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。     

表面活性剂对水热合成掺镧锆钛酸铅陶瓷粉体物相及形貌的影响

以醋酸铅[Pb(CH3COO)2·3H2O]、硝酸镧[La(NO3)3·6H2O]、硝酸锆[Zr(NO3)4·5H2O]和钛酸四丁酯为原料,以KOH为矿化剂,水热合成了掺镧锆钛酸铅(lanthanum-modified lead zirconate titanate,PLZT)陶瓷粉体。研究了表面活性剂十六烷基三甲基溴化铵(cetyltrimethyl ammonium bromide,CTAB)对水热合成PLZT陶瓷粉体的作用。利用X射线衍射、扫描电子显微镜考察了所得到粉体的物相和形貌。结果发现:前驱体混合不均匀或反应时间较短时,粉体中均会生成针状La(OH)3颗粒。添加适量的CTAB能够抑制La(OH)3的生成,并且可以缩短合成单相PLZT陶瓷粉体所需要的反应时间。但过量的CTAB反而会促进针状La(OH)3颗粒的产生。     

热压烧结对锆钛酸铅镧陶瓷电卡效应的影响

探讨热压烧结工艺对PLZT(锆钛酸铅镧)陶瓷材料介电击穿性能、饱和极化强度以及电卡性能的影响。通过X射线衍射和扫描电子显微镜,分析陶瓷样品的相组成和微观结构。结果表明,热压烧结法有助于控制陶瓷晶粒的生长,提高陶瓷的致密度并增大陶瓷的介电击穿场强,从而有效提高陶瓷的电卡性能以及电卡转换效率。在328 K(55℃)与478 K(205℃)附近,分别发生低温铁电三方相到高温铁电三方相的相变(FRL-FRH)以及高温铁电三方相到立方顺电相(FRH-Pc)的相变,展现了比较好的弛豫性,在室温下达到3.6 K的绝热温变与1.8×0-7(K·m)/V的电卡转换效率,具有良好的电卡性能。     

La掺杂对PLZT压电陶瓷及PLZT/PVDF复合材料结构及特性的影响

分别采用固相反应烧结法和注模法制备（Pb1-xLax）（Zr0.5Ti0.5）1-x/4O3（x=0.01～0.13）锆钛酸铅镧（lead lanthanum zironate titanate,PLZT）压电陶瓷和0-3型PLZT/聚偏二氟乙烯（polyvinylidene fluoride,PVDF）复合材料。用X...     

PSN掺杂对锆钛酸铅特性的改善

研究了通过掺杂Ｐｂ（Ｓｎ１／３Ｎｂ２／３Ｏ３［ＰＳＮ］对Ｐｂ（ＴｉｙＺｒ２）Ｏ３系陶瓷热稳定性及老化特性的改善,试验表明加入一定量的ＰＳＮ组成的陶瓷体系,居里温度提高,高温下的热稳定性和老年特性均得以改善,满足了高温下高性能的压电换能元件的需要。     

锆钛酸铅镧压电陶瓷纤维的制备与性能

以锆钛酸铅镧[(Pb1-xLax)(Zr1-yTiy)O3,lead lanthanum zirconate titanate,PLZT]压电陶瓷为原料,用塑性聚合物法制备不同截面的PLZT陶瓷纤维。用X射线衍射、扫描电镜、密度测试仪、微力试验机和铁电分析仪分别测试PLZT陶瓷纤维的相结构、显微形貌、密度、力学性能和铁电性能。结果表明:PLZT陶瓷纤维为三方相钙钛矿结构,圆柱形纤维的直径和方柱形纤维的边长分别约250μm和300μm。圆柱形和方柱形纤维的最终抗拉伸强度和弹性模量分别为24.88MPa、6.90×103MPa和23.97MPa、5.71×103MPa。PLZT陶瓷纤维均具有良好的铁电性能,圆柱形纤维的饱和场强、剩余极化强度(Pr)和矫顽场(Ec)分别为10kV/mm、41.40μC/cm2和1.10kV/mm;方柱形的饱和场强、Pr及Ec分别为10kV/mm、41.68μC/cm2和1.03kV/mm。     

水热合成镧掺杂钛酸铋粉体的初步研究

初步研究了镧掺杂钛酸铋粉体的水热合成工艺,借助XRD及TEM对粉体的组成、结构、晶粒度及粉体形貌进行了研究。结果表明:合成该粉体的最佳工艺条件为240℃保温6h;粉体的微观形貌呈片状;镧的掺杂抑制了钛酸铋晶体的生长。     

溶胶-凝胶法制备钙钛矿型纳米钛酸铅粉体

以硝酸铅和钛酸丁酯为原料,采用溶胶-凝胶法制备了钙钛矿型纳米钛酸铅。利用XRD、FT-IR、SEM等分析测试手段,对制备的钛酸铅纳米粉体的结构、性质和形貌进行了表征。并讨论了乙醇、温度、PH值和热处理温度等因素对溶胶-凝胶过程的影响,结果表明,钛酸铅晶体在400℃时形成,随着热处理温度的升高,粉体的物相也会发出变化。     

钙掺杂对铬酸镧热膨胀系数的影响

利用固相法合成的铬酸镧粉制备铬酸镧样品。研究了钙掺杂量对铬酸镧样品热膨胀系数的影响。结果表明：当钙掺杂铬酸镧时,Ca^2＋于A位取代La^3＋,引起A位离子半径减小,晶胞参数发生变化,同时Cr^3＋变价形成Cr^4＋,引起了O^2--O^2-和Cr^3＋-O^2-键长、键角和键能相应改变,从而对铬酸镧样品的热膨胀系数和相变温度造成影响;从室温到1000℃,铬酸镧的热膨胀系数随钙掺杂量增加而增大,由正交结构向菱形结构转变的相变温度随钙掺杂量增加呈线性提高。     

掺镧的锆钛酸铅透明陶瓷材料在平板显示器上的应用

介绍了近年来平板显示技术的发展及４种平板显示器主要的优缺点,着重阐述利用掺镧的锆钛酸铅（ＰＬＺＴ）透明陶瓷材料铁电发射性能在场致发射平板显示器上的应用和它的电光效应在大型投影平板显示器件方面的应用,并分析了其发展趋势。     

钛酸钡掺杂镧电子陶瓷制备的研究

在钛酸钡陶瓷中掺入稀土多酸微量元素(0.1%～0.3%),会使钛酸钡陶瓷的电阻率降低,由绝缘变为半导体。那么减小杂量掺杂是否对钛酸钡陶瓷有同样的作用呢?为此在实验中采用溶胶-凝胶法制备掺杂稀土元素镧的钛酸钡纳米晶,考察了掺杂量分别为0.01%～0.05%和0.1%～0.5%的钛酸钡纳米晶的部分特征,以及杂质的掺入对钛酸钡粒径、煅烧温度和晶胞参数等方面的影响。     

水热合成掺镧钛酸铋粉体及其光催化性能探讨

以硝酸铋、四氯化钛和硝酸镧为原料,以氢氧化钾为矿化剂,采用水热法合成了不同镧掺杂量的钛酸铋粉体.用X射线衍射(XRD)和透射电镜(TEM)对所得粉体进行了表征,借助紫外-可见分光光度计考察了样品降解甲基橙的光催化性能.实验结果显示:在水热合成温度为220～280 ℃、保温时间为6 h的条件下,可得到各向异性、短轴为30 nm、长轴大于100 nm的掺镧钛酸铋粉体,且该方法所制备的掺镧钛酸铋(Bi 4-xLaxTi3O12)粉体具有一定的光催化效果.     

钛酸铅系电子陶瓷及粉体的制备方法

综述了钛酸铅系电子陶瓷及粉体的制备方法，主要讨论了水热法和溶胶一凝胶法的制备原理及影响产物性能的因素。为钛酸铅系功能陶瓷及材料的研究指明了方向。即用最新方法制备超纯、超细粉体，以先进技术指导合成降低反应温度并制备出功能复合材料。     

Impedance spectroscopy on pH-sensors with lithium lanthanum titanate sensitive material

The ceramic Li_3xLa_2/3−x,_1/3−2xTiO₃ is used, in an all-solid-state configuration, as pH-sensor in aqueous buffer solution. This ceramic displays a pH sensitivity comparable to the one obtained with a commercial glass electrode and does not show any sensitivity to the redox potential of the solution. This is one of the remarkable properties of this ceramic pH-sensor. It is shown in this paper that the reproducibility and the behaviour of the pH-response depend on the morphology of the grain boundaries particularly on the size of the grains. A so-called ‘good’ pH-response is obtained with a ceramic showing big and homogeneous grains. Complex impedance spectroscopy reveals that such ceramic has a high grain boundary resistance. Furthermore, this electrochemical technique allows us to determine that the interface reaction involved in the pH detection has a time constant of the order of the second. Several assumptions such as ion exchange or acid-base reaction are proposed to explain the sensitivity of the ceramic material to the pH of the solution.     

Influence of feedstock concentration on tetragonality and particle size of hydrothermally synthesized barium titanate powders

Barium titanate (BaTiO₃) powders were synthesized through hydrothermal process with Ba(OH)₂·8H₂O and TiO₂. By increasing the feedstock concentration (FC) from 0.25 to 1.50 M, BaTiO₃ powders maintain a stable average particle size (~180 nm and ~6.4441 m²/g) with an increasing tetragonality (c/a: 1.0065–1.0075). Johnson-Mehl-Avrami and standard reaction rate equations were adopted to analyze the kinetic process of BaTiO₃ formation. The reaction is governed by first-order and phase-boundary-controlled mechanism for 0.25 M and 1.50 M, respectively. Lower extent of reaction is believed to lead to the better tetragonality for BaTiO₃ powders fabricated with higher FC. On the other hand, the relative stable particle size is correlated with the unvaried nucleation frequency and grain growth rate with various FC. This work can provide a guideline to manipulate the properties of BaTiO₃ powders used in electronic industry.     

钙钛矿型纳米钛酸铅的制备

以无水醋酸铅和钛酸丁酯为原料,采用溶胶-凝胶法制备了钙钛矿型纳米钛酸铅（PbTiO₃）粉体。利用X射线衍射(XRD)、粒度测试、扫描电镜(SEM)等分析测试手段,对制备的钛酸铅纳米粉体的结构、性质和形貌进行了表征,并讨论了影响溶胶-凝胶过程的诸因素。研究结果表明:无水乙醇、水解温度、丙三醇和热处理温度等因素均对溶胶-凝胶过程有明显的影响,其中反应温度对胶体形成时间的影响最明显。钙钛矿型钛酸铅晶体在450 ℃时形成,随着热处理温度的升高,粉体的物相组成也将发生变化。钛酸铅干凝胶在600 ℃热处理2 h后可以得到结晶程度很高、平均粒径为53.7 nm、颗粒大小分布均匀的纳米钛酸铅粉体。     

Dielectric and ferroelectric properties of lanthanum‐modified lead zirconate stannate titanate (42/40/18) ceramics

The effect of lanthanum (La) content on the phase transformation of Pb_1?3x/2La_x(Zr_0.42Sn_0.40Ti_0.18)O₃ (PLZST 100x/42/40/18, 0 ≤ x ≤ 0.06) ceramics was investigated by the dielectric and ferroelectric properties. The base composition PLZST 0/42/40/18 located in the ferroelectric (FE) rhombohedral phase region. As x increased, the compositions showed successively FE and antiferroelectric (AFE) state at room temperature, and their peak temperatures (T_max) decreased gradually in line as T_max = 162.21‐1507x. Evidence was presented that there were two dielectric anomalies in PLZST 2/42/40/18, which were corresponding to the FE‐AFE and AFE‐paraelectric (PE) phase transformations, respectively. With increasing the dc bias fields, the two phases merged into one. PLZST 3/42/40/18 showed AFE characteristics with the first loop outside of the second loop and there was only one dielectric inflection. The critical lanthanum content occurred at x = 0.03 from the dielectric temperature spectra and hysteresis loops. Furthermore increase in La above 0.03, these compositions showed typical antiferroelectric behaviors with double hysteresis loops. The stored energy properties of the three compositions (PLZST 4/42/40/18, 5/42/40/18 and 6/42/40/18) displayed different temperature dependencies from room temperature to 140°C (over their respective T_max). Comparing the above results with previous investigations on PLZSTs, some questions were discussed.     

Effects of Solvent Mixtures on Dispersion of Lanthanum-Modified Lead Zirconate Titanate Tape Casting Slurries

The effects of xylenes/ethanol solvent mixtures on lanthanum-modified lead zirconate titanate (PLZT) nonaqueous suspensions were investigated by measuring sediment height, viscosity, and adsorption of dispersant. Well-dispersed colloidal suspensions were obtained in xylene-rich solvents with a minimum amount of menhaden fish oil as a dispersant. It was also shown that adsorption of dispersant on particle surfaces strongly depends on selection of solvent(s). The ratio of solvent mixture affects PLZT solids content of unfired tapes, in which using insufficient as well as excess dispersant could decrease the packing density of particles. Solubility of other organic additives, such as binder, was also considered when selecting a xylene/ethanol ratio.     

Influence of PbO content on the dielectric failure of Nb-doped {100}-oriented lead zirconate titanate films

A series of niobium-doped, {100} textured, “gradient free,” lead zirconate titanate (PNZT) films with different PbO contents were fabricated by the chemical solution deposition method. The films’ PbO content was controlled by changing the average PbO content in the solution from 114.7 to 117 at.%. During the dielectric breakdown process of 1.5 μm thick PNZT films with Pt top and bottom electrodes, two phenomena were observed: cracking and thermal breakdown of the piezoelectric film. At 150°C, with an applied 400 kV/cm electric field, the crack density of PNZT films induced by electromechanical failure increased from 0.060/μm to 0.090/μm as the solution's PbO content increased from 114.7% to 117%. In addition, the films showed higher crack densities and more frequent thermal breakdown events when the electric field was oriented downward (from top to bottom electrode) compared with an upward oriented electric field (from bottom to top electrode). The films with higher PbO content had a lower breakdown strength. Also, all films showed lower breakdown strength when measured in the field down direction. The Schottky barrier height (SBH) decreased from 0.82 ± 0.06 to 0.68 ± 0.04 eV in the field up direction measurement as the PbO content increased. The SBH value did not show significant change in the field down direction measurement. This suggests that the asymmetry in the film/electrode interfaces is a function of the PbO content in the original solution.     

钛酸铅系薄膜的溶胶-凝胶法制备及其应用

简单介绍了钛酸铅系薄膜的制备方法，分析了溶胶-凝胶法较其它方法的优点。探讨了钛酸铅溶胶的稳定因素，如原料、溶剂、添加剂的选取。阐述了热处理温度、时间，退火温度、时间，基片和过渡层对促进钛酸铅系薄膜晶化的影响，并对钛酸铅系薄膜的应用现状进行了概括，展望了钛酸铅系薄膜的发展前景。