钙离子掺杂对Ba(Fe_(0.5)Nb_(0.5))O_3陶瓷介电性能的影响

Effects of calcium-doping on the dielectric properties of Ba(Fe_(0.5)Nb_(0.5))O_3 ceramics

采用固相法制备Ba_(1-x)Ca_xBa(Fe_(0.5)Nb_(0.5))O_3陶瓷材料,研究了Ca^(2+)掺杂对Ba(Fe_(0.5)Nb_(0.5))O_3陶瓷显微结构及介电性能的影响.在1 200℃煅烧制备出了单一物相的Ba_(1-x)Ca_xBa(Fe_(0.5)Nb_(0.5))O_3(x=0,0.03,0.06,0.12,0.15)粉体,并在1 350℃烧结得到相对密度较高、显微结构致密的BCFN陶瓷.随着Ca^(2+)含量的增加,其晶粒尺寸呈现先减小后增大的趋势,而其介电常数则呈现相反趋势.当x=0.06时,介电常数在1kHz可达到45 000,而其介电损耗在室温1kHz下无明显变化.此外,Ca^(2+)掺杂不仅明显提高了陶瓷的介电常数,且有效提高了其温度稳定性.

The perovskite Ba（1-x）CaxBa（Fe0.5Nb0.5）O3（BCFN）ceramics were prepared by solidstate reaction,and the influence of Ca^2＋doped on the microstructures and dielectric properties of Ba（Fe0.5Nb0.5）O3were investigated.The XRD results indicate that the single phase with cubic perovskite structure of BCFN were all obtained when calcined at 1 200℃,and the dense ceramics were sintered at 1 350 ℃.All the samples are dense and homogenous in microstructure.The average grain size of the ceramics decreased and then enhanced with increasing the content of Ca^2＋,while the dielectric constant tended to opposite.As x=0.06,the dielectric constant of Ba（0.94）Ca（0.06）（Fe0.5Nb0.5）O3can reach 45 000 at 1kHz,meanwhile,the dielectric loss had no obvious difference between pure BFN and BCFN ceramics at room temperature.In addition,not only the higher dielectric constant was obtained in Ba（0.94）Ca（0.06）（Fe0.5Nb0.5）O3ceramics,but also the higher temperature stability can be achieved with Ca^2＋doped.