Influence of Rare Earth on the Electrical Properties and Microstructure of Barium Titanate Ceramics
The ceramic samples of BaTiO3+½xLn2O3+2mol%TiO2 (0.001≤x≤0.01) were prepared, where Ln is Y, Dy, Ho, Er or Y. The influence of rare earth on the resistivity and microstructure of the samples was investigated by the means of XRD, SEM and electric properties testing. The results showed that the resistivity of La-doped sample decreases when x= 0.003 compared with the undoped sample. However, the range of dopant concentration with Dy, Ho, Er or Y for semiconducting samples is wider, especially for Y-doping. Minimum resistivity at room temperature was observed when x=0.003, which is named after the critical concentration. The experimental results indicated that below the critical concentration of Dy, Ho, Er or Y, the substitution took place in the barium sublattice with electronic compensation, and the rare earth ions began to substitute for titanium gradually above the critical concentration. For Ho-doped BaTiO3 ceramic, the resistivity jump (PTCR effect) near the Curie temperature was the highest in the case of x=0.003. Fine-grained structure of the sample doped with 0.6mol% Dy led to the increase of breakdown field strength and dielectric constant of ceramic samples.
Wei Pan and Jianghong Gong
W. H. Yang et al., "Influence of Rare Earth on the Electrical Properties and Microstructure of Barium Titanate Ceramics", Key Engineering Materials, Vols. 368-372, pp. 465-468, 2008