Effect of La2O3 and CeO2 on Nb2O5 Doped TiO2 Ceramic Varistors
The influence of La2O3 and CeO2 on a new class of polystalline ceramics with electrical properties based on TiO2 was investigated. The content of added La and Ce is in 1 at%, while that of the other addition is always maintained at a constant value. The disks were sintered at 13800C for 4 hours. La2O3 was found to precipitate at the grain boundaries, probably inducing electronic interface states that can trap charges at the TiO2-TiO2 interface and lead to significantly increase the nonlinear behavior. The values for α (» 4.2) and V1mA(» 26 V) support that finding. It was found CeO2 that as a dopant did not strongly influence the nonlinear values of the systems as did La2O3, indicating that it could have formed a solid-state solution with TiO2 in the grains, but did not segregate sufficiently at the grain boundaries. In present work, impedance analyzer, X-ray spectrometer, and scanning electron microscope (SEM) were used.
Wei Pan, Jianghong Gong, Chang-Chun Ge and Jing-Feng Li
J. Mi et al., "Effect of La2O3 and CeO2 on Nb2O5 Doped TiO2 Ceramic Varistors", Key Engineering Materials, Vols. 280-283, pp. 301-304, 2005