Microstructure, electrical and dielectric properties, and aging behavior of ZPCCA varistor ceramics with Er2O3 doping

The microstructure, electrical and dielectric properties, and DC-accelerated aging of the ZPCCA (ZnO-Pr6O11-CoO-Cr2O3-Al2O3) ceramics were investigated with various contents of Er2O3. The ceramic phases consisted of a bulk phase of ZnO grains, and a minor secondary phase of mixture of Pr6O11 and Er2O3. The increase of the content of doped Er2O3 increased the densities of sintered pellet from 5.66 to 5.85 g/cm3, and decreased the average grain size from 9.6 to 6.3 μm. With the increase of the content of doped Er2O3, the breakdown field increased from 2390 to 4530 V/cm, and the nonlinear coefficient increased from 28.4 to 39.1. The sample doped with 0.25 mol.% Er2O3 exhibited the strongest electrical stability; variation rates for the breakdown field measured at 1.0 mA/cm2, and for the non-ohmic coefficient were −3.4% and −23.8%, respectively, after application of a stress of 0.95 EB/125 °C/24 h.

Behavior of leakage current characteristics of the varistor samples during application of a stress with various contents of doped Er2O3; 1st: 0.85 EB/115°C/24 h, 2nd: 0.90 EB/ 120°C/24 h, 3rd: 0.95 EB/125°C/24 hFigure optionsDownload as PowerPoint slide