Nonlinear Electrical Properties of (Sc, Ta) Doped TiO2 Varistor Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 289-292 ◽  
Author(s):  
Wen Bin Su ◽  
Jin Feng Wang ◽  
Hong Cun Chen ◽  
Guo Zhong Zang ◽  
Peng Qi ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Crystal Lattice ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Donor Concentration ◽  
Varistor Ceramic ◽  
Electrical Field ◽  
Schottky Type ◽  
Zno Varistors

The nonlinear electrical properties of TiO2-based varistor doped with 0.25mol% Ta2O5 and different contents of Sc2O3 were investigated. It was found that the TiO2 varistor ceramic doped with 0.10mol% Sc2O3 exhibited an optimal nonlinear coefficient of 7.8, a breakdown electrical field of 16.0V/mm, and relative dielectric constant of 1.27 × 105 (measured at 1 kHz). In order to analyze the effect of Sc2O3 on TiO2 varistors, studies were made on the capacitance versus voltage characteristics. A Schottky-type barrier, which is assumed as the origin of varistor behavior, was inferred from the C-V measurement. The barrier height and donor concentration were obtained as 0.41eV and 1.21 × 1026cm-3, respectively, for sample doped with 0.10mol% Sc2O3. Analogized to the ZnO varistors, the formation mechanism of Schottky-type barrier was discussed in this paper by the theory of defect in crystal lattice.

High Permittivity and Varistor Properties of SnO2-Zn2SnO4 Composite Ceramics

2014 ◽  
Vol 670-671 ◽  
pp. 121-126
Author(s):  
Huan Huan Liu ◽  
Li Ben Li ◽  
Guo Zhong Zang ◽  
Jing Xiao Cao ◽  
Yong Li
Keyword(s):  
Dielectric Constant ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Electrical Current ◽  
Schottky Barriers ◽  
Composite Ceramics ◽  
Electrical Field ◽  
Dielectric Peak ◽  
High Dielectric ◽  
40 Hz

(1-x)SnO2-xZn2SnO4composite ceramics were prepared by traditional ceramic processing and the varistor, dielectric properties were investigated. With increasing Zn2SnO4content, the breakdown electrical fieldEBand nonlinear coefficientαreaches the minimum of 6.9 V/mm and 2.5 at x=0.206, respectively. In the dielectric spectra, the relative dielectric constantεrexhibits strong frequency dependent character and at 40 Hz,εrfor the sample of x=0.206 reaches a maximum as high as 3×104. In the frequency region lower than 1 kHz, accompanied by the sharp increase of dielectric loss at 40 Hz,εris depressed and a dielectric peak is presented in the spectra with increasing bias voltage. In the low electrical current range of 1.37-20 μA, The barrier heightφBabout 1.0 eV are obtained and it is found thatφBdecreases with increasing measuring current for each sample. Based on the results, the varistor behavior with high dielectric constant is explained by the Schottky barriers at grain boundaries.

Effect of TiO2 Nano Powder on the Microstructure and Electrical Properties of TiO2 Capacitor-Varistor Ceramics

2011 ◽  
Vol 341-342 ◽  
pp. 94-97
Author(s):  
Tian Guo Wang ◽  
Qun Qin ◽  
Wen Jun Zhang
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Breakdown Voltage ◽  
Nonlinear Coefficient ◽  
Relative Dielectric Constant ◽  
Optimal Composition ◽  
Low Loss ◽  
Nano Powder

The influence of TiO2 nano powder on the electrical properties and microstructure of TiO2 ceramics was studied. The results showed that nano additive reduces the size of TiO2 grain. The results also showed that the breakdown voltage and nonlinear constant of the samples were improved and the dielectric constant was reduced by doping nano-titania. An optimal composition dopant with 6 mol% nano-titania exhibited a low breakdown voltage of 11.3 V/mm, a nonlinear coefficient of 5.5, an ultrahigh relative dielectric constant of 7.11×104 and relatively low loss of 0.28.

Effect Of Moisture On The Physical Properties Of Polyimide Films

1991 ◽  
Vol 227 ◽  
Author(s):  
Rajeevi Subramanian ◽  
Michael T. Pottiger ◽  
Jacqueline H. Morris ◽  
Joseph P. Curilla
Keyword(s):  
Dielectric Constant ◽  
Steady State ◽  
Electrical Properties ◽  
Relative Humidity ◽  
Quartz Crystal ◽  
Moisture Absorption ◽  
Relative Dielectric Constant ◽  
Moisture Uptake ◽  
Polyimide Films ◽  
Effect Of Moisture

ABSTRACTMoisture absorption and its effect on electrical properties were measured for several polyimides. A Quartz Crystal Microbalance (QCM) was used to investigate the moisture absorption in BPDA/PPD, PMDA/ODA, and BTDA//ODA/MPD polyimides. The steady-state moisture uptake in polyimides as a function of relative humidity (RH) was determined by exposing film samples to successively higher RH values ranging from 10 to 85% at 25°C. The isothermal moisture absorption as a function of percent RH was found to be nearly linear for all of the polyimides studied. The effect of moisture on the electrical properties of a BPDA/PPD polyimide was also investigated. The relative dielectric constant at 25 °C was found to be a linear function of the moisture absorbed.

Performance of (Y2O3,V2O5) Co-Doping TiO2 Ceramics

2016 ◽  
Vol 697 ◽  
pp. 271-274
Author(s):  
Gui Min Jiang ◽  
Ji Kang Yan ◽  
Gang Yang ◽  
Zhi Cao Duan ◽  
Kun Yong Kang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Sintering Temperature ◽  
Nonlinear Coefficient ◽  
Electrical Performance ◽  
Varistor Ceramic ◽  
Co Doping

The present study investigated the effect of the sintering temperature and (Y2O3, V2O5) co-doping on the performance of TiO2 varistor ceramic which has lower varistor voltage and high nonlinear coefficient. The results showed that the TiO2-based varistor ceramic which doped with 0.35% mol and 0.25% mol of Y2O3 and V2O5 has good comprehensive electrical performance and excellent dielectric constant sintered at 1200°C. Its varistor voltage V1mA is 38.1V, nonlinear coefficient is 4.6.

Effect of Fe2O3 Dopant on Electronic Densities and Electrical Properties of ZnO-Based Varistors

2011 ◽  
Vol 415-417 ◽  
pp. 1042-1045
Author(s):  
Wen Deng ◽  
Zhen Quan Lei ◽  
Jiao Ling Zhao ◽  
Yan Qiong Lu ◽  
Ding Kang Xiong
Keyword(s):  
Electrical Properties ◽  
Positron Lifetime ◽  
Nonlinear Coefficient ◽  
Doppler Broadening ◽  
Donor Concentration ◽  
Current Voltage ◽  
Electronic Densities ◽  
Current Voltage Characteristics ◽  
Doppler Broadening Spectra ◽  
Coincidence Doppler Broadening

The effect of the Fe2O3dopant on the electronic densities and the electrical properties has been studied in a ZnO-Bi2O3-SnO2-Co2O3-MnO2-TiO2-Ni2O3-Fe2O3system by the measurements of positron lifetime spectra, coincidence Doppler broadening spectra and current-voltage characteristics. The results show that the 3d electron signal in the spectrum of the varistor increases with the Fe2O3content. The addition of small amount of Fe2O3into the ZnO-based varistor leads to an increase in the donor concentration in the bulk and the defects in the varistor. As the Fe2O3content increased, the threshold voltage (VT) and the nonlinear coefficient (α) of the varistor decreased monotonously.

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.

Influence of Doped Mn, Cu, Ni and Fe on Electrical Properties of SrTiO3 Ceramics

2009 ◽  
Vol 79-82 ◽  
pp. 1603-1606 ◽  
Author(s):  
Ning Zhang Wang ◽  
Sha Sha ◽  
Yu Tian Ma
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Nonlinear Coefficient ◽  
Lower Dielectric Constant ◽  
Sintering Conditions

MnCO3, CuO, NiO and Fe2O3 doped SrTiO3 multifunction ceramics were fabricated firstly. The microstructure and electrical properties were investigated. The results show that MnCO3 doped ceramic and CuO doped ceramic possess relative higher resistivity (ρ),nonlinear coefficient (α), varistor voltage (V1mA) and relative lower dielectric constant (ε),dielectric loss (tgδ) in contrast with NiO doped ceramic and Fe2O3 doped ceramic with the same contents under the same sintering conditions. The electrical properties among the ceramics doped are different due to the different behaviors of Mn,Cu,Ni and Fe acceptor dopants during the sintering course.

The Role of Niobium in (Ca, Si, Ce, Nb)-Doped TiO2 Varistors

2007 ◽  
Vol 280-283 ◽  
pp. 297-300 ◽  
Author(s):  
Shao Hua Luo ◽  
Zi Long Tang ◽  
Hong Yun Li ◽  
Zhong Tai Zhang ◽  
Xi Zhou Xiong
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Room Temperature ◽  
Structural Characteristics ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Optimal Composition ◽  
Low Loss ◽  
Nb Addition

The present work attempted to investigate the effect of Nb addition on the electrical properties of the (Ca,Si,Ce,Nb)-doped TiO2 ceramics. The content of added niobium is in the range 0.1-1.0mol %, while that of the other additives keeps constant. The results showed that an optimal composition doped with 0.8mol% Nb2O5, followed by sintering at 1350°C, was obtained with low V1 mA of 7.22V, high nonlinear coefficient of 5.76, ultrahigh dielectric constant (er = 86000) as well as relatively low loss (tgd = 0.52) in room temperature at 1 kHz. SEM studies show that change of niobium had significant influence on grain growth and micro structural characteristics of the sintered samples.

Study on Microstructure and Electrical Properties of ZnO Varistor Ceramics

2011 ◽  
Vol 415-417 ◽  
pp. 2008-2011 ◽  
Author(s):  
Chang Qi Xia ◽  
Qi Bin Liu ◽  
Mo He
Keyword(s):  
Electrical Properties ◽  
Sintering Temperature ◽  
Spinel Phase ◽  
Voltage Gradient ◽  
X Rays ◽  
Sintering Process ◽  
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, which were sintered from 1135 to 1155 °C, the microstructure and properties of varistors were characterized by SEM, X-rays diffraction and DC parameter instrument for varistors. The experimental results show that the spinel phase Zn7Sb2O12 generated during sintering process, very thin amorphous Bi rich films are formed between the ZnO/ZnO grain boundaries, 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. The optimized parameters are that 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%, the comprehensive electrical properties of ZnO varistors reach maximum.

Analyses of defect distributions in ZnO varistors based on the Jonscher’s universal power law and the Dissado–Hill model

2021 ◽  
Vol 55 (13) ◽  
pp. 135106
Author(s):  
Xia Zhao ◽  
Men Guo ◽  
Yuandong Wen ◽  
Weidong Shi ◽  
Boyu Zhang ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Power Law ◽  
Current Density ◽  
Nonlinear Coefficient ◽  
Breakdown Field ◽  
Hill Model ◽  
X Ray ◽  
Universal Power Law ◽  
Zno Varistors ◽  
Doped Zno

Abstract The defect distributions in ZnO varistors mixed with Bi2O3, NiO, MnCO3, Co2O3, and SiO2 after doping Sb2O3 were investigated, based on the Jonscher’s universal power law and the Dissado–Hill model. The microstructures were investigated using x-ray diffractometer, scanning electron microscope, energy dispersive spectrometer, and x-ray photoelectron spectrometer. The capacitance–voltage (C–V) method was utilized to obtain the parameters of the double Schottky barrier. The dielectric spectra were analyzed to extract the parameters of defect distribution. The current density–electric field (J–E) characteristics were measured to obtain the parameters of electrical properties. We found that with increasing Sb2O3 content, the ZnO grain size distribution become more homogeneous in the Sb2O3-doped ZnO varistors; the density Zn i × is decreased; except for less homogeneous V O × , more homogeneous distributions of Zn i ∙ in the depletion layers and the extrinsic defects at the interfaces are achieved in the Sb2O3-doped ZnO varistors. Therefore, the enhancement in the electrical properties was achieved by doping Sb2O3 due to the increased number of active grain boundaries per unit volume, i.e. the increased breakdown field and nonlinear coefficient, and the decreased leakage current density. The results of this study suggest that the Jonscher’s universal power law and the Dissado–Hill model can be effectively used to analyze defect distributions in varistor ceramics.

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