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 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.

Synthesis of Pr6O11 Doped ZnO-Based Varistors by Pyrogenic Decomposition of Nitrate

2011 ◽  
Vol 675-677 ◽  
pp. 179-182
Author(s):  
Jian Feng Zhu ◽  
Guo Quan Qi ◽  
Hai Bo Mao ◽  
Hai Bo Yang ◽  
Fen Wang
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Linear Coefficient ◽  
Average Grain Size ◽  
Non Linear ◽  
Different Temperatures ◽  
Zno Powders ◽  
Doped Zno

Pr6O11 doped ZnO-based varistor powders were prepared by a method of pyrogenic decomposition nitrate, which were together with ZnO powders, made into rounded mass and sintered at different temperatures. The effects of sintering temperatures on the composition, microstructure and electrical properties of Pr6O11 doped ZnO-based varistors were investigated. The results show that the optimum sintering temperature is at 1150 °C with 6 μm ZnO average grain size and the samples possess the advantageous electrical properties: varistor voltage of about 480 V/mm, non linear coefficient reaching 44 and leakage current of 0.7 μA.

Effect of Sintering Temperature on Electrical Properties of ZnO Varistor Ceramics

2012 ◽  
Vol 442 ◽  
pp. 31-34
Author(s):  
Chang Qi Xia ◽  
Qi Bin Liu ◽  
Mo He
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Leakage Current ◽  
High Voltage ◽  
Sintering Temperature ◽  
Voltage Gradient ◽  
Varistor Ceramic ◽  
Zno Varistor ◽  
Zno Varistors ◽  
Ceramic Sintering

To obtain ZnO varistors with high voltage gradient, ZnO varistors were fabricated by traditional ceramic sintering technique, the effect of different sintering temperature (1135～1155 °C) on electrical properties of ZnO varistors were investigated. The experimental results show that with increasement of sintering temperature, the grain size of ZnO varistor ceramic becomes bigger, the voltage gradient of varistor decreases and the density is improved. When the sintering temperature is at 1135 °C, the voltage gradient of varistor is up to 329V/mm, the leakage current is 8μA and the density is 96.4%. When the sintering temperature is at 1140 °C, the voltage gradient of varistor is 301V/mm, the leakage current is 4μA and the density is 96.6%. Compared the results at 1135 °C with 1140 °C , it is found that the comprehensive electrical properties of ZnO varistors reach maximum at 1140 °C.

scholarly journals Structural and Electrical Studies on ZnO-Based Thin Films by Laser Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Shanyue Zhao ◽  
Yinqun Hua ◽  
Ruifang Chen ◽  
Jian Zhang ◽  
Ping Ji
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Electrical Properties ◽  
Grain Boundaries ◽  
Laser Irradiation ◽  
Nonlinear Coefficient ◽  
Acceptor State ◽  
Xrd Pattern ◽  
Electrical Studies ◽  
Structural And Electrical Properties

The effects of laser irradiation on the structural and electrical properties of ZnO-based thin films were investigated. The XRD pattern shows that the thin films were highly textured along thec-axis and perpendicular to the surface of the substrate. Raman spectra reveal that Bi2O3segregates mainly at ZnO-ZnO grain boundaries. After laser irradiation processing, the grain size of the film was reduced significantly, and the intrinsic atomic defects of grain boundaries and Bi element segregated at the grain boundary were interacted frequently and formed the composite defects of acceptor state. The nonlinear coefficient increased to 24.31 and the breakdown voltage reduced to 5.34 V.

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%.

Microwave Sintering Technology for the Production of Metal Oxide Varistors

1990 ◽  
Vol 189 ◽  
Author(s):  
G. McMahon ◽  
A. Pant ◽  
R. Sood ◽  
A. Ahmas ◽  
R.T. Holt
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Metal Oxide ◽  
Leakage Current ◽  
Microwave Sintering ◽  
Identical Composition

ABSTRACTA microwave sintering technology has been developed for the production of metal oxide varistors. The electrical properties (leakage current and non-linearity coefficient) of the microwave sintered devices were found to be comparable to those obtained for conventionally sintered varistors of identical composition. Additionally, the reference voltages were greater (by a factor of two) and the biaxial moduli of rupture were higher for the microwave sintered specimens. These differences have been attributed to the smaller grain size associated with the microwave sintered specimens.

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.

Synthesis of Nanocrystalline 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 Powder by a Citrate Method

2008 ◽  
Vol 368-372 ◽  
pp. 103-105
Author(s):  
Zhi Bin Tian ◽  
Xiao Hui Wang ◽  
Ji Li ◽  
Wei Zhao ◽  
Long Tu Li
Keyword(s):  
Grain Size ◽  
Electrical Properties ◽  
Traditional Method ◽  
Sintering Temperature ◽  
Ph Value ◽  
Precursor Solution ◽  
Milling Process ◽  
Citrate Method ◽  
Nano Powder ◽  
Average Grain Size

A citrate method to synthesize 0.94Bi0.5Na0.5TiO3-0.06BaTiO3 nano-powder was studied. The stable gel was obtained by the control of the pH value and temperature of the precursor solution. The BNBT nano-powder was produced after calcining the xerogel at 600°C~800°C. The average grain size of the powder calcined at 700°C for 3 h is 50 nm, and the grain size of the ceramic sintered at 1080°C is 0.7 μm. The sintering temperature used is 100°C lower than the BNBT ceramic prepared by traditional method, but the electrical properties were comparable. In addition, it was found that the ball-milling process has important effect on the morphology of the ceramics and the orientation crystals were eliminated due to the disintegration of agglomerates during milling.

Effect of Technological Parameters on the Microstructure and Electrical Properties of ZnO Varistors

2013 ◽  
Vol 820 ◽  
pp. 208-211
Author(s):  
Li Li ◽  
Qi Bin Liu
Keyword(s):  
Solid State ◽  
Electrical Properties ◽  
Leakage Current ◽  
Sintering Temperature ◽  
Voltage Gradient ◽  
Technological Parameters ◽  
Reaction Route ◽  
Conventional Solid State Reaction ◽  
Zno Varistors ◽  
Solid State Reaction Route

To improve voltage-gradient and to reduce the sintering temperature of ZnO varistors, high voltage-gradient ZnO varistors were synthesized with a conventional solid state reaction route. By means of SEM and DC parameter instrument for varistor, the influence of different technological parameters on microstructure, voltage-gradient and leakage current of ZnO varistors was investigated. The experimental results show that by using the process that presintering the additives at 850°C, the density is improved, the voltage-gradient is increased, and the leakage current is decreased. The optimum voltage-gradient and leakage current are 371V/mm and 3μA, respectively.

Influence of CeO2-Doping on the Electrical Properties of ZnO-Bi2O3-Based Varistor Ceramics

2016 ◽  
Vol 697 ◽  
pp. 262-266
Author(s):  
Zhan Chuan Cao ◽  
Liao Ying Zheng ◽  
Li Hong Cheng ◽  
Tian Tian ◽  
Guo Rong Li
Keyword(s):  
Grain Size ◽  
Phase Composition ◽  
Detection Limit ◽  
Electrical Properties ◽  
Barrier Height ◽  
Nonlinear Coefficient ◽  
Donor Concentration ◽  
Average Grain Size ◽  
Doped Zno ◽  
Density Of Interface States

The microstructure and electrical properties of CeO2-doped ZnO-Bi2O3-based varistors were investigated for different amounts of the dopant. The phase composition of CeO2-doped samples was similar to the undoped samples. Ce mainly segregated at the grain boundaries within the EDS detection limit. The average grain size decreased from 7.3 to 6.7 μm and the breakdown voltage increased from 438 to 501 V/mm when the content of CeO2 ranged from 0 to 0.2 mol%. The nonlinear coefficient increased from 38 to 51 when the content of CeO2 increased from 0 to 0.1 mol%., but the further doping caused it to decrease up to 44 at 0.2mol%. The leakage current decreased from 1 to 0.4 μA/cm2 when the content of CeO2 ranged from 0 to 0.1 mol%. Then it increased to 0.7 μA/cm2 at 0.2 mol%. The density of interface states, the barrier height and the donor concentration increased when the content of CeO2 ranged from 0 to 0.1 mol%, but decreased at 0.2 mol%. Hence, when the content ranges from 0 to 0.1 mol%, CeO2 acts as a donor and can improve the electrical properties.

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