【作者】 张素芳；

【导师】 翟学良；

【作者基本信息】 河北师范大学 ， 无机化学， 2003， 硕士

【摘要】 钛酸铅是一种典型的铁电材料，因为它居里点高、介电常数小、机电各向异性大，很适合应用于高温高频领域。但由于其四方矫顽场大，成为陶瓷的晶界能高，使它在退火过程中经过居里点时，容易产生微裂纹，而使其应用受限。为了解决这一问题，科研工作者进行了各种各样的探索：(1)对液相合成方法的研究，目的在于获得结晶良好的粉体原料，以降低内应力；(2)采用固相法合成粉体原料，掺杂后研究其物理性能。所以我们选择钛酸铅系电子陶瓷粉体的水热合成和陶瓷的电学性质作为本论文的研究内容。与其他方法相比，水热法不需要高温煅烧，在533K或更低的温度下就可获得各种陶瓷材料，就钛酸铅而言，这么低的温度不仅可以降低在煅烧和球磨过程中杂质的引入，还可以减少铅的挥发。 本论文的主要内容如下： 一、文献综述 总结了钛酸铅系电子陶瓷及粉体的制备方法，比较了各种方法的优缺点；叙述了电子陶瓷的电性能如：压电性、热释电性和铁电性，探讨了铁电性产生的机理；简单介绍了钛酸铅系电子陶瓷的应用。 二、纯钛酸铅电子陶瓷的制备及其电性能研究 采用水热法制备了纯钛酸铅纳米晶，考察了多种水热条件：反应物浓度、水热温度和时间、介质碱度和铅钛比等对钛酸铅粉体微观形貌和晶体结构的影响，分析了这些水热条件的影响机理，找到了较好的纯钛酸铅的水热合成条件。目前我们基本上可以通过控制水热条件得到不同粒径的钛酸铅粉体，为今后研究钛酸铅陶瓷的晶粒尺寸效应奠定了基础。 采用传统方法制得了纯钛酸铅陶瓷，考察了多种影响因素：压片压力、烧结温度、烧结时间和烧结氛围等对钛酸铅陶瓷微观形貌和晶体结构的影响，找到了较为适宜的制陶条件。 测量了室温下纯钛酸铅陶瓷的介电频谱。 三、掺杂钛酸铅陶瓷的制备及其电性能研究 在由纯钛酸铅确定的较佳的水热条件下，合成了一系列掺杂钛酸铅粉体，掺杂方式包括A位和B位。其中A位包括等价掺杂和施主掺杂，等价掺杂采用碱土金属(饭、sr、Ba:施主掺杂采用稀土金属La、Sm。B位采用Zr。并且考察了这些元素的掺入量对钦酸铅粉体微观形貌和晶体结构的影响，我们发现杂质元素的掺入会引起钦酸铅粉体粒径和四方性的改变，元素不同影响不同。在由纯钦酸铅确定的较为适宜的制陶条件下，分别制得了上述元素掺杂钦酸铅陶瓷，讨论了它们的掺入量对钦酸铅陶瓷微观形貌和晶体结构的影响。 最后分别测量了室温下掺杂钦酸铅陶瓷的介电频谱，实验表明悯、衫、钙、银、钡、错的掺入对钦酸铅陶瓷的介电常数和介电损耗均有不同程度的影响。更多还原

【Abstract】 Compared with other ferroelectronic materials, lead titanate (PbTi03) has many useful properties, including a high transition temperature (-763K), a low ratio for the planar-to-thickness coupling factor, a low aging rate of the dielectric constant, and low dielectric constant. Therefore, PbTi03 shows great promise as a stable pyroelectric and piezoeletric materials for high-temperature or high-frequency applications.The advantage of hydrothermal processing is that many crystalline ceramic materials may be synthesized without a calcination step at temperature of 533K and lower. In the case of PbTi03, such low processing temperature eliminate volatilization, in addition to minimizing impurities associated with calcination and ball-milling steps.The main points:I . ReviewIn this part we have not only summarized the preparation methods of Lead-based titanate powders and ceramics, but also discussed the properties and application of the ceramics.II. Preparation and electric properties of lead titanate ceramics1. PbTi03 powders have been synthesized by suspending Ti(OC4H9)4 in aqueous solution of NaOH and Pb(COOCH3)2 3H20 at temperature ranging from 473K to 533K. Experiments show that the growth and morphology of hydrothermally derived lead titanate powders will depend strongly on the feedstock concentration, reaction time and temperature, NaOH concentration, and [Pb]/[Ti] ratio.2. PbTi03 ceramics were prepared by conventional sintering method. The effect of sinter time, temperature and atmosphere on their growth and morphology has been examined.3. The dielectric spectrum of PbTi03 ceramics has been carried out using HP4194A.III. Preparation and electric properties of modified lead titanate ceramics1. We have obtained La, Sm, Ca, Sr, Ba, and Zr-doped lead titanate powders and ceramics under the same conditions as fine PbTiO3. The influence of dopants on the size and morphology of PbTiO3 powders and ceramics has been investigated.2. The dielectric spectra of modified PbTiO3 ceramics have been measured by HP4194A. The results indicate that the dopants will change the dielectric constant and tg 8 of PbTiO3.更多还原