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

为了研制具有极高介电常数的阻挡层（BL）电容器，已经进行了初步的实验，其中使用了金属导电材料（BaPbO_3）和铁电材料（BaTiO_2、Pb（Fe，W）O_3等，它们被添加以形成绝缘晶界相）。本研究所进行的部分实验和所获得的结果如下：1）BaPbO_3和TiO_2粉末之间的固相反应：BaTiO_3和PbTiO_3是在800 ℃以上通过固相反应生成的，并经X射线衍射证实。2）BaPbO_3与TiO_2陶瓷的连接及反应层的物相分析：BaPbO_3和TiO_2陶瓷在1000 ℃空气中进行了热连接。结果表明，在两种陶瓷的结合界面上，BaTiO_3和PbTiO_3是并排的，呈层状结构。3）添加剂对BaPbO_3陶瓷晶粒结构的影响：在BaPbO_3中添加20多种氧化物，考察它们对BaPbO_3烧结体晶粒结构的影响。4）SrTiO_3-Pb（Fe，W）O_3 BL电容器的制备：采用SrTiO_3-Pb（Fe_<2/3>W_<1/3>）O_3系统成功地制备了具有高介电性能的BL电容器。材料的典型介电常数和tan分别为1.5 × 10^5和5%。可以说，可以生产具有大大改善的介电性质的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.