备方法、优缺点及其进展。讨论了工艺因素对薄膜性能的影响。认为镧掺杂钛酸铋铁电薄膜是一种具有应用前景的光电材料。     

Characterization of Lithium Niobate Thin Films Derived from Aqueous Solution

Lithium niobate (LiNbO₃, LN) films prepared from aqueous precursor solutions were characterized, in terms of the hydroxyl contents on the surface layers through crystallization and optical properties. Approximately 98% of the hydroxyl residues on the surface layers of crystalline films were polymerized after heat treatment at 350° or 500°C, whereas 50% of the hydroxyl residues remained on the surface layers of amorphous films heat-treated at 200°C. Highly preferred oriented LN films had a tendency to consist of in-plane rotation by 60° during nucleation and crystallization. Optical losses (at 632.8 nm) were 2 dB/cm in the TE₀ mode and 4 dB/cm in the TM₀ mode of the LN films (thickness of 670 nm) on sapphire (001) substrates prepared from a neutralized precursor solution after annealing in oxygen at a temperature of 500°C (where TE and TM are the transverse electric and magnetic modes, respectively).