稀土掺杂对还原烧结钛酸钡陶瓷微结构和电性能的影响  

INFLUENCE OF RARE-EARTH DOPING ON MICROSTRUCTURE AND DIELECTRIC PROPERTIES OF BARIUM TITANATE CERAMICS SINTERED IN REDUCING ATMOSPHERE

作　　者：李波[1] 周晓华[1] 张树人[1] 

机构地区：[1]电子科技大学微电子与固体电子学院,电子薄膜与集成器件国家重点实验室,成都610054

出　　处：《硅酸盐学报》2008年第3期277-282,共6页Journal of The Chinese Ceramic Society

基　　金：电子科技大学青年基金(L08010301JX0727)资助项目

摘　　要：采用固相工艺制备BaTiO3-R2O3-MgO-MnO2(R=La,Ce,Pr,Nd,Sm,Gd,Dy,Ho,Y,Er,Yb)系陶瓷,全面研究了稀土掺杂对还原烧结钛酸钡(BaTiO3)陶瓷微结构和电性能的影响。扫描电镜分析结果显示:小离子半径稀土比大离子半径稀土更有效地改善微观结构,并且随着稀土离子半径的减小,其晶粒抑制作用更加显著。实验发现:大半径稀土掺杂可生成化学均匀性晶粒,得到介电常数-温度(ε-T)单峰曲线,并导致Curie点下降;小半径稀土掺杂可生成壳-芯结构晶粒,获得ε-T双峰曲线,晶粒壳的体积相对膨胀,对晶粒芯产生的张应力作用促使Curie点上升,其平坦的电容变化率-温度(ΔC/C-T)特性满足X8R。随着稀土离子半径的增大,该体系的绝缘电阻率总体呈降低趋势,归因于稀土元素在BaTiO3中取代位及补偿方式的不同。The influence of rare-earth oxides doping on the microstructure and dielectric properties of BaTiO3-R2O3-MgO-MnO2 （R = La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Y, Er, and Yb） system sintered in reducing atmosphere was studied. Scanning electron microscope results show the smaller ions can inhibit grain growth more effectively than the larger ions do. The experiments indicate the lar-ger-ion-doped samples form homogeneous grains, resulting in single-peak of dielectric-temperature （ε-T） curves and a decrease of the Curie point, whereas the smaller-ion-doped ones produce core-shell grains, leading to double-peak ε-T curves and an increase of the Curie point. The shift of the Curie point to higher temperatures is attributed to the tensile stress resulting from the volume-expansion mismatch between the grain core and grain shell. The insulation resistivity decreases with increasing radius of rare-earth ions owing to the different occupation sites and compensation models in BaTiO3. The smaller-ion-doped specimens with flat capacitance variation-temperature （△C/C-T） behavior meet X8R specifications.

关 键 词：钛酸钡 稀土氧化物 CURIE点 壳-芯结构 多层陶瓷电容器 

分 类 号：TM534[电气工程—电器]