Ultrahigh voltage-gradient ZnO-based varistor ceramics via hybrid cold sintering process/spark plasma sintering and post-annealing process

作者：Shenglin Kang, Xuetong Zhao, Qi Wang, Jie Liang, Jing Guo, Xilin Wang, Guilai Yin, Lijun Yang, Ruijin Liao · 发表于：Journal of Advanced Ceramics · 年份：2025 · DOI：10.26599/jac.2025.9221065 · 被引用次数：13 · 研究领域：ZnO doping and properties、Pigment Synthesis and Properties、Advanced ceramic materials synthesis

A high voltage gradient ( V g ) of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices. However, improving V g 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 V g of ~1832.71 V/mm, high nonlinear coefficient ( α ) of ~106.69, and low leakage current density ( J L ) of less than 0.2 μA/cm 2 . This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh V g .