Wrapped Preparation Of Batio <sub> 3 </ Sub>-based Semiconductor Ceramic Capacitor

The electrical properties of the surface layer ceramic capacitor of Y5V based BaTiO₃ synthesized with coprecititation first doped with Nd³⁺ with different concentration (0.030 to 0.065) were investigated.The way of special coprecititation was adopted, the principle as follows:+2NH₄Cl+CO₂↑ +H₂Ot +3H₂OBaCl₂ reacts with NH₄HCO₃ to make BaCO₃, BaCO₃ wraps around TiO₂ particles as nucleus. Rear earth ions were first doped, so this way is heterogeneous coprecititation. The reaction products react to produce salt titanate when it is calcined.The powder was calcined at 1160℃, the granularity is about 2-5μm by the laser granularity analyzing, the granularity distribution is centralized. The ceramic pieces was made as the size of diameter 10mm and the thickness lmm. The powder and the pieces are all tetragonal phase. The lattice parameter is varied with the different doping elements;the 111 and 200 faces have obvious lattice tropism.The ceramic pieces were sintered at different temperature and heat preserved for different hours, It is found that it is the best condition sintered at 1360°C and heat preserved for 3 hours. The ceramic is insulating behavior and its dielectric constant ε is greatly increased doping with high concentration of Nd³⁺. A corresponding increase in the ε, decrease in the courier temperature T_c and insulating waste tan 6 of the latent ceramic With the increase of Nd³⁺concentration at the range of 0.030-0.055;Inflexion appears at the 0.055-0.060 of the concentration of Nd³⁺. Contrasting the samples of Ba_1-xNd_xTiO₃ to Ba_1-3/2xNd_xTiO₃, the electrical properties of the samples of the Ba_1-3x/2Nd_xTiO₃ is better than those of Ba_1-xNd_xTiO₃ because the samples of Ba_1-3x/2Nd_xTiO₃ is electrovalence equilibrium. The ε increase greatly and the T_c decrease together with Zr⁴⁺. It has little influence on the electrical properties with MnCO₃ in the BaTiO₃ ceramic. The electricalproperties of ceramic capacitor based BaTiC^ synthesized with coprecititation first doping with Nd3+ with Sm3+ or Er3+ with different concentration (0.040 to 0.050) were investigated. The e decrease greatly and the Tc increase doped with Sm3+ or Er3+. It is the best when the concentration is 25% of Sm3+or Er+. After the ceramic pieces being reducted-reoxidated, the electrical properties of ceramic capacitor doping with only Nd3+ is not ideal because the materials has not enough anti-reduction. The electrical properties of ceramic capacitor doping together with Zr4+ become better much and the insulating resistance R reach 500MQ, it is showed that ceramic has some anti-reduction. The insulating resistance R reach more than 1000M Q of the ceramic doping together with Mn2+, it showed that Mn2+ had great anti-reduction. The latent dielectric constant e of the ceramic doping with two donors is about 3000 but the insulating resistance R can reach more than 500M Q. The reason is that crystal state of the materials become better, it can improve the quality of the insulation layer when the granularity of the powder become smaller. In generally, the crystal grain need more grow up if we want dielectric constant bigger, but the density of the ceramic can increase and the thickness the insulation layer can become more thin if the crystal grain become smaller, this is equal to increase the dielectric constant to make the electrical properties of ceramic become better. The experiments results just match our intention.Eventually , using the special wrapping way, the electrical properties of the ceramic can reach: The insulating resistance can reach more than 1000M Q, the ratio capacitance C/S = 0.5498 uf/cm2, tan 6 ( x 10"4) less than 400. Our experiments established the foundation of industry applying. This way can be used not only in other II ceramic but also the ceramic capacitor based SrTiC>3 besides surface layer ceramic capacitor based BaTiC>3, So the success of this way has great significance.