Microstructural and electrical characteristics of SiO2 doped ZnO-Bi2O3 varistors

Goel, Rahul; Sil, Anjan; Anand, Himanshu

doi:10.1007/bf02745675

Cited by 6 publications

(3 citation statements)

References 13 publications

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“…With higher amounts of SiO 2 , the Zn 2 SiO 4 phase forms, a spinel phase structure, which, like the Zn 2.33 Sb 0.67 O 4 antimony spinel, restrains the growth of ZnO grains. Besides, Zn 2 SiO 4 grains offer a high electrical resistance, inhibiting both the electron transport and the mass transport of ions, so fitting the requirements for the inclusions we are seeking. Accordingly, compositions with different amounts of SiO 2 were prepared to investigate the effect of Si‐doping on the varistor leakage current.…”

Section: Resultsmentioning

confidence: 99%

Microstructure Engineering to Drastically Reduce the Leakage Currents of High Voltage ZnO Varistor Ceramics

et al. 2012

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The energetic losses associated with the leakage currents can represent a serious problem for the efficient performance of ZnO-based varistor ceramics. However, by properly tailoring the microstructure of these ceramics, the leakage currents can be drastically reduced. Pursuing this goal, two intended doping strategies have been attempted over a standard high-voltage varistor formulation based on the ZnO-Bi 2 O 3 -Sb 2 O 3 ternary system. The first strategy focuses on the stabilization of the secondary Zn 2.33 Sb 0.67 O 4 spinel particles; on cooling the ceramic, this spinel phase reversely transforms into a pyrochlore conductive structure whose presence favors the current flow in the varistor prebreakdown region (i.e., high leakage current values). A certain amount of TiO 2 incorporated into the spinel lattice impedes its reverse transformation to pyrochlore, thus reducing the varistor leakage current. The second strategy leans on the insertion of an insulating phase in between the skeleton of Bismuth-rich phases. This skeleton provides a continuous network through the whole varistor microstructure for the current to flow, so the inclusion of an insulating phase may serve as a physical blockade to break off that connectivity. Such a phase is yielded by properly doping with SiO 2 . Eventually, the combination of both strategies leads to a decrease of two orders of magnitude in the varistor leakage current.

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Section: Resultsmentioning

confidence: 99%

Microstructure Engineering to Drastically Reduce the Leakage Currents of High Voltage ZnO Varistor Ceramics

et al. 2012

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“…2,8 For samples C-E, the effective Noticeably, SiO 2 coating may also contribute to the enhancement of a. Kutty and Ezhilvalavan 16 reported that SiO 2 addition could enhance the nonlinear coefficient of a ZnO varistor by modifying the interface trap states at the grain boundary. Goel et al 13 pointed out that SiO 2 addition enabled an increased nonlinear coefficient in the way that an intergranular SiO 2 rich phase inhibited electron transport due to its high electric resistance.…”

Section: (C) Microstructure and Electrical Properties Of Sintered Zno...mentioning

confidence: 99%

“…SiO 2 addition prompts the formation of Zn 2 SiO 4 , which could inhibit ZnO grain growth the during sintering process. [12][13][14] Meanwhile, some literature 13,[15][16][17] proposed that SiO 2 addition also promotes the improvement of the nonlinear coefficient of ZnO varistors. However, the simple way of adding SiO 2 in conventional solid mixing exhibits a finite effect on the modification of the varistor microstructure.…”

Section: Introductionmentioning

confidence: 99%