液相法制备钛酸铅粉的研究

研究了反应温度、酸碱度、放置时间和煅烧温度对化学共沉淀法法制得的钛酸锶铅粉末的影响,探讨了其热分解过程,用ＸＲＤ、ＳＥＭ、ＤＴＡ和ＥＰＭＡ对粉体进行了综合分析,得到了度较高的钛酸锶铅粉末。     

改进草酸盐共沉淀法制备钛酸锶钡粉体

以硝酸钡、硝酸锶、草酸和钛酸丁酯为原料,通过向锶钡盐溶液中预先添加适量氨水,采用草酸盐共沉淀法制备了草酸氧钛锶钡[Ba0.6Sr0.4TiO(C<2O4)2·4H2O,BSTO]前躯体粉体,将该前躯体800℃煅烧4h得到钛酸锶钡(Ba<0.6Sr0.4TiO3,BST)粉体.改进的工艺省去了在共沉淀同时添加NH3·H2O调节反应体系pH值的过程,使整个工艺方法较之传统工艺更具可操作性.用X射线衍射仪和扫描电镜研究了BST粉体的相组成和微观形貌,并对该工艺所得BST粉体形貌形成机理进行了探讨.结果表明:所制备的BST粉体为高纯立方晶相,粉体呈准球状,粒径为1～2 μm,其比表面积达到18.52 m2/g;BST粉体的"菜花"状软团聚形貌是由于单颗粒BSTO粉体高温煅烧发生分解放出气体而形成.     

钛酸锶粉体合成新方法研究

以四氯化钛和氯化锶为原料，碳酸铵和氨水作沉淀剂化学共沉淀法合成钛酸锶粉体，研究了工艺条件对产品纯度和锶钛比的影响，最佳反应条件为：氯化锶与四氯化钛摩尔比为1．02，碳酸铵与氯化锶摩尔比为1．40，反应温度为室温，反应时间4h,pH=10，煅烧温度900℃，煅烧时间4h，所得产品经化学，红外光谱，电镜，X－射线衍射和原子发射光谱分析，分析结果显示：产品纯度高，粒径小，锶钛化合适。     

纳米钛酸锶制备的研究现状及展望

简要地叙述了钛酸锶及钛酸锶纳米功能材料的性能及应用价值概况,讨论了目前钛酸锶超细粉体的各种制备方法及其优缺点,采用机械化学法实现了低温合成,得到的粉体粒度细纯度高,是一种很有发展前景的钛酸锶超细粉体的制备方法.     

纳米钛酸锶粉体的溶胶—凝胶法制备与研究

以硝酸锶和钛酸丁酯为原料,柠檬酸为络合剂,乙二醇为稳定剂,在液相中发生络合反应制备前驱物,再将前驱物干燥,烧结得到钛酸锶粉体,并对粉体进行XRD分析。经多组对比试验表明,pH值、用水量、柠檬酸用量对粉体的性质有比较明显的影响。     

混合碱法制备钛酸锶钡纳米陶瓷粉体的研究

本文以熔融的无水混合碱作为溶剂,以成本低廉的金属无机盐和氧化物作为反应物,成功制备了钛酸锶钡纳米陶瓷粉体.用XRD、SEM对粉体进行了表征.研究结果表明,在温度200℃,加热24h时生成钛酸锶钡(Ba0.77 Sr0.23 TiO3)粉体,在温度245℃,加热24h生成钛酸锶钡(Ba0.6 Sr0.4 TiO3),合成产物为四方形,粉体的粒径为60～120nm,粒度分布均匀.     

溶胶-凝胶法制备钛酸锶粉体及其光催化性能的研究

用溶胶-凝胶法制备钙钛矿型SrTiO₃粉体。并用自制的反应器,考察了SrTiO₃粉体对NOx的光催化脱除能力,研究了光源、气体初始浓度、湿度对光催化效果的影响。结果表明,经过45 min的光催化反应,不同浓度的气体中NOx的脱除率均在70%以上。     

钛酸锶铅基陶瓷材料的半导化研究

研究了（Ｓｒ０．４８Ｐｂ０．４８Ｙ０．０３Ｃａ０．０１）ＴｉＯ３基陶瓷的半导化行为。结果表明：ＰｂＯ适当过量有利于半导化。Ｒａｍａｎ光谱，ＡＥＳ分析表明，随着ＳｉＯ２含量的增量，氧空位浓度及Ｔｉ＾３＋浓度增大，ＸＲＤ分析表明，随ＳｉＯ２含量增大，轴比ｃ／ａ增大。     

液相原料制备PTC粉体及其性能研究

本文介绍了一种通过液相原料形式引入以草酸盐共沉淀来制备ＰＴＣ粉体的新方法。即ＢａＴｉＯ３、Ａｌ２Ｏ３、ＳｉＯ２、ＭｎＯ２、Ｙ２Ｏ３等均采用液相原料引入,然后用草酸进行共沉淀,通过灼烧制得ＰＴＣ粉体。用这种粉体制得的ＰＴＣ陶瓷,其晶粒均匀性和电性能都优于传统固相法制得的ＰＴＣ陶瓷。     

单相钛酸锶粉体的制备研究

采用SEM、XRD及FT-IR研究了碳酸锶和二氧化钛(锐钛矿)经高能球磨后的结构变化,讨论了单相钛酸锶的形成机理.SEM和XRD研究表明,高能球磨破坏了原料的晶体结构,使得其比表面积和无序程度增加;FT-IR研究表明,高能球磨使原料的键能减小.可见,高能球磨导致了原料内部贮能增加和反应活化能减小.球磨40 h的原料在900 ℃煅烧2 h可以得到单相钛酸锶,而未粉磨的需要1300 ℃.     

Phase Stability and Ferroelectric Properties of Lead Strontium Zirconate Titanate Ceramics

The effect of compositional modifications on the field-induced phase-transition behavior and dielectric properties of strontium-doped lead zirconate titanate (PZT) ceramics was studied. PZT compositions with different strontium and titanium contents, within the general formula Pb_{1– x} Sr _x (Zr_{1– y} Ti _y )O₃ and located in the tetragonal antiferroelectric (AFE) and rhombohedral ferroelectric (FE) phase fields were prepared by tape casting and sintering. X-ray diffraction and polarization measurements were used to locate compositions suitable for investigation of the field-induced AFE–FE phase transition. The results indicated that a higher Sr²⁺ content decreased the polarization and hysteresis and increased the switching field; a lower Ti⁴⁺ content decreased the polarization and increased the switching field and hysteresis. A high room-temperature dielectric constant was obtained for compositions near the phase boundary. These results suggest that a combination of both A -site and B -site modifications can be used to tailor ferroelectric properties, such as the switching field and hysteresis, of these strontium-doped PZTs displaying a field-induced AFE–FE phase transition.     

Crystallization of Lead Titanate Prepared by Wet Chemical Methods

The crystallization behavior of PbTiO₃ powder prepared by sol-gel and coprecipitation techniques was investigated by DTA, XRD, and Raman spectral analyses. PbTiO₃ precursor powders were derived from a mixed solution of Pb(NO₃)₂ and TiCl₄ at 40^o to 43^oC and pH of 9.0 to 9.7. The dried gel and coprecipitated powders are both amorphous but have different structures. The room-temperature Raman spectra from heat-treated powders changed continuously from an amorphous to a crystalline state with increasing annealing temperature. By annealing coprecipitated powders, a dramatic change in the Raman spectra, caused by the structural relaxation as the annealing temperatures increased, was clearly visible, i.e., coprecipitated, gel, and crystalline structure, in turn.     

Topotatic-Like Phase Transformation of Amorphous Lead Titanate to Cubic Lead Titanate

The crystallization process of lead titanate (PT) prepared using the polymeric precursor method was investigated using X-ray diffractometry, Raman spectroscopy, electron microscopy, and X-ray absorption spectroscopy techniques. The results showed that amorphous PT was formed by an O–Ti–O structure composed of fivefold and sixfold oxygen-coordinated titanium. The local structure of the amorphous PT phase was similar to that of the cubic PT phase, i.e., similar coordination number and similar bond lengths, leading to a topotactic-like transformation during the phase transformation from amorphous to cubic perovskite PT. Because of the low crystallization temperature, every transformation observed during the crystallization process was associated with a short-range rearrangement process.     

Fabrication of NiO Nanoparticle-Coated Lead Zirconate Titanate Powders by the Heterogeneous Precipitation Method

NiO nanoparticle-coated lead zirconate titanate (PZT) powders are successfully fabricated by the heterogeneous precipitation method using PZT, Ni(NO₃)₂·6H₂O, and NH₄HCO₃ as the starting materials. The amorphous NiCO₃·2Ni(OH)₂·2H₂O are uniformly coated on the surface of PZT particles. XRD analysis and the selected-area diffraction (SAD) pattern indicate that the amorphous coating layer is crystallized to NiO after being calcined at 400°C for 2 h. TEM images show that the NiO particles of ∼8 nm are spherical and weakly agglomerated. The thickness of the nanocrystalline NiO coating layer on the surface of PZT particle is ∼30 nm.     

Preparation of Lead Zirconate by Homogeneous Precipitation and Calcination

Antiferroelectric PbZrO₃ has been synthesized by homogeneous precipitation from aqueous solutions in the presence of urea (NH₂CONH₂) and calcination for 6 h at 700°C. SEM studies displayed the presence of submicrometer powder, with a significant degree of agglomeration.     

Polymorphic Phase Transformation of Lead Monoxide and Its Influence on Lead Zirconate Titanate Formation

The polymorphic phase transformation of PbO from massicot to litharge phase is easily produced by mechanical force. The transformation is relatively quick by wet ball-milling. The additions of TiO₂ and ZrO₂ tend to retard it. A second-order exponential relation is observed between the fractional conversion and the milling time for pure PbO, PbO-TiO₂, and PbO-ZrO₂-TiO₂ systems with a rutile constituent. This exponential relation is changed into a first-order logarithmic relation when anatase instead of rutile is used. Although the PbO _ss phase is observed irrespective of the phase of the PbO in the raw materials, this PbO _ss peak is more obvious when massicot PbO or anatase TiO₂ is used. The formation of PbO _ss phase is also dependent on the reactivity of the ZrO₂, and its presence can affect the formation and piezoelectric properties of PZT ceramics.     

BST铁电薄膜的制备、应用及其研究进展

综述了钛酸锶钡（BST）铁电薄膜的4种制备工艺：磁控溅射（Magnetron sputtering）法、金属有机物化学气相沉积（MOCVD）法、脉冲激光淀积（PLD）法,以及溶胶-凝胶（Sol-Gel）法.并介绍了BST铁电薄膜在动态随机存储器、非致冷红外探测器热成像、移相器等方面的应用及其研究进展.     

钛酸铋压电陶瓷厚膜的制备

以五水硝酸铋草酸和钛酸四丁酯为原料,采用化学共沉淀法,制得钛酸铋（BIT）粉体。然后﹑采用多层晶粒生长法,通过丝网印刷制得BIT压电陶瓷厚膜。借助XRD和SEM对产物晶体结构进行表征,并研究烧结温度对取向度的影响。结果表明,650 oC煅烧2 h可获得单一晶相的BIT粉体,经球磨后得到粒径小于1μm纳米粉体。1200 oC,升温速率10 oC/min,保温2 h时烧结的BIT厚膜在（00k）方向上取向度最高,达到95.50%。