Investigation of the Solid State Reaction between Metallic conducting and Ferroelectric Ceramics for the Development of Materials with Extremely High Dielectric Constants

利用金属导电材料（BaPbO_3）和铁电材料（BaTiO_2、Pb(Fe，W)O_3等，加入形成绝缘晶界相）制备具有极高介电常数的阻挡层（BL）电容器进行了初步实验。本研究中所进行的部分实验和得到的结果如下：1)BaPbO_3与TiO_2粉末之间的固相反应：在800℃以上通过固相反应生成BaTiO_3和PbTiO_3，并通过x射线衍射证实了这一点。2) BaPbO_3与TiO_2陶瓷的连接及反应层的物相分析：BaPbO_3与TiO_2陶瓷在1000℃空气中热连接。结果表明，BaTiO_3和PbTiO_3在两种陶瓷的界面上形成了一层又一层（并排）的结构。x射线微量分析证实了这一点。3)添加剂对BaPbO_3陶瓷晶粒结构的影响：在BaPbO_3中加入20多种氧化物，考察其对BaPbO3烧结体晶粒结构的影响。结果表明，ZnO、CuO和NiO的加入能有效地制备出制备BL电容器所需的大晶粒材料。4) SrTiO_3-Pb(Fe，W)O_3 BL电容器的制备：利用SrTiO_3-Pb(Fe_<2/3>W_<1/3>)O_3体系成功制备了具有高性能介电性能的BL电容器。材料的典型介电常数为1.5 × 10^5， tan为5%。可以说，可以生产出介电性能大大改善的BL电容器。

Preliminary experiments have been made in attempt to develop barrier-layer (BL) capacitors with an extremely high dielectric constant by using a metallic conducting material (BaPbO_3) and ferroelectric materials (BaTiO_2, Pb(Fe,W)O_3, and so on, which are added to form insulating grain boundary phases). Some of the experiments carried out in this study and the ob-tained results may by described as follows:1) Solid state reaction between BaPbO_3 and TiO_2 powders: The formation of BaTiO_3 and PbTiO_3 occurred above about 800 C through the solid state reaction, and it was confirmed by X-ray diffractometry.2) Joining of BaPbO_3 with TiO_2 ceramics and phase analysis of the reaction layers: BaPbO_3 and TiO_2 ceramics were thermally joined at 1000 C in air. It has been found that BaTiO_3 and PbTiO_3 were formed layer upon layer (side by side) at the interface between the two ceramics joined. This was confirmed by XMA (X-ray microanalysis).3) Effect of additives on the grain structure of BaPbO_3 ceramics: More than twenty kinds of oxides were added in BaPbO_3 to examine their influences on the grain structure of BaPbO3 sintered bodies. The additions of ZnO, CuO and NiO were found to be effective to produce the materials with large grains grown favorite for making BL capacitors.4) Preparation of SrTiO3-Pb(Fe,W)O_3 BL capacitors: BL capacitors with a high performance dielectric property have been successfully prepared using the SrTiO_3-Pb(Fe_<2/3>W_<1/3>)O_3 system. The typical dielectric constant and tan of the materials were found to be 1.5x10^5 and 5%, respectively. It may be possible to say that BL capacitors with much improved dielectric properties can be produced.