Influence of Pr6O11 on the Characteristics and Microstructure of Zinc Varistors

2008 ◽  
Vol 368-372 ◽  
pp. 500-502 ◽  
Author(s):  
Jian Feng Zhu ◽  
Ji Qiang Gao ◽  
Fen Wang ◽  
Ping Chen
Keyword(s):  
Electrical Properties ◽  
Grain Growth ◽  
Leakage Current ◽  
Threshold Voltage ◽  
Spinel Phase ◽  
Nonlinear Coefficient ◽  
Pyrochlore Phase ◽  
Voltage Ratio ◽  
Zno Crystal ◽  
Microstructural Homogeneity

The influence of the amount of Pr6O11 additions on the microstructure and electrical properties of varistors ceramics in the ZnO-Bi2O3 system was investigated. Samples with a low level of Pr6O11 (0.1wt %) have high microstructural homogeneity, which enhances the nonlinear coefficient greatly, and decreases the leakage current without change of voltage ratio. When the Pr6O11 content reached 7wt%, the ZnO grain growth was restricted and the threshold voltage was improved from 275v/mm to 440v/mm. The additive of Pr6O11 changed the process of creating spinel phase, which came from the decomposition of pyrochlore phase. This type of small size phase has more dragging force on the ZnO crystal, which make the whole materials more uniform and compact.

Microstructure and Electrical Properties of ZnO–Bi2O3-Based Varistor Ceramics by Different High-Energy Ball Milling Time

2012 ◽  
Vol 490-495 ◽  
pp. 3391-3395
Author(s):  
Cheng Hua Zhang ◽  
Ming Shuang Li ◽  
Dong Xu ◽  
Yong Fang Chen ◽  
Yuan Ling Liu ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ball Milling ◽  
Leakage Current ◽  
Threshold Voltage ◽  
Nonlinear Coefficient ◽  
High Energy ◽  
Sem Analysis ◽  
High Energy Ball Milling ◽  
Electrical Measurements ◽  
Energy Ball

The microstructure and electrical properties of ZnO-Bi2O3-based varistor ceramics prepared by the high-energy ball milling were studied. The varistor ceramics samples were characterized by XRD and SEM analysis, as well as by dc electrical measurements, such as the nonlinearity coefficients, leakage current and threshold voltage. The best electrical characteristics were found in sample by the high-energy ball milling 1 h and sintered at 1000 °C for 2 h, which exhibited the threshold voltage was 457 V/mm, the nonlinear coefficient was 59.3 and the leakage current was 1.18 μA.

Microstructure and Electrical Properties of La2O3-Doped ZnO-Bi2O3 Based Varistor Ceramics

2009 ◽  
Vol 79-82 ◽  
pp. 2007-2010 ◽  
Author(s):  
Dong Xu ◽  
Xiao Nong Cheng ◽  
Ming Song Wang ◽  
Li Yi Shi
Keyword(s):  
Electrical Properties ◽  
Leakage Current ◽  
Threshold Voltage ◽  
Nonlinear Coefficient ◽  
Voltage Gradient ◽  
Solid Reaction ◽  
Reaction Route ◽  
Doped Zno

La2O3-doped ZnO-Bi2O3-based varistor ceramics were obtained by a solid reaction route, and the microstructure and electrical properties of the varistor ceramics were studied in this paper. The results showed with addition of 0-1.00mol% La2O3, La2O3-doped ZnO-based varistor ceramics were prepared in this paper with the voltage gradient of 77-503V/mm, the nonlinear coefficient of 2.4-36.8, and the leakage current of 0.09-494μA. The results also showed with addition of 0.08mol% La2O3, La2O3-doped ZnO-based varistor ceramics exhibit comparatively ideal comprehensive electrical properties. Such as the threshold voltage was 320V/mm, the nonlinear coefficient was 36.8 and the leakage current was 0.29μA. The doping of La2O3 affects the form and decomposition of the pyrochlore.

Effect of WO3 Doping on Microstructural and Electrical Properties of ZnO-Pr6O11 Based Varistor Materials

2013 ◽  
Vol 591 ◽  
pp. 54-60
Author(s):  
Xiu Li Fu ◽  
Yan Xu Zang ◽  
Zhi Jian Peng
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Grain Growth ◽  
Doping Level ◽  
Nonlinear Coefficient ◽  
Current Voltage ◽  
Average Grain Size ◽  
Current Voltage Characteristics ◽  
Voltage Performance

The effect of WO3doping on microstructural and electrical properties of ZnO-Pr6O11based varistor materials was investigated. The doped WO3plays a role of inhibitor in ZnO grain growth, resulting in decreased average grain size from 2.68 to 1.68 μm with increasing doping level of WO3from 0 to 0.5 mol%. When the doping level of WO3was lower than 0.05 mol%, the nonlinear current-voltage characteristics of the obtained varistors could be improved significantly with increasing amount of WO3doped. But when the doping level of WO3became higher, their nonlinear current-voltage performance would be dramatically deteriorated when more WO3was doped. The optimum nonlinear coefficient, varistor voltage, and leakage current of the samples were about 13.71, 710 V/mm and 13 μA/cm2, respectively, when the doping level of WO3was in the range from 0.03 to 0.05 mol%.

Electrical Properties of a TiO2-SrO Varistor System

2014 ◽  
Vol 975 ◽  
pp. 168-172
Author(s):  
Tiago Delbrücke ◽  
Igor Schmidt ◽  
Sergio Cava ◽  
Vânia Caldas Sousa
Keyword(s):  
Titanium Dioxide ◽  
Electrical Properties ◽  
Field Strength ◽  
Leakage Current ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Breakdown Field ◽  
Strontium Oxide ◽  
Breakdown Field Strength

The addition of different dopants affects the densification and electrical properties of TiO2 based varistor ceramics. The nonlinear current (I) and voltage (V) characteristics of titanium dioxide are examined when doped with small quantities (0.5-2 at.%) of strontium oxide. This paper discusses the electrical properties of such an SrO doped TiO2 system, and demonstrates that some combinations produce electrical properties suitable for use as low voltage varistors. The high value of the nonlinear coefficient (α) (6.6), the breakdown field strength (Eb) (328 V/cm) and the leakage current (Ir) (0.22 mA/cm2) obtained in a system newly doped with SrO, are all adequate properties for application in low voltage varistors.

Microstructure Design and Optimization of ZnO-Bi2O3-Sb2O3 Based Ceramic Varistors

2012 ◽  
Vol 519 ◽  
pp. 232-235
Author(s):  
Cheng Peng ◽  
Dan Xie ◽  
Tian Ling Ren ◽  
Zhi Jian Peng
Keyword(s):  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Nonlinear Coefficient ◽  
Electrical Performance ◽  
Microstructure Design ◽  
Dwelling Time ◽  
Design And Optimization ◽  
Different Temperatures ◽  
The Given

ZnO-based varistor; Microstructure; design and optimization; Electrical properties Abstract. ZnO-based ceramic varistors of a commercially available ZnO-based varistor composition were prepared under sintering system of different temperatures and dwelling times. The microstructure and electrical properties were investigated systematically and optimized. With increasing sintering temperature from 1035 to 1175 °C and dwelling time from 1 to 4 h, the composition and microstructure phases of the samples almost had no change, but the samples prepared at 1035 and 1175 °C presented the highest porosity; the nonlinear coefficient generally increased, but the samples prepared at 1145 and 1175 °C almost presented the same value of nonlinear coefficient; the varistor voltage decreased; and the samples sintered at 1035 and 1175 °C presented the highest leakage current. From the microstructure and electrical performance, it was proposed that, for the given varistors, the optimum sintering system was 1145 °C for 2 h.

Effect of Sintering Temperature on the Microstructure and Electrical Properties of SnO2-Based Varistors

2012 ◽  
Vol 724 ◽  
pp. 323-326
Author(s):  
Guang Liang Hu ◽  
Jian Feng Zhu
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Nonlinear Coefficient

SnO2-based varistors were successfully fabricated from the mixed powders, SnO2, Co2O3, Nb2O5 and Cr2O3. The effects of sintering temperature (1250, 1300, 1350 and 1400 °C) on the microstructure and electrical properties were investigated. The results reveal that the grain size increases with increasing the sintering temperature, and the breakdown electrical filed decreases gradually. When the sintering temperature was 1300 °C, the nonlinear coefficient of the as fabricated SnO2 based varistors presents the maximum of 27. Meanwhile, the leakage current possesses the minimum of 4.5 µA.

Microstructure and Electrical Properties of Y2O3 and Sb2O3 Co-Doped ZnO-Based Varistors

2014 ◽  
Vol 602-603 ◽  
pp. 830-835
Author(s):  
Xiu Li Fu ◽  
Yan Xu Zang ◽  
Zhi Jian Peng
Keyword(s):  
Electrical Properties ◽  
Leakage Current ◽  
Breakdown Voltage ◽  
Nonlinear Coefficient ◽  
Current Increase ◽  
Atom Ratio ◽  
Mean Size ◽  
Doped Zno ◽  
Co Doped ◽  
Better Than

Through a conventional ceramic process, Y2O3 and Sb2O3 co-doped ZnO-based varistors were prepared. The microstructure and electrical properties of the as-prepared varistors were investigated. Y2O3 could act as an inhibitor to the growth of ZnO grains when working with Sb2O3. The mean size of ZnO grains in the Sb2O3 and Y2O3 co-doped samples was smaller than those of the samples only added with Y2O3 or Sb2O3. And with appropriately increased ratio of Y:Sb, it would result in increased sample densification. When the doping level of Y2O3 was small, the nonlinear coefficientand breakdown voltage of the varistors would increase with increasing doping amounts of Y2O3, and the leakage current would decrease. However, when Y2O3 was doped without Sb2O3, both the nonlinear coefficientand breakdown voltage of the varistors would decrease sharply, thus the leakage current increase dramatically. The electrical properties of the Sb2O3 and Y2O3 co-doped varistors would be better than those of the samples only added with Y2O3 or Sb2O3, and when the Y:Sb atom ratio was 5, the nonlinear coefficients, breakdown voltages and leakage current of the varistors reached their optimum values of 777 V/mm, 23 and 0.17 mA/cm2, respectively.

Effect of Ho2O3 Doping on Performance of ZnO Varistor

2008 ◽  
Vol 368-372 ◽  
pp. 507-509
Author(s):  
Zhen Ya Lu ◽  
Yu Xiang Liu ◽  
Zhi Wu Chen ◽  
Jian Qing Wu
Keyword(s):  
Electrical Properties ◽  
Grain Growth ◽  
Nonlinear Coefficient ◽  
High Current ◽  
Zno Varistor ◽  
Current Area ◽  
Electric Filed ◽  
Nonlinear Performance ◽  
Effective Dopant ◽  
Surge Current

The effect of Ho2O3 doping on the electrical properties and microstructure of ZnO base varistor was investigated. It was found that Ho2O3 is an effective dopant for increasing the breakdown electric filed. The Ho2O3 doping can also improve the nonlinear performance both in low and high current area. But excessive doping of Ho2O3 will decrease the withstanding surge current. With 0.8mol% Ho2O3 doping, the varistor samples exhibit a breakdown voltage of about 400V/mm, a nonlinear coefficient of 80 and the withstanding surge current of 8/20μs, waveshape is higher than 5kA. Ho2O3 dopant can hinder ZnO grain growth and make the crystal grains more uniform.

Effect of TiO2 Doping on Microdefects and Electrical Properties of ZnO-Based Varistors

2017 ◽  
Vol 373 ◽  
pp. 197-200
Author(s):  
Zheng Ying Chen ◽  
Mei Yu Li ◽  
Yan Wan ◽  
Li Fang Han ◽  
Yu Yang Huang ◽  
...  
Keyword(s):  
Electrical Property ◽  
Electrical Properties ◽  
Leakage Current ◽  
Positron Lifetime ◽  
Nonlinear Coefficient ◽  
Low Leakage ◽  
Low Leakage Current ◽  
Lifetime Spectrum ◽  
The Mean ◽  
Varistor Property

Positron lifetime spectrum and electrical property measurements were performed on ZnO-based ceramics doped with different contents of TiO2. For ZnO-based ceramics with TiO2 content less than 1.8 mol%, the mean positron lifetime of the ZnO-based ceramic decreases with increasing in TiO2 content, and reaches a minimum value at 1.8 mol% TiO2. As the TiO2 content higher than 1.8 mol%, the mean positron lifetime increases with TiO2 content. The ZnO-based varistor with 1.8 mol% TiO2 exhibites an optimized varistor property; it has a relatively low leakage current IL, a relatively low breakdown voltage VB, and a relatively high nonlinear coefficient α. The effects of TiO2 doping on microdefects and electrical properties of ZnO-based varistors were discussed.

scholarly journals Microstructural and Nonlinear Properties of Zn-V-Mn-Nb-O Varistor Ceramics with Gd2O3 Substitution for Low Voltage Application

2017 ◽  
Vol 268 ◽  
pp. 181-185 ◽  
Author(s):  
Nor Hasanah Isa ◽  
Zakaria Azmi ◽  
Raba’ah Syahidah Azis ◽  
Zahid Rizwan
Keyword(s):  
Electrical Properties ◽  
Grain Growth ◽  
Leakage Current Density ◽  
Current Density ◽  
Triple Point ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Electrical Field ◽  
Nonlinear Properties ◽  
Voltage Application

The effect of Gd2O3 substitution on the microstructural and electrical properties of Zn-V-Mn-Nb-O varistor ceramics sintered at 900°C was investigated. XRD, SEM, and EDAX results show that the GdMnO3 and GdVO4 phases formed at the grain boundaries and triple point junctions. Gd2O3 substitution inhibited the grain growth from 3.85 to 3.06 μm and increased the sintered ceramics density from 5.12 to 5.19 g/cm3.The samples containing the amount of 0.03 mol% Gd2O3 exhibit an optimum nonlinear coefficient α value which is 9.91, highest breakdown electrical field which is 88.48 V/mm and lowest leakage current density which is 0.11 mA/cm2 in low voltage application.

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