【作者】 曹丽凤；

【导师】 李玲霞；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2010， 博士

【摘要】 基于目前Ag(Nb 1-x Ta x )O3体系的研究动态,本论文分别采用固相法与液相法(溶胶-凝胶法)制备了Ag(Nb 1-x Ta x )O 3陶瓷,对Ag(Nb 1-x Ta x)O3体系进行了掺杂改性研究,研制出介电性能优良的陶瓷体系。并根据电介质理论、烧结理论及晶格振动等理论深入分析了影响体系介电性能的微观机制。在固相法制备Ag(Nb 1-x Ta x )O 3体系方面,主要的研究工作如下:(1)成功合成了Ag(Nb1-xTax)O(3x=0.1~0.5)晶相,确定了制备Ag(Nb 1-x Ta x )O3体系的热处理工艺。系统研究了体系的微观结构与介电性能,探讨了体系因Ta含量不同,介电性能存在较大差异的本质原因,为体系介电性能的改性打下了一定的基础。(2)通过对添加剂掺杂改性Ag(Nb 1-x Ta x )O3的研究,成功研制出超高介(ε>1000)、低损耗的Ag(Nb 0.8 Ta 0.2 )O 3 -CaF2体系。并将Raman光谱测试技术引入该体系的研究中,建立了体系微观机制中晶格振动模式的振动特性与介电性能之间的联系,完善了Ag(Nb 1-x Ta x )O 3体系介电性能的改性理论。(3)对单一氧化物、复合氧化物以及稀土元素掺杂改性Ag(Nb 1-x Ta x )O3基陶瓷体系进行了系统研究,探讨了不同组分氧化物对体系掺杂改性的微观机制,成功研制出介电性能优良的ANT82-4.5wt%Bi 2 O 3陶瓷体系。在溶胶-凝胶法制备Ag(Nb 1-x Ta x )O 3体系方面,主要的研究工作如下:(1)在溶胶-凝胶法制备工艺中,目前大都采用强腐蚀性的氢氟酸或硝酸,将五氧化二铌、五氧化二钽转化为中间产物氟络合物,进而制备Ag-Nb-Ta溶胶,此方法对周围环境及人体健康造成了极大的危害。本论文提出了一种新的工艺路线,即改用安全型的碱金属盐,通过合成铌(钽)酸盐成功制得了该体系溶胶。(2)目前,利用溶胶-凝胶法合成Ag(Nb 1-x Ta x )O3纳米粉体的研究少有报道,本文系统研究了工艺参数对溶胶稳定性及纳米粉体微观结构的影响,并制备出介电性能优良的Ag(Nb 1-x Ta x )O3陶瓷。溶胶-凝胶法实现了分子乃至原子尺度上的均匀混合,为进行材料组分、结构与性能设计奠定了基础。(3)分别采用固相法与溶胶-凝胶法制备出Ag(Nb 0.6 Ta 0.4 )O3陶瓷,首次发现在两种不同方法制备的该陶瓷体系中,其介电常数温度特性存在截然不同的变化规律。对导致陶瓷体系这一不同变化规律的微观机制进行了探讨,建立了晶格畸变、界面张力等微观结构与介电特性之间的关系,为材料结构与性能的设计、合成研究奠定了理论与实验基础。更多还原

【Abstract】 Based on the research trends, the Ag(Nb 1-x Ta x )O3 ceramics were prepared by the solid-state method and liquid phase method (sol-gel method) in this work. The dielectric properties of the ceramics doped with dopants were investigated. In addition, the micromechanisms influencing the dielectric properties of the ceramics were analyzed according to the dielectrics theory, sintering theory and lattice vibration theory.For the solid-state preparation of Ag(Nb 1-x Ta x )O3 ceramics, the main researches were shown as follows:(1) The main phase of Ag(Nb 1-x Ta x )O3(x=0.1~0.5)without any second phases was obtained by the solid-state method, and the heat-processing was determined. The microstructures and dielectric properties of the ceramics were investigated, and the reasons for leading to the different dielectric properties of the ceramics were discussed. These provided the foundation for improving the dielectric properties of the ceramics.(2) The high-performance products of Ag(Nb 0.8 Ta 0.2 )O 3 -CaF2 systems, with ultra high permittivity (ε>1000) and low dielectric loss, were prepared. Meanwhile, Raman testing technology was induced. The relationship between lattice vibration characteristic for the lattice modes and the dielectric properties was established, which completed the modification theory.(3) The dielectric properties of the ceramics doped with single oxide or composite oxides and rare earth elements were investigated. The mechanisms of the different dopants improving the dielectric properties were investigated. The high-performance products of ANT82-4.5wt%Bi 2 O 3 ceramics were obtained.For the sol-gel preparation of Ag(Nb 1-x Ta x )O3 ceramics, the main research works were shown as follows:(1) At the present, for the sol-gel processing techonology, niobium pentaoxide and tantalum pentaoxide were also dissoloved by using the corrosive HF and HNO3, and then the Ag-Nb-Ta precursor sol was prepared. This processing method did harm to the environment and the body health. In this work, a new processing route was proposed. The sol was prepared by using the safety alkali salt, which could dissoloved niobium pentaoxide and tantalum pentaoxide into tantalate and niobate. (2) There were rarely reports for the Ag(Nb1-xTax)O3 nanopowders by using sol-gel method. In this work, the influence of processing parameters on the stability of the sol was invesitigated systematacially. And the high-performance Ag(Nb1-xTax)O3 ceramics were obtained. The uniform mixing for the materials in molecular even atomic level was realized by using the sol-gel method, which lay foundation for the design of material compostion, structure and properties.(3) The Ag(Nb0.6Ta0.4)O3 ceramics prepared by the solid state method and sol-gel method. In this work, the different dielectric temperature characteristics for the Ag(Nb0.6Ta0.4)O3 ceramics was found for the first time. The mechanism leading to the characteristics was discussed. The realationship between lattice distortion and interfacial tension was established, which lay theoretical and experimental foundations for design and synthesis of materials structure and properties.更多还原