Microstructural evaluation of rare-earth-zinc oxide-based varistor ceramics

Metal Oxide ZnO-Based Varistor Ceramics

Model for zinc oxide varistor

Zinc oxide varistors are very complex systems, and the dominant mechanism of voltage barrier formation in these systems has not been well established. Yet the MNDO quantum mechanical theoretical calculation was used in this work to determine the most probable defect type at the surface of a ZnO cluster. The proposed model represents well the semiconducting nature as well as the defects at the Z...

Synthesis Mechanism of Low-Voltage Praseodymium Oxide Doped Zinc Oxide Varistor Ceramics Prepared Through Modified Citrate Gel Coating

High demands on low-voltage electronics have increased the need for zinc oxide (ZnO) varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synth...

Ternary Rare Earth Transition Metal Zinc Compounds

Forty eight new com pounds RT2Z n2o were prepared by annealing cold-pressed pellets o f the elem ental com ponents in an argon atm osphere. They crystallize with the cubic CeCr^Abo type structure (Fd3m , Z = 8), which was refined from single-crystal diffractom eter data o f TbFeiZn^o (a = 1411.1(1) pm), Y Ru2Z n2o (a = 1422.6(1) pm), D yRu2Z n2o (a = 1422.1(1) pm), G dC o2Z n2o (a = 1406.0(1) p...

Microstructural Design of Toughened Ceramics

The fracture toughness of ceramics can be improved by the incorporation of a variety of discontinuous, elastic reinforcing phases that generate a crack-bridging zone. Recent models of toughening by crack-bridging processes are discussed and used to describe the behavior observed in whisker-reinforced ceramics. The toughening response in ceramics reinforced with other types of discontinuous rein...