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

Advances in understanding of damage formation during laser-assisted milling of ZnO-based varistor ceramics

“…ZnO ceramics is based on the ZnO-Bi 2 O 3 system with small amounts of Bi 2 O 3 and other additives such as Sb 2 O 3 , Co 2 O 3 , MnO 2 and Cr 2 O 3 . Its complicated microstructure consists of ZnO grains, a secondary spinel phase, and a Bi-rich intergranular phase, and intergranular fracture is the predominant fracture mode [25]. Studies of LAM on other ceramics showed a change in material removal mechanisms when the workpiece material is heated above the glass transition temperature (T g ) of the intergranular glassy phase [26].…”

Microstructure and properties of ZnO-Bi2O3-based varistor ceramics via flash sintering

“…In general, the conventional sintering (CS) for the fabrication of ZnO–Bi 2 O 3 -based ceramics often requires high sintering temperature and hours of processing time, which suffers from some disadvantages, such as time, cost and energy waste (Zhang et al , 2019). On the one hand, the high sintering temperature is not beneficial to the Bi 2 O 3 liquid-phase sintering in the ZnO–Bi 2 O 3 -based varistor ceramics – because of the volatilization of Bi 2 O 3 under the temperature >825°C, which limits the electrical performance (Xu et al , 2009; Xu et al , 2013). On the other hand, the long sintering time is beneficial to grain growth, which can become an obstacle for high voltage ZnO-based ceramic preparing (Li et al , 2015; Raj et al , 2011).…”

Simultaneously Enhanced Potential Gradient and Nonlinearity of ZnO Varistor Ceramics by MnO Doping with Nano-Sized ZnO Powders

“…High-performance ZnO varistor ceramics with a high potential gradient, high nonlinear coefficient and low leakage current are urgently required due to the increasing requirements in the fields of device miniaturization, ultra-high-voltage power systems, high-speed electrified railways, and integrated circuits, etc. [3][4][5][6][7] The potential gradient (E 1mA ) of ZnO varistor ceramics is proportional to the number of grain boundaries (GB) per unit length and the breakdown voltage of a single GB, which is approximately constant at ~3 V [1]. Therefore, the commonly accepted approach to enhance the potential gradient is to reduce the grain size, which is generally achieved by optimizing doping [4,[8][9][10], sintering [11][12][13] and nano-sized raw materials [5,[14][15][16][17][18][19].…”