Effects of SiO2 and Cr2O3 on the formation process of ZnO varistors

Kanai, H.; Imai, Motomasa

doi:10.1007/bf00551935

Cited by 22 publications

(4 citation statements)

References 4 publications

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“…ZnO varistors have been successfully applied to the surge protector in electrical transmission and transient overvoltage or circuits to prevent lightning strikes due to their excellent nonlinearly electrical characteristics which originate from the grain boundaries [1]. It is generally believed that ZnO varistors are made by mixing zinc oxide powders with various oxide additives, such as Bi 2 O 3 [2,3], Sb 2 O 3 [4,5], Co 2 O 3 [6,7], Sc 2 O 3 [8], MnO 2 [9], Cr 2 O 3 [10,11], and TiO 2 [12]. At present, most ZnO-based varistors are prepared by a conventional sintering method.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Peng

Deng

Niu

et al. 2020

Preprint

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Abstract The dense ZnO-Bi2O3-MnO2-xSiO2 (ZBMS) varistors for x= 0, 1, 2, 3 wt.% were fabricated by flash sintering method under the low temperature of 850 ℃ within 2 minutes. The sample temperature was estimated by a black body radiation model in the flash sintering process. The crystalline phase assemblage, density, microstructure, and electrical characteristics of the flash-sintered ZBMS varistors with different SiO2 doped content were investigated. According to the XRD analysis, many secondary phases were detected due to the SiO2 doping. Meanwhile, the average grain size decrease with increasing SiO2-doped content. The improved nonlinear characteristics were obtained in SiO2-doped samples, which can be attributed to the ion migration and oxygen absorption induced by the doped SiO2. The flash-sintered ZBMS varistor ceramics for x=2 wt.% exhibited excellent comprehensive electrical properties, with the nonlinear coefficient of 24.5, the threshold voltage and leakage current of 385 V×mm-1 and 11.8 µA, respectively.

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Section: Introductionmentioning

confidence: 99%

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Peng

Deng

Niu

et al. 2020

Preprint

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“…Bi 2 O 3 serves as an inducer of the double Schottky barrier (DSB), which generates the nonlinear electrical properties but with a low α value . In order to obtain excellent properties, Sb 2 O 3 and transition‐metal oxides such as Co 2 O 3 , Cr 2 O 3 , TiO 2 , MnO 2 , etc., are introduced. Investigations have shown that Cr 2 O 3 , Co 2 O 3 , and MnO 2 are involved in the formation of interface states and deep bulk traps at grain boundaries, which increase the barrier height to get higher nonlinear coefficient and lower leakage current.…”

Section: Introductionmentioning

confidence: 99%

The effect of SiO₂on electrical properties of low‐temperature‐sintered ZnO–Bi₂O₃–TiO₂–Co₂O₃–MnO₂‐based ceramics

Bai

Zhang

et al. 2016

J Am Ceram Soc

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ZnO–Bi2O3–TiO2–Co2O3–MnO2‐based (ZBTCM) varistors were fabricated via the conventional solid‐state method, and the effect of SiO2 content on the phase transformation, microstructure, and electrical properties of the ZBTCM had been investigated. Results showed that this varistor can be sintered at a low temperature of 880°C with a high sintering density above 0.95 of the ZnO theoretical density. In these components, SiO2 acts as a controller in ZnO grain growth, decreasing the grain size of ZnO from 3.67 to 1.92 μm, which in turn results in an increase in breakdown voltage E1mA from 358.11 to 1080 V/mm. On the other hand, SiO2 has a significant influence on the defect structure and component distribution at grain‐boundary regions. When SiO2 content increases from 0 to 4 wt%, the value of the interface state density (Ns) increases sharply. At the same time, the electrical properties are improved gradually, and reach an optimized value with the nonlinear coefficient (α) up to 54.18, the barrier height (ϕb) up to 2.90 eV, and the leakage current (IL) down to 0.193 μA/cm2.

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“…ZnO varistors have been successfully applied to the surge protector in electrical transmission and transient overvoltage or circuits to prevent lightning strikes due to its excellent nonlinearly electrical characteristics which originated from the grain boundaries. [1] It is generally believed that ZnO varistors are made by mixing zinc oxide powders with various oxide additives, such as Bi2O3 [2,3], Sb2O3 [4,5], Co2O3 [6,7], Sc2O3 [8], MnO2 [9], Cr2O3 [10,11], and TiO2 [12]. In addition, ZnO as the addition can not only shift the tri-critical point to room temperature for the Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics, but also solve evaporation and hygroscopicity problem of K2O in the KNbO3 ceramics.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Peng

Niu

Shi

et al. 2020

Preprint

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The dense ZnO-Bi 2 O 3 -MnO 2 - x SiO 2 (ZBMS) varistors were fabricated by flash sintering method under the low temperature of 850 o C within 2 minutes. The phase structure, density, microstructure, and electrical characteristics of the flash-sintered ZBMS varistors with different SiO 2 doping content were investigated. According to the XRD analysis, many secondary phases were detected due to the doping of SiO 2 . Meanwhile, the average grain size decrease with increasing SiO 2 doping content. In addition, the electrical properties of all samples were analyzed. The improved nonlinear characteristics were obtained in SiO 2 doped samples, which can be attributed to the ion migration and oxygen absorption induced by the doping of SiO 2 . The flash-sintered ZBMS varistor ceramics exhibited excellent comprehensive electrical properties, with the nonlinear coefficient of 24.5, the threshold voltage and leakage current of 385 V/mm and 11.8 µA, respectively.

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Effects of SiO2 and Cr2O3 on the formation process of ZnO varistors

Cited by 22 publications

References 4 publications

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

The effect of SiO₂on electrical properties of low‐temperature‐sintered ZnO–Bi₂O₃–TiO₂–Co₂O₃–MnO₂‐based ceramics

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

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Effects of SiO2 and Cr2O3 on the formation process of ZnO varistors

Cited by 22 publications

References 4 publications

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

The effect of SiO2on electrical properties of low‐temperature‐sintered ZnO–Bi2O3–TiO2–Co2O3–MnO2‐based ceramics

Fabrication and electrical characteristics of flash-sintered SiO2-doped ZnO-Bi2O3-MnO2 varistors

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The effect of SiO₂on electrical properties of low‐temperature‐sintered ZnO–Bi₂O₃–TiO₂–Co₂O₃–MnO₂‐based ceramics