Rare earth oxides effects on both the threshold voltage and energy absorption capability of ZnO varistors

Progress on rare-earth doped ZnO-based varistor materials

“…Compared to the undoped one, RE doping can often greatly increase the nonlinear coefficient of ZnO-Pr 6 O 11 -based varistors and reduce their leakage current to certain extent, thus improving the ability of the thermal shock resistance and extending the service life of varistors. (3) The doped RE oxides can act as grain growth inhibitors to ZnO grains during sintering, thus improving the voltage gradient of varistors without reducing their energy absorption capacity; meanwhile, they can also increase the through-current capability and reduce the residual voltage of varistors, finally improving the resistor qualities [8,[10][11][12]. In this review, the progress on RE-doped ZnO-based varistor materials in recent years is summarized.…”

“…RE-doped ZnO varistor materials have the following advantages [8][9][10][11][12]. (1) Compared with the doping by other elements (under the same conditions), RE doping into ZnO varistors can significantly increase the voltage gradient of varistors.…”

Highly nonlinear property and threshold voltage of Sc2O3 doped ZnO-Bi2O3-based varistor ceramics

“…Studies [6,10,11] have revealed that the addition of rare-earth oxides in the starting composition decreases the average grain size, and many reports [12][13][14][15][16] Dy 2 O 3 , on the microstructure and electronic properties of the ZnO-Bi 2 O 3 -based varistor ceramics. These investigations show that the rare earth oxides might play an important role in controlling the different operation parameters of these kinds of varistor ceramics.…”

Correlation between electrical properties and crystalline phases for ZnO-Bi2O3 based varistor ceramics with rare earth additives

“…It was reported that a new phase containing the rare earth element (referred to as the R-phase) segregates at ZnO grain boundaries. This phase consists of R-Bi-SbZn-(Mn)-O [6] and is strongly involved in the suppression of ZnO grain growth during the sintering process [7][8][9][10]. It was found that the addition of R 2 O 3 gave rise to a significant increase in the varistor voltage and leakage current, in addition to a larger energy absorption capacity.…”

“…This can be achieved by the addition of Sb or Si. It has also been shown that the addition of R 2 O 3 (R: rare earth element) leads to a reduction in the ZnO grain size and an increase in the varistor voltage [6][7][8][9][10][11][12][13][14][15][16]. It was reported that a new phase containing the rare earth element (referred to as the R-phase) segregates at ZnO grain boundaries.…”