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。     

掺Tb3+钛酸铅粉末的制备和结晶行为

采用溶胶喂胶法制备了Tb^3 掺杂钛酸铅(PbTiO3，PT)超细粉末，分别用差热分析、透射电子显微镜、X射线衍射仪对其相结构、形貌特性以及晶粒粒径等进行了分析测试。结果表明：这种粉末在约600℃热处理温度下，由非晶基体转变形成钙钛矿相的过程已逐步完成，其晶粒平均尺寸约为18nm，比未掺Tb抖的PT粉末中的钙钛矿晶粒尺寸略小。形成的钙钛矿结构中，Tb^3 取代Pb^2 进入晶格位置，产生阳离子空位，诱发晶格畸变，使钙钛矿相的析晶能力比相同热处理条件下未掺杂Tb^3 的PT低。另外，掺Tb^2 的PT中钙钛矿相的晶轴比c／a比未掺Tb^3 的PT中的低，这类似于产生了赝立方结构，降低了从立方相向这种四方相转化的势垒，有效地抑制了较高温下焦绿石相的产生，使掺Tb^3 的PT中焦绿石相稳定存在的温度比未掺Tb^3 的PT中低约100℃。     

掺杂工艺对Al-F共掺ZnO薄膜性能的影响

采用溶胶-凝胶旋涂工艺在普通玻璃基片上制备出Al-F共掺杂ZnO薄膜,共掺杂离子浓度从0．25％增加到1．25％,退火气氛分别为空气、氢气和氩气,退火温度均为450℃。利用SEM测试方法研究了共掺杂离子浓度和退火气氛对薄膜表面形貌的影响;用紫外-可见分光光度计及四探针法等仪器对其对其透光性以及电阻率进行了测试,进一步研究了退火气氛对薄膜光电性能的影响。结果表明：制备的Al-F共掺杂ZnO薄膜多数表面平整,晶粒致密均匀;各种气氛下制备的薄膜在可见光大部分范围内透过率均超过80％;通过比较不同气氛下各种薄膜的电阻率,得知在H2气氛中退火处理后其电阻率最低为9．36×10^-2Ω·cm;与单一掺杂Al离子或F离子的薄膜相比较,Al—F共掺ZnO薄膜电阻率最低。     

冰醋酸对溶胶-凝胶法制备钛酸铅陶瓷纤维的影响

溶胶-凝胶法制备钛酸铅陶瓷纤维的好坏直接取决于溶胶的质量。采用冰醋酸作为催化剂,重点研究了冰醋酸的用量对溶胶的稳定性、产物的物相组成以及纤维形貌的影响,从而得出了合成稳定溶胶的最佳冰醋酸用量。     

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。     

过氧钛酸溶胶前驱体制备TiO2薄膜及其光催化性能

介绍了一种新型制备二氧化钛光催化薄膜的无机盐溶胶一凝胶法。以TiOSO4、氨水为原料,H2O2为络合剂制备了黄色、透明、稳定的中性过氧钛酸(peroxo titanic acid,PTA)溶胶。以PTA溶胶为前驱体,在玻璃片上经500℃热处理30min制备了透明的锐钛矿相TiO2光催化薄膜。用X射线衍射、扫描电镜、热重一差热分析等对PTA溶胶和TiO2薄膜进行了表征。结果表明：保持pH值呈中性可以制得透明PTA溶胶,该溶胶在200℃就产生了锐钛矿晶相。薄膜表面晶粒呈长条状,长100nm,径向直径40nm,加入聚乙二醇后,薄膜产生了孔径为20nm的多孔结构。以10mg／L甲基橙为降解对象初步考察了TiO2薄膜的光催化性能,在紫外光照120min内,其脱色率达到98．95％。     

镀膜工艺对溶胶-凝胶法制备钛酸铝薄膜的影响

采用溶胶-凝胶法,以钛酸四丁酯(Ti(OC4H9)4)和硝酸铝(Al(NO3)3·9H2O)为前驱体,乙醇为溶剂,利用硝酸铝中所含的结晶水代替水解反应所需的外加水,在莫来石基片上制备钛酸铝薄膜.借助偏光显微镜、SEM和XRD研究了提拉速度、浸渍时间和镀膜次数等镀膜工艺参数对镀膜效果的影响.研究结果表明:采用浸渍-提拉法,浸渍提拉速度为1mm/s、每次浸渍时间为30s,经过3次镀膜可以在莫来石基片上制备出均匀、致密、高质量的钛酸铝薄膜.     

制备过程对掺铝氧化锌薄膜性质的影响

文章采用溶胶-凝胶法在玻璃基底上制备得到了高透光率,高导电性的掺铝氧化锌薄膜（AZO）,利用原子力显微镜、扫描电镜、X射多次退火的制备过程不仅可以得到可见光区透光率大于85%,电阻率为7.2×10-5Ω·m的透明导电薄膜,而且因省略了热处理过程而简化了制备工艺,缩短了制膜时间。线衍射仪和紫外可见分光光度计等研究了三种不同的制备过程对AZO性质的影响。结果表明,制备过程的不同导致了薄膜的表面形貌、结构和导电性质方面的差别,其中分层多次退火过程有利于晶粒长大,形成结晶度高且具有单一（002）取向的AZO薄膜,同时改善薄膜的导电性能。分层     

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。     

铅-二氧化钛薄膜的制备与光催化性能研究

以钛酸丁酯为前驱体,醋酸铅为铅物种掺杂给体,采用溶胶-凝胶法制备经铅掺杂改性的二氧化钛溶胶,利用浸渍提拉法在普通玻璃片上制备铅-二氧化钛薄膜,利用X射线衍射（XRD）及扫描电镜（SEM）测试手段对制备的样品进行表征,考察煅烧温度、掺铅量等影响因素。以甲基橙溶液为模拟污染物,30 W紫外灯为光源,考察了铅-二氧化钛薄膜的光催化活性。研究结果表明,掺杂适量的铅离子可以促进二氧化钛锐钛矿相含量的增加及晶粒尺寸的减小;随着煅烧温度的升高,铅-二氧化钛的结晶度提高,复合薄膜表面的二氧化钛颗粒形貌逐渐变为规则形状。当煅烧温度为600 ℃、铅质量分数为0.3%时,复合薄膜具有较好的光催化活性。     

Epitaxial,electro-optically active barium titanate thin films on silicon by chemical solution deposition

Recent progress in the integration of BaTiO₃ thin films with silicon has shown great promise for the development of on-chip photonic devices. However, the highest performing thin films in the literature are deposited by costly and/or complex vacuum techniques. In this study, epitaxial BaTiO₃ thin films are deposited on thin SrTiO₃ template layers on Si(001) from an alkoxide-based chemical solution under atmospheric conditions and yield an effective Pockels coefficient of 27 ± 4 pm/V for an ~85 nm film. Film crystallinity, microstructure, and defect nature are examined by X-ray diffraction and high-resolution transmission and scanning electron microscopy techniques and discussed within the context of the growth method as well as the observed electro-optical response.     

Composition and annealing effects on the linear electro-optic response of solution-deposited barium strontium titanate

Chemical solution deposition was used to deposit epitaxial Ba_xSr_(1−x)TiO₃ thin films on SrTiO₃ template layers on Si(001) for x = 1.0, 0.7, 0.5, 0.3, and 0.0. Effective Pockels coefficients were determined as a function of film composition both for as-deposited films (crystallized at 600°C) and for the films after annealing at 750°C for 10 hours. Pockels response decreased monotonically with decreasing Ba content and coefficients were higher for annealed films, reaching 89 ± 3 pm/V for annealed BaTiO₃. These results are contextualized with the aid of X-ray diffraction and high-resolution transmission microscopy, which illuminated the crystallinity and defect nature of the films.     

Effect of lead content on the performance of niobium‐doped {100} textured lead zirconate titanate films

Niobium‐doped, {100} textured, gradient‐free, lead zirconate titanate (PZT) films were fabricated from solutions with different lead contents. Film lead content was controlled through changes in the average solution lead excess from 14.7% to 17 at.%. The low field dielectric response as well as the polarization‐electric field hysteresis loops were not a strong function of lead content. However, films with lower lead contents in the precursor tended to withstand higher poling fields than films prepared from more lead‐rich precursors. Although no residual PbO was observed at the grain boundaries, films prepared from more lead‐rich solutions had higher levels of grain‐boundary porosity, lower breakdown strengths, and lower threshold electric fields at which cracking was observed.     

锆钛酸锶的烧结及其介电性能表征

以四氯化钛、氧氯化锆、硝酸锶和氢氧化钠为原料,采用共沉淀法在25℃反应90℃陈化2h制备了锆钛酸锶(SrTixZr1-xO3)粉体,用X射线衍射(XRD)表征了锆钛酸锶粉体的物相.用透射电子显微镜表征了锆钛酸锶粉体的粒径.并采用干压成型法压制素坯进行烧结;确定了烧结制度为:升温速率3℃/min,1 400℃保温4h.对烧结后的陶瓷坯体进行介电性能表征,在1 kHz下SrTio.7 Zr0 3 O3陶瓷坯体的相对介电常数为135.6,介电损耗tanδ为24.4×10-3;SrTi0 5 Zro.5 O3陶瓷坯体的相对介电常数为122.3,介电损耗tanδ为137.38×10-3.     

Origin of low dielectric loss and giant dielectric response in (Nb+Al) co‐doped strontium titanate

(Nb+Al) co‐doped SrTiO₃ ceramics with a nominal composition of Sr(Nb_0.5Al_0.5)_xTi_1‐xO₃ (x = 0, 0.02, 0.04, and 0.06) were fabricated using the conventional solid‐state reaction method; giant permittivity (10500) and low dielectric loss (0.03) were obtained at x = 0.06. Dielectric and impedance spectroscopy, X‐ray photoelectron spectroscopy, and Raman spectroscopy, were employed to study why the dielectric property improved. The results indicate that the giant dielectric response occurs because of the combined effects of the off‐center Ti³⁺ reorientation and conduction of electrons with the polar ordering structure Ti³⁺/Ti⁴⁺. In contrast, the low dielectric loss can be attributed to electron localization that occurs because of the defect dipole . These fundamental understandings will benefit the design of doped SrTiO₃ ceramics with desired performance.     

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.     

Effect of strontium doping on structural and dielectric behaviour of barium titanate nanoceramics

ABSTRACT

Barium strontium titanate (Ba_(1?x)Sr_xTiO₃ where, x?=?0.0, 0.2, 0.3, 0.4 and 0.5) nanoparticles have been successfully synthesised by sol–gel method and characterised thoroughly. With the increase in Sr concentration (x?>?0.3), the symmetry of the crystal structure changed from tetragonal to cubic phase. The dielectric behaviour of the ceramic nanoparticles was evaluated using impedance analyser with an operating frequency of 1?Hz to 1?MHz. A very high dielectric constant 4915 was obtained for Ba_0.7Sr_0.3TiO₃ at 1?Hz frequency with low dielectric loss of 1.91, which showed very good value than the one previously reported. The density of the material was found to be >98% of theoretical density. Dielectric constants were measured by varying the temperature from 35 to 150°C and the Curie temperatures were also evaluated. The small amount of Sr doping was beneficial for obtaining high dielectric constant material which can be used in various electronic applications.     

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.     

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.