【作者】 张文星；

【导师】 曹立新；

【作者基本信息】 中国海洋大学 ， 海洋化学工程与技术， 2013， 博士

【摘要】 钛酸钡（BaTiO₃）电子材料是目前最具研究活力和应用最为广泛的先进材料之一。自从BaTiO₃被发现以来，其已在现代电子材料工业发挥重要作用。随着近年电子器件的高性能化和微型化方向的发展，高介电常数、低损耗，具有介温稳定性、高温稳定性、纳米级晶粒的介电材料愈加受到关注，偏重此方向的研究也越来越多。在此背景下，本文从一元、二元元素掺杂改善BaTiO₃粉末及陶瓷材料的性能入手，以提高介频和介温的稳定性、提高介电常数、降低介电损耗为目标，对BaTiO₃材料的制备及其性能进行了研究。一、获得高活性高纯度粉体是进一步研究对BaTiO₃掺杂的基础。BaTiO₃掺杂的方法虽然种类较多，采用价格低廉的Ba、Ti化合物作为反应前躯体，仍然是经济有效的合成途径。本文采用水热法（溶剂热）研究了不同Ti化合物为钛源对BaTiO₃合成的影响，进一步筛选合理的合成条件。实验证明：以BaCl2、钛酸四丁酯、NaOH作为合成原料在较低温度条件下即可获得纯度高、单分散性好、粒径范围窄、粒径在纳米级并且粒径可调的的粉体。二、采用水热法制备了Nd³⁺掺杂的BaTiO₃，研究了不同掺杂量的Nd³⁺对BaTiO₃粉末和陶瓷介电性能的影响。发现在室温下Nd³⁺含量较低时，BaTiO₃具有较高的介电常数和较低的介电损耗，其介频和介温稳定性有很大提高。随着Nd³⁺浓度的提高，介电常数和介电损耗迅速降低。同时随着Nd³⁺浓度的进一步升高，在高温烧结阶段伴随杂相BaTi₂O₅的出现。通过对不同Ba/Ti比条件下制备的Nd³⁺掺杂的钛酸钡的晶格参数进行分析，认为Nd³⁺在BaTiO₃中是一种A位掺杂剂。三、考虑钛酸锶钡（BST）具有较高的介电常数和较低的相变温度，钛酸锆钡（BZT）则能有效降低居里温度。为有效降低BST陶瓷的相变温度同时改善BZT的介电性能，采用水热（溶剂热法法）制备了Sr²⁺、Zr⁴⁺共掺杂的纳米级BaTiO₃颗粒，探讨了不同掺杂量对BaTiO₃结构与性能的影响。实验发现Zr⁴⁺掺杂的BST（BSZT），能有效地抑制BaTiO₃晶粒的生长，显著降低居里点温度。随着Zr掺杂量的增加，弥散相范围增加，对BST的居里峰有较好的展宽效应，提高了BSZT的介温稳定性。同时分析了Sr²⁺、Zr⁴⁺共掺杂BaTiO₃的溶液反应机制。四、本文分析了Ca²⁺掺杂对BZT陶瓷结构和性能的影响。结果表明Ca²⁺掺杂后的锆钛酸钡（BCZT）陶瓷颗粒的形状由片状逐渐转变为立方体结构。同时随Ca²⁺掺杂量的增加， BCZT陶瓷的弥散相变增强，介温稳定性提高。更多还原

【Abstract】 At present, BaTiO₃is one of the most dynamic and the most widely used advancedceramic materials. Since1940the discovery of BaTiO₃, it has played an important role inmodern ceramic industry. In recent years, the development direction has developed alongmore performance oriented and miniaturization. The dielectric of high dielectric constant,low loss and high-temperature stabilizing shows more attention and expectation andmore research in the field has been developed. Under thus background, this paper beginswith developing performance of BaTiO₃ceramic material doped with different elements.In order to improve dielectric-frequency stability and dielectric-temperature stability, thephysicochemical properties and related mechanisms have been investigated.1. For the preparation of BaTiO₃ceramics with optimum properties, it is necessary toobtain highly active and high purity powder first. The method for the synthesis of dopedBaTiO₃is the variety of ways, it is an effective and economic way with inexpensivecompound of barium and titanate to prepare BaTiO₃. In this paper, the influence onsynthesizing BaTiO₃powders with different titanate precursors has been investigated, theoptimum synthesis conditions was carried out. Experiments indicate that highly pure,monodisperse, narrow diameter distribution, nanometric and size controllable BaTiO₃powder synthesized with hydrothermal method at lower temperature.2. Nd-doped barium titanates were successfully synthesized via a hydrothermal route.The influence of Nd³⁺content on dielectric properties was studied. The results indicatethat Nd doped barium titanate shows high dielectric constant and low dielectric loss, thestability of dielectric properties-frequency and dielectric properties-temperature has a dramatic increase. With the improvement of Nd content, the dielectric constant and thedielectric loss decrease rapidly. The impure phase BaTi₂O₅appeared after high heatsintering with the further improvement of Nd content. Results analysisof lattice parameters of Nd-doped barium titanates reveales that the substituent position ofNd is A site in BaTiO₃.3. Considering the high dielectric constant and low phase transition temperature ofBST, BZT shows a low Curie temperature. In order to decrease the phase transitiontemperature and increase the dielectric properties, Sr and Zr co-doped barium titanate（BSZT） nanoparticles were synthesized by solvothermal method under identicalpreparation conditions of Sr and the effect on microstructure and properties was discussed.The results show that the growth of grains was restrained, the Curie temperaturedecreases and broadened gradually. The degree of diffusion phase transition increaseswith increasing Zr content and the stability of dielectric constant-temperature increases.The reaction mechanisms of BSZT nanoparticles synthesized by solvothermal methodwere analyzed.4. The effect of Ca doped barium zirconate titanate on microstructure and dielectricproperties was investigated. The result shows that the shape changes from laminated sheetto cube，the dielectric loss decrease and the Curie peak becomes broadening in the rangeof temperature measurement and the stability of dielectric constant-temperatureincreases..更多还原