TY  - JOUR
AU  - Kang, Shenglin
AU  - Zhao, Xuetong
AU  - Wang, Qi
AU  - Liang, Jie
AU  - Guo, Jing
AU  - Wang, Xilin
AU  - Yin, Guilai
AU  - Yang, Lijun
AU  - Liao, Ruijin
PY  - 2025
TI  - Ultrahigh voltage-gradient ZnO-based varistor ceramics via hybrid cold sintering process/spark plasma sintering and post-annealing process
JO  - Journal of Advanced Ceramics
SN  - 2226-4108
SP  - 9221065
VL  - 14
IS  - 5
AB  - A high voltage gradient (Vg) of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices. However, improving Vg of ZnO-based varistor ceramics through conventional high-temperature sintering process remains a significant challenge. Here, we present a strategy to fabricate ultrahigh voltage-gradient ZnO-based varistor ceramics by combining cold sintering process/spark plasma sintering (CSP–SPS) with post-annealing process. Employing CSP–SPS, the ZnO-based varistor ceramics were initially densified at 300 °C and subsequently annealed at a low temperature of 700–900 °C. CSP–SPS technique combined with a low annealing temperature enables the production of ZnO-based varistor ceramics with fine and homogeneous microstructures, while suppressing the volatilization of Bi-rich phases at grain boundaries. This approach achieves the ultrahigh Vg of ~1832.71 V/mm, high nonlinear coefficient (α) of ~106.69, and low leakage current density (JL) of less than 0.2 μA/cm2. This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh Vg.
UR  - https://doi.org/10.26599/JAC.2025.9221065
DO  - 10.26599/JAC.2025.9221065