Influence of sintering on microstructure and electrical properties of ZnO-based multilayer varistor (MLV)

Lee, Wen-Shi; Chen, W. T.; Lee, Y. C.; Yang, Tony L.; Su, Che Yi; Hu, Chi‐Ming

doi:10.1016/j.ceramint.2006.02.017

Cited by 17 publications

(11 citation statements)

References 10 publications

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“…The breakdown voltages were found to be 130, 80, and 66 V for varistors sintered at 1000, 1050, and 1100 ℃, respectively. The observed decrease in breakdown voltage with the rising sintering temperature is consistent with the results of several authors [11,16,18,23,25]. Lower values of the breakdown voltage for the varistors sintered at higher temperatures are due to the grain growth and consequently a decrease in the grain boundary number between the adjacent electrodes.…”

Section: Resultssupporting

confidence: 91%

“…Uniform dopant distribution inside the entire varistor is known to improve significantly leakage current and nonlinear properties of a varistor [22]. Furthermore, broad grain size distribution has been reported to cause poor performance in ESD conditions and shorter life time of multilayer varistors [23]. Pr doped ZnO multilayer chip varistors were found to exhibit better ESD withstand capability than those based on Bi doped ZnO [24].…”

Section: ••mentioning

confidence: 99%

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Influence of processing on microstructure and electrical characteristics of multilayer varistors

2019

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The paper reports on the influence of processing on microstructure and electrical properties of multilayer varistors based on zinc oxide doped with Bi 2 O 3 , Sb 2 O 3 , Co 2 O 3 , MnO, Cr 2 O 3 , B 2 O 3 , and SiO 2. 0.5-1 wt% of AlF 3-CaB 4 O 7 was used as a new effective sintering aid. The behavior of green laminates during heating was characterized using differential thermal analysis and a heating microscope. As revealed by XRD, SEM, and EDS methods, the varistor layers are composed of ZnO grains of 1-5 μm size, submicrometer spinel and pyrochlore grains situated at the ZnO grain boundaries, and nanometric Bi 2 O 3-rich films surrounding ZnO grains. Complex impedance studies carried out in the frequency range of 0.01 Hz-2 MHz at temperatures changing from-30 to 150 ℃ imply the formation of semiconducting grains and insulating grain boundaries. Frequency dependence of dielectric permittivity shows a high plateau at lower frequencies, typical for barrier layer capacitance effect. The fabricated multilayer varistors show nonlinear current-voltage characteristics with a high nonlinear coefficient of 26-38. The breakdown voltage was found to decrease within the range of 66-130 V with sintering temperature increasing from 1000 to 1100 ℃. Good surge current capability of the varistors was confirmed by the tests using 8/20 μs pulses.

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Section: Resultssupporting

confidence: 91%

Section: ••mentioning

confidence: 99%

Influence of processing on microstructure and electrical characteristics of multilayer varistors

2019

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“…Demand for a permanent progress in miniaturization and integration scale as well as broadening of the application range of low voltage electronic devices has created an enhanced need for multilayer varistors for the protection of such devices against high voltage transients and surges (Lee et al, 2006(Lee et al, , 2007Rubia et al, 2007;Kuo and Tuan, 2008;Peiteado et al, 2009;Kuo and Tuan, 2010;Pan et al, 2010;Hirose et al, 2012;Hofstätter et al, 2013). Multilayer varistors are fabricated in tape casting/lamination/cofiring process, similar to that widely used for multilayer capacitors.…”

Section: Introductionmentioning

confidence: 99%

Tape casting and properties of Pr₂O₃-doped ZnO multilayer varistors

Kulawik

Szwagierczak

Synkiewicz

2014

Microelectronics International

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Purpose -This paper aims to fabricate and characterize ZnO-based multilayer varistors. Design/methodology/approach -Tape casting technique was utilized for preparation of multilayer varistors based on ZnO doped with Pr, Bi, Sb, Co, Cr, Mn and Si oxides. Scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) methods were used to study the microstructure, elemental and phase compositions, respectively, of the varistors. Dielectric properties were investigated by impedance spectroscopy. Current-voltage (I-U) dependences were measured to characterize nonlinear behavior of the fabricated varistors. Findings -XRD, SEM and EDS studies revealed dense microstructure of ceramic layers with ZnO grains sized 1-4 m surrounded by nanometric Bi-rich films, submicrometer Zn 7 Sb 2 O 12 spinel grains and needle-shaped Pr 3 SbO 7 crystallites. Praseodymium oxide was found to be very effective as an additive restricting the ZnO grain growth. I-U characteristics of the fabricated multilayer varistors were nonlinear, with the nonlinearity coefficients of 23-27 and 19-51 for the lower and higher Pr 2 O 3 content, respectively. The breakdown voltages were 60-150 V, decreasing with increasing sintering temperature. Originality/value -Low-temperature cofired ceramics technology enables attaining a significant progress in miniaturization of electronic passive components. Literature concerning application of this technology for multilayer varistors fabrication is limited. In the present work, the results of XRD, SEM and EDS studies along with the I-U and complex impedance dependences are analyzed to elucidate the origin of the observed varistor effect. The influence of sintering temperature and Pr 2 O 3 -doping level was investigated.

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“…Since the sintering temperatures of commercial ZnO varistor materials are higher than the melting point of silver (961°C), an expensive silver/ palladium alloy is commonly used as the internal electrodes for multilayer chip varistors. The multilayer chip varistors are fabricated by a conventional multilayer ceramic capacitor technology and used for protecting lowvoltage integrated circuits from electrostatic discharge [19,20]. Therefore, in order to reduce the manufacturing cost and use pure silver as an internal electrode in multilayer devices, it is important to research the ZnO varistor materials sintered at low sintering temperatures.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature sintering and electrical properties of Co-doped ZnO varistors

Chu

et al. 2014

J Mater Sci: Mater Electron

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ZnO-Bi 2 O 3 -B 2 O 3 -based varistors doped with each kind of cobalt oxides were prepared by conventional ceramic processing. The effects of CoO, Co 2 O 3 and Co 3 O 4 on the microstructure and the electrical characteristics of varistor samples sintered at 880°C were investigated separately. Analysis of microstructure indicated the cobalt cations were distributed both in grain regions and grain boundary regions and no crystalline phases containing cobalt were detected in XRD patterns for the samples with various cobalt oxides. All these cobalt oxides could effectively enhance the varistor performance by effectively increasing the nonlinear coefficient and lowing the leakage current, while the breakdown voltage fields increased slightly. Capacitance-voltage characteristics showed the potential barriers of varistor samples increased with the addition of each cobalt oxide. It was found that the addition of same amount of cobalt cations in various cobalt oxides had a different effect on the varistor samples. Best electrical properties were obtained for the varistor sample containing Co 3 O 4 , in which the nonlinearity coefficient is 28.5, the leakage current density is 3.4 lA and the breakdown voltage field is as low as 260 V/mm.

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Influence of sintering on microstructure and electrical properties of ZnO-based multilayer varistor (MLV)

Cited by 17 publications

References 10 publications

Influence of processing on microstructure and electrical characteristics of multilayer varistors

Influence of processing on microstructure and electrical characteristics of multilayer varistors

Tape casting and properties of Pr₂O₃-doped ZnO multilayer varistors

Low-temperature sintering and electrical properties of Co-doped ZnO varistors

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Influence of sintering on microstructure and electrical properties of ZnO-based multilayer varistor (MLV)

Cited by 17 publications

References 10 publications

Influence of processing on microstructure and electrical characteristics of multilayer varistors

Influence of processing on microstructure and electrical characteristics of multilayer varistors

Tape casting and properties of Pr2O3-doped ZnO multilayer varistors

Low-temperature sintering and electrical properties of Co-doped ZnO varistors

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Tape casting and properties of Pr₂O₃-doped ZnO multilayer varistors