Sol-Gel法制备择优取向铁电陶瓷薄膜的研究进展

综述了溶胶—凝胶法制备择优取向铁电陶瓷薄膜的研究现状,主要介绍了制备过程中衬底材料、热处理工艺、前驱体以及掺杂等因素对铁电陶瓷薄膜择优取向的影响以及铁电陶瓷薄膜的择优取向与铁电性能的关系。     

Sol-Gel法制备择优取向铁电陶瓷薄膜的研究进展

综述了溶胶—凝胶法制备择优取向铁电陶瓷薄膜的研究现状,主要介绍了制备过程中衬底材料、热处理工艺、前驱体以及掺杂等因素对铁电陶瓷薄膜择优取向的影响以及铁电陶瓷薄膜的择优取向与铁电性能的关系。     

强电流铁电陶瓷材料研究

强电流铁电陶瓷是一种组成结构为铁电相与反铁电相共存，而极化后为铁电相和亚铁电相的特种功能材料。该项目在四种材料中优选出一种缺位型新材料，采用等静电成型，极化前高温退火及高温极化工艺技术，制备了平行发射和垂直发射的铁电阴极样品，通过对电极边缘的绝缘保护处理增大了激励场强，提高了发射电流强度，通过SEM，XRD及晶胞参数测定等微观结构分析，验证了快速化反转引起电子发射机理的正确性，研究了结构缺陷，局部相变与电子发射特性的关系，为铁电阴极材料的开发应用提供了理论基础。     

铁电薄膜及其制备技术

具有铁电性且厚度尺寸为数十纳米到数微米的铁电薄膜具有良好的压电性、热释电性、电光及非线性光学特性 ,在微电子学、光电子学、集成光学和微电子机械系统等领域有着广泛的应用前景 ,是目前国际上新型功能材料研究的热点之一。通过综述铁电薄膜及其制备技术研究的新进展 ,给大家介绍铁电薄膜材料的基本特征、性能及应用 ,并重点分析铁电薄膜主要制备技术的优缺点 ,指出了目前铁电薄膜及其制备技术研究需要重点解决的一些问题。     

(Ba,Sr)TiO3铁电薄膜制备技术及其研究进展

(Ba,Sr)TiO3(简称BST)铁电薄膜较传统的铁电材料有高介电常数、高击穿场强、快响应速度、居里温度可调等优点,在DRAM、微波调节器等领域具有广阔的发展前景,是目前国际上新型功能材料研究的热点之一.通过对铁电薄膜及其制备技术研究新进展的综合评述,就BST的微观结构、性能及应用,深入分析BST铁电薄膜主要制备技术的优缺点,指出了目前铁电薄膜及其制备技术研究中应注意的问题.     

人工复合铁电薄膜的相变性质研究

建立3层铁电复合薄膜的理论模型,在G inzburg-Landau-Devonsh ire（GLD）唯象理论的框架下,引入局域分布函数描述不同材料间过渡层的性质,重点研究具有不同相变温度的铁电材料复合而成的铁电薄膜的相变性质.通过改变3种不同铁电材料的相变温度,计算复合铁电薄膜内部的极化强度分布和相变温度.研究表明：3种铁电材料相变温度的梯度变化导致了复合薄膜内部极化分布的梯度变化;在未达到薄膜的相变温度前,薄膜的平均极化强度的一阶导数出现了一个突降,造成了平均极化强度的极大降低;不同材料间过渡层厚度对薄     

（Ba，Sr）TiO3铁电薄膜制备技术及其研究进展

(Ba，Sr)TiO3(简称BST)铁电薄膜较传统的铁电材料有高介电常数、高击穿场强、快响应速度、居里温度可调等优点，在DRAM、微波调节器等领域具有广阔的发展前景，是目前国际上新型功能材料研究的热点之一。通过对铁电薄膜及其制备技术研究新进展的综合评述，就BST的微观结构、性能及应用，深入分析BST铁电薄膜主要制备技术的优缺点，指出了目前铁电薄膜及其制备技术研究中应注意的问题。     

溶胶-凝胶法制备PbTiO3薄膜的研究

采用溶胶-凝胶(Sol-Gel)法制备了PbTiO3(PT)铁电薄膜,对薄膜的形貌、结晶等性能进行了表征,对铁电薄膜材料的介电、铁电、热释电性能进行了研究分析.     

用于纳米铁电材料介电性能测试的粉体电极

铁电材料的尺寸效应是当今材料科学的研究热点,由于测试技术上的限制,传统测试方法难以保持材料的纳米状态,测试结果不能表征纳米铁电材料的性能特征。因此,提出了一种粉体电极,可直接用于测试纳米级粉体材料的介电性能,并以钛酸钡材料为例介绍了实验测试方法及结果。     

铁电薄膜及其制备技术

具有铁电性且厚度尺寸为数十内米到数微米的铁电薄膜具有良好的压电性、热释电性、电光及非线性光学特性，在微电子学、光电子学、集成光学和微电子机械系统等领域有着广泛的应用前景，是目前国际上新型功能材料研究的热点之一。通过综述铁电薄膜及制备技术研究的新进展，给大空介绍铁电薄膜材料的基本特征、性能及应用、并重点分析铁电薄膜主要制备技术的优缺点，指出了目前铁电薄膜及其制备技术研究需要重点解决的一些问题。     

高取向钛酸铋陶瓷铁电和介电性能研究

采用改进的固相烧结法，制备出具有高c轴取向的Bi4Ti3O12铁电陶瓷样品，从对样品的铁电、介电测量中可以看出，样品的取向性对样品的铁电性能（剩余极化、矫顽场）、漏电流、介电性能等都产生了影响。     

Ab Initio Study of Doping Mechanisms in Ba TiO_3-BiYO_3

A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_(Ba),Y_(Ti)) in BaTi O_3-BiYO_3. Single Bi_(Ba) and Y_(Ti) impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed [YO_6] octahedral in single Y impurity. However, in the co-doped Bi_(Ba) and Y_(Ti) structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti~(4+) difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO_3 ceramic matrix.     

表面效应对铁电纳米线性能的影响

在Jandau-Ginsburg-Devonshire(LGD)理论的基础上,建立了铁电纳米线的理论模型,并通过与第一原理计算结果的对比,建立了一种获取外延长度的新方法.对于Pb(Zr0 5 Ti0.5)0,(PZT)纳米线,其外延长度为20 nm.计算结果表明,在PZT纳米线中存在O.8 nm的临界直径,同时揭示了纳米线的表面效应对其铁电性能的抑制作用.     

LaAlO3电子结构及顺电特性的第一原理计算

采用基于密度泛函理论的第一原理计算方法,研究了立方相的LaAlO3(LAO)晶体的电子结构及其在外延应力作用下的相变势能面特征和波恩有效电荷值.计算结果表明,在LAO中La-d、Al-s、p及O-p轨道电子占主要作用,Al-O的轨道杂化作用相对比较大.在平面晶格应力的作用下,考量Al-O八面体畸变对相变势能面的贡献,发现其势阱曲线表现出与传统铁电材料经典的双阱曲线不同的单阱曲线,进一步的波恩有效电荷的计算表明,其原因可能是Al-O的轨道杂化作用(电荷转移)没有达到铁电畸变所需的能量,而使LAO成为顺电体.     

K0.5Bi0.5TiO3:ZnO无铅铁电复合陶瓷的退极化行为

为了抑制K_(0.5)Bi_(0.5)TiO_3的退极化现象,提高铁电性能,以K_2CO_3、TiO_2、Bi_2O_3及ZnO为原料,通过二步固相法合成无铅铁电复合陶瓷K_(0.5)Bi_(0.5)TiO_3:ZnO(KBT:ZnO).通过X射线衍射、扫描电子显微镜、铁电和介电测试分析了复合陶瓷的微观结构和介电行为.结果表明:KBT中引入20%(物质的量百分数)的ZnO后,复合陶瓷中生成了第三相Zn2TiO_4,同时,KBT的极化能力及其铁电行为得到改善.阻抗测试表明复合铁电陶瓷内部只存在一种导电机制,即电子电导.特别是ZnO的引入抑制了KBT由正常铁电体向弛豫铁电体的相转变,对KBT的应用和研究有着重要的作用.     

Ferroelectric relaxor as a critical state

After revisiting models for the ferroelectric relaxors, we notice that the models can be classified into two categories. One group models are directly based upon the compositional fluctuations, such as Smolenskii's theory and SRBRF model. The other models are experimental phenomenon oriented, such as macro-micro domain crossover and superparaelectric state. The later explanations imply that the ferroelectric relaxor is in a critical state. The unusual field induced phase transition in ferroelectric relaxor also suggests that this is a critical phenomenon with first order phase transition feature. Therefore within the framework of effective field approach and with introducing the concept of quantum temperature scale, we reproduce the diffused phase transition of the dielectric constant and the field induced phase transition. It seems that the larger quantum fluctuation at low temperature depresses the ferroelectricity in ferroelectric relaxors, and results in their unusual physical properties.     

<Emphasis Type="Italic">Ab initio</Emphasis> study of doping mechanisms in BaTiO<Subscript>3</Subscript>-BiYO<Subscript>3</Subscript>

A density functional plane-wave pseudopotential method is used to study the doping mechanisms of impurity defects(Bi_Ba, Y_Ti) in BaTiO₃-BiYO₃. Single Bi_Ba and Y_Ti impurities have little structure distortion. Bi forms ionic bond with nearby O atom in single Bi impurity, Y formed [YO₆] octahedral in single Y impurity. However, in the co-doped Bi_Ba and Y_Ti structure, Bi formed three valence bonds with nearby O atom, which causes the large structure distortion. The doped ion makes the mobile of Ti⁴⁺ difficult and loss local ferroelectricity, which will broaden the dielectric constant temperature curve and increase the temperature stability of BaTiO₃ ceramic matrix.     

MZr0．5Ti0.5O3（M=La，Nd，Ce）的制备及其铁电性能测试

采用改进的硬脂酸法制备了系列MZr0.5Ti0.5O3（M=La,Nd,Ce）陶瓷粉体材料。考察了MZr0.5Ti0.5O3的电滞回线,在此基础上通过电滞回线测试了CeZr0.5Ti0.5O3对温度和电场频率的响应情况。结果表明：LaZr0.5Ti0.5O3。和CeZr0.5Ti0.5O3具有一定的电滞特性,但电滞回线并不完全对称;在本实验条件下,NdZr0.5Ti0.5O3不具备铁电性;温度升高,CeZr0.5Ti0.5O3的剩余极化强度也提高;测试电场频率降低,内偏场的数值也随之降低,而矫顽电场、剩余极化强度则明显提高。     

Fabrication of sub-micro size PZT array and their ferroelectric properties

The photosensitive PZT sols and their gel films were prepared by sol-gel process. Based on the photosensitivity of the PZT gel films, two-dimensional (2D) array of the PZT gel film was fabricated using twice-exposure of double-beam interference on the gel film. PZT gel films coated on ITO/quartz substrate were exposed to an interference fringe of 325 He-Cd laser beams, the substrate was rotated by 90° between the first and second irradiation steps. Island type periodic 2D array structures with a pitch of 1 μm and cell size of about 480 nm × 480 nm × 40 nm were formed after the irradiation, and followed by leaching with organic solvent, and then by heat treatment at 600℃ for 15 min. The hysteresis loops of the cell in PZT array were in-situ measured by the online-operation of TF analyzer and atomic force microscope (AFM). The probe can be located on the locked cell of PZT array in the AFM image. The alternating voltage applied to the locked cell is supplied by the TF analyzer through the conductive coating probe, and then the test signal is fed back to the TF analyzer to obtain the hysteresis loop of the locked cell of array in the absence of top electrode. The results show that the sub-micro size PZT arrays prepared in this way are of polarization reversal characteristics with the alternating electric fields, thereby exhibiting obvious ferroelectricity.     

生物除磷系统不同阶段性能及微生物群落分析

为探讨工艺运行与微生物群落的关系,在厌氧/好氧SBR反应器中考察生物除磷系统的启动期、稳定期和恶化期的性能,并利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术研究该系统各阶段功能微生物群落结构特征.启动期历时26d,包括适应期和上升期两个阶段,磷的去除率从40%以下提高到80%,之后进入稳定期,磷去除率维持在80%以上.稳定期的功能微生物为Tetrasphaera elongate,Gemmatimonas aurantiaca和Uncultured γ-proteobacterium.稳定运行80d后进入恶化期,磷去除率降到70%以下.恶化期和稳定期的微生物群落结构差别很大,功能微生物Uncultured γ-proteobacterium被淘汰,竞争菌Candidatus Competibacter phosphatis clone SBRQ22显著增加.