The Electrical Properties and Impedance Analysis of ZnO Varistors Doped with Different Cu2O Contents

2014 ◽  
Vol 681 ◽  
pp. 173-176
Author(s):  
Ji Wei Fan ◽  
Hui Jun Zhao ◽  
Xiao Li Zhang
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Leakage Current ◽  
Impedance Analysis ◽  
Boundary Resistance ◽  
Zno Varistors ◽  
Good Agreement

The Cu2O addition deteriorates the electrical properties of ZnO varistors, which is a good agreement with similar findings on Ag2O additions. The best fitted impedance analysis reveals that the Cu2O addition increases grain resistance and lowers the grain boundary resistance, results in low nonlinearity and higher leakage current of ZnO varistors.

The Effects of Cu Dopant on the Microstructure and Non-Ohmic Electrical Properties of ZnO Varistors

2011 ◽  
Vol 343-344 ◽  
pp. 160-165 ◽  
Author(s):  
Ji Wei Fan ◽  
Xiao Peng Li ◽  
Zhen Guo Zhang ◽  
Zhi Qiang Jiao ◽  
Xiang Yang Liu ◽  
...  
Keyword(s):  
Electrical Property ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Growth ◽  
Electrical Characteristics ◽  
Doping Effects ◽  
Zno Varistors ◽  
Doped Zno ◽  
Cu Dopant ◽  
Good Agreement

The doping effects of Cu on the microstructure and non-ohmic electrical properties of ZnO varistors were studied. Addition of Cu2O can enhance the ZnO grain growth during sintering. The SEM and EDS results revealed that the added Cu mainly distributed in the grain boundary and spinel phases of ZnO varistors. The Cu2O addition increased the both of grain and grain boundary resistances. However it decreased the non-ohmic electrical characteristics of ZnO varistors, which is a good agreement with similar findings on Ag2O additions, but contrasts to the reports of good non-ohmic electrical property which found on binary Cu doped ZnO varistors.

scholarly journals Microstructure and Electrical Properties of Low-Voltage Barium Titanate Doped Zinc Oxide Varistor Ceramics

2019 ◽  
Vol 8 (4) ◽  
pp. 2713-2718
Keyword(s):  
Zinc Oxide ◽  
Electrical Properties ◽  
Barium Titanate ◽  
Grain Boundary ◽  
Barrier Height ◽  
Current Density ◽  
Low Voltage ◽  
X Ray ◽  
Highly Nonlinear ◽  
Zno Varistors

In the present, varistor ceramics through the combination of zinc oxide (ZnO) with a perovskite material have become widespread because of their unique properties for a wide range of applications in electronic protection devices. Low-voltage zinc oxide (ZnO) varistors with fast response and highly nonlinear electrical properties for overvoltage protection in an integrated circuit are increasingly significant in the application of low-voltage electronics. The present study highlights the interaction between barium titanate (BaTiO3 ) and ZnO varistors through the employment of solid-state reaction method in the production of low-voltage varistors. The effects of BaTiO3 on the microstructure of ZnO varistors were analyzed through scanning electron microscopy (SEM), energy dispersive X-ray analysis spectroscopy (EDS) and X-ray diffraction (XRD). The EDS analysis and XRD measurements suggest the presence of ZnO and BaTiO3 phases. The electrical properties of BaTiO3 -doped ZnO varistors were examined based on the current density-electric field (J-E) characteristics measurement. The varistor properties showed the nonlinear coefficient (α) from 1.8 to 4.8 with the barrier height (φB) ranged from 0.70 to 0.88 eV. The used of BaTiO3 additive in ZnO varistors produced varistor voltages of 4.7 to 14.1 V/mm with the voltage per grain boundary (Vgb) was measured in the ranges 0.03 to 0.05 V. The lowest leakage current density was 348 µA/cm2 , obtained at the samples containing 12 wt.% BaTiO3 with high barrier height. The reduction in barrier height with increasing BaTiO3 content was associated with the excessive amount of BaTiO3 phase, hence cause the deterioration of active grain boundary due to the variation of oxygen (O) vacancies in the grain boundary.

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.

scholarly journals Grain boundary effects on piezoelectric properties of the core–shell-structured BaTiO3@TiO2 ceramics

2018 ◽  
Vol 08 (06) ◽  
pp. 1850044 ◽  
Author(s):  
Xixi Li ◽  
Zhonghua Yao ◽  
Juan Xie ◽  
Zongxin Li ◽  
Hua Hao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Boundary Effect ◽  
Ferroelectric Properties ◽  
Critical Role ◽  
Impedance Analysis ◽  
Ferroelectric Materials ◽  
Boundary Effects ◽  
Grain Boundary Effects ◽  
Grain Boundary Effect

Grain boundary effect on BaTiO3 has been widely investigated for several decades. However, all of them tailored the grain boundary by grain size of BaTiO3. In this case, a direct way was introduced to modify the grain boundary by coating technique to investigate the role of grain boundary in ferroelectric materials. Nonferroelectric phase TiO2 was employed to investigate grain boundary effects on the electrical properties of BaTiO3 piezoelectric ceramics. TiO2 coating can result in the reduction of piezoelectric and ferroelectric properties and the annealing process in oxygen can increase piezoelectric behavior of pure BaTiO3 due to valence state of Ti ions while that remains for Ti-modified composition possibly due to the increased grain boundary effect by impedance analysis. Compared with ferroelectric grain, grain boundary plays a critical role to impact the electrical properties of perovskite-type ferroelectric materials.

Effects of Thermal Annealing for Barium and Silicon-Added Bismuth Based Zinc Oxide Varistors on Electrical Properties and Grain Boundary Structure

2013 ◽  
Vol 582 ◽  
pp. 218-221
Author(s):  
Atsuko Kubota ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Thermal Annealing ◽  
Boundary Structure ◽  
Zno Varistor ◽  
Electrical Degradation ◽  
Grain Boundary Structure ◽  
Zno Varistors ◽  
Short Time ◽  
Zinc Oxide Varistors

In order to fabricate varistors with low varistor voltage, the effects of thermal annealing of CoMnBaSi-added Bi based ZnO varistors on electrical properties and the grain boundary structure were investigated. The varistor voltage for the BiCoMnBaSi-added ZnO varistor decreased in half by thermal annealing for a short time. The resistance to electrical degradation was most improved by the addition of SiO2and thermal annealing for 1020 min. It is suggested that the composition of Bi and Si in the sheet-like deposit is changed by varying the annealing time and the resistance to electrical degradation is improved by both addition of SiO2as well as thermal annealing for short time.

ELECTRICAL PROPERTIES OF AlGaN/GaN HETEROSTRUCTURE FIELD-EFFECT TRANSISTORS (HFETs) WITH AND WITHOUT Mg-DOPED CARRIER CONFINEMENT LAYER

2010 ◽  
Vol 09 (04) ◽  
pp. 263-267
Author(s):  
A. Sh. HUSSEIN ◽  
Z. HASSAN ◽  
H. ABU HASSAN ◽  
S. M. THAHAB
Keyword(s):  
Electrical Properties ◽  
Leakage Current ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Carrier Confinement ◽  
Heterostructure Field Effect Transistors ◽  
Gan Heterostructure ◽  
Good Agreement ◽  
Mg Doped

AlGaN/GaN -based heterostructure field-effect transistors (HFETs) with and without Mg -doped semi-insulating carrier confinement layer were simulated by using ISE TCAD software, respectively. The detailed study on the electrical properties of these samples was performed. The effect of inserting Mg -doped GaN layer on the source–drain (S–D) leakage current was investigated. Higher values of drain current and extrinsic transconductance were achieved with conventional HFETs (without Mg -doped). The source-to-drain (S–D) leakage current of conventional HFETs was also higher. However, the S–D leakage current was reduced with the insertion of the Mg -doped semi-insulating carrier confinement layer. Our results are in good agreement with the experimental results obtained by other researchers.

Effect of dopant (Nb) concentration on the grain boundary electrical properties of Nb-doped barium titanate

2003 ◽  
Vol 18 (1) ◽  
pp. 88-96 ◽  
Author(s):  
Seok-Hyun Yoon ◽  
Hwan Kim
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Energy Levels ◽  
Defect Mode ◽  
Impedance Analysis ◽  
Interface State ◽  
Oxygen Adsorption ◽  
State Density ◽  
Coarse Grained

A series of coarse-grained BaTiO3 specimens with different dopant (Nb) concentrations were prepared by adjusting the oxygen partial pressure during sintering. They were again heat-treated in air, and the behavior of the grain boundary electrical properties with the increase of Nb concentration was investigated under the conditions of the same microstructure and heat treatment. The interface states of the grain boundaries were estimated using the grain boundary R (resistance) and C (capacitance) values at each temperature that were obtained from impedance analysis. An increase in the interface state density at certain energy levels with increasing Nb concentration was verified experimentally. One type of interface state was observed for specimens with low Nb concentrations and another for specimens with high Nb concentrations. It is proposed that the changes in the interface state with increasing Nb concentration are related to the transition of the compensating defect mode and differences in the extent of oxygen adsorption at the grain boundaries.

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 Correlation between chemical composition of the γ-Bi2O3 phase and the properties of ZnO varistors

2005 ◽  
Vol 11 (4) ◽  
pp. 169-172 ◽  
Author(s):  
Zorica Brankovic ◽  
Goran Brankovic ◽  
Dejan Poleti ◽  
Ljiljana Karanovic ◽  
Jose Varela
Keyword(s):  
Phase Composition ◽  
Chemical Composition ◽  
Electrical Properties ◽  
Leakage Current ◽  
Diffusion Processes ◽  
Lattice Constants ◽  
Eds Analysis ◽  
Phase Spinel ◽  
Zno Varistors

Four varistor samples differing in chemical and phase composition of the starting Bi2O3 phase were prepared by the method of direct mixing of the constituent phases (DMCP), i.e. by sintering the mixture of the previously prepared phases. The compositions of the constituent phases in the sintered samples were investigated by changes of their lattice constants and by EDS analysis. After sintering, the phase compositions of all the investigated samples were the same: ZnO phase, spinel and ?-Bi2O3. It was found that the ?-Bi2O3 phase was mainly stabilized with Zn2+ ions. All the samples showed good electrical properties with non-linearity coefficients up to 50 and small values of the leakage current. The electrical properties of the samples were discussed in terms of diffusion processes and the redistribution of additives during sintering.

scholarly journals Structural and electrical properties of Ti doped α-Fe2O3

2013 ◽  
Vol 45 (3) ◽  
pp. 281-292 ◽  
Author(s):  
M.V. Nikolic ◽  
D.L. Sekulic ◽  
N. Nikolic ◽  
M.P. Slankamenac ◽  
O.S. Aleksic ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Relaxation Process ◽  
Equivalent Circuit ◽  
Impedance Analysis ◽  
Eds Analysis ◽  
Structural And Electrical Properties ◽  
Ti Doping ◽  
Boundary Contribution

In this work we have analyzed the effects of Ti doping on structural and electrical properties of ?-Fe2O3. When the amount of added Ti (5 wt.%TiO2) was within the solubility degree and XRD, SEM and EDS analysis revealed a homogenous hematite structure, with lattice parameters a= 5.03719(3) ?, c=13.7484(1) ? slightly increased due to incorporation of Ti into the rhombohedral hematite lattice. Higher amounts of Ti (10 wt.%TiO2) resulted in the formation of pseudobrookite, besides hematite, confirmed by SEM and EDS analysis. Studies of electric properties in the temperature range 25-225oC at different frequencies (100 - 1Mz) showed that Ti doping improved electrical conductivity. Impedance analysis was performed using an equivalent circuit, showing one relaxation process and suggesting dominant grain boundary contribution.

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