Analysis of Grain-Boundary in SrCoO3–Doped ZnO Varistors and its Electrical Characteristics

2013 ◽  
Vol 582 ◽  
pp. 181-184 ◽  
Author(s):  
Eiichi Koga ◽  
Masayuki Hogiri ◽  
Yoshiko Higashi
Keyword(s):  
Grain Boundary ◽  
Schottky Barrier ◽  
Boundary Region ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Hetero Structure ◽  
Characteristic Behavior ◽  
Zno Varistors ◽  
Doped Zno ◽  
Barrier Model

The grain-boundary and its electrical characteristics in SrCoO3doped ZnO varistors were studied. The grain-boundary around ZnO-grain is probably composed of SrCoO3, and its electrical behavior is clearly different from two conventional types of Bi-and Pr-based ZnO varitors. The non-linearity and characteristic behavior could be explained by considering the n-p-n hetero-structure at the grain boundary. SrCoO3 in the grain-boundary region should play crucial roles of not only the appearance of non-liner property but also the formation of different hetero-structure from double Schottky-barrier model on conventional 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.

Effects of cobalt doping on the electrical characteristics of Al-doped ZnO varistors

2010 ◽  
Vol 64 (9) ◽  
pp. 1081-1084 ◽  
Author(s):  
Wangcheng Long ◽  
Jun Hu ◽  
Jun Liu ◽  
Jinliang He
Keyword(s):  
Electrical Characteristics ◽  
Cobalt Doping ◽  
Zno Varistors ◽  
Doped Zno

Effect of Al concentration in grain and grain boundary region of Al-doped ZnO films: a dielectric approach

2007 ◽  
Vol 41 (2) ◽  
pp. 025307 ◽  
Author(s):  
S Mandal ◽  
H Mullick ◽  
S Majumdar ◽  
A Dhar ◽  
S K Ray
Keyword(s):  
Grain Boundary ◽  
Boundary Region ◽  
Zno Films ◽  
Doped Zno

Effect of Si and Ba Addition on ZnO Grain Growth and Electrical Characteristics of Bi-Based ZnO Varistors

2013 ◽  
Vol 566 ◽  
pp. 219-222 ◽  
Author(s):  
Atsuko Kubota ◽  
Ai Fukumori ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Electrical Characteristics ◽  
Electrical Degradation ◽  
Zno Varistors

With the goal of fabricating varistors with low varistor voltages, we investigated the effects of adding Ba and Si to BiCoMn-added ZnO varistors on the varistor voltage and the resistance to electrical degradation. Ba2Mn3O8, which reduces the resistance to electrical degradation, was not formed at the grain boundary when Si was added. The resistance to electrical degradation was considerably improved by adding 0.10.15 mol% Si relative to samples to which small amounts of Sb had been added. The varistor voltage increased monotonically with increasing amount of added Si; it was approximately 36 V/mm for 0.1 mol% Si.

Effect of La2O3 on the Microstructure and Electrical Properties of (Ti,Sn)O2 Varistor Ceramics

2010 ◽  
Vol 152-153 ◽  
pp. 1391-1394
Author(s):  
Mao Hua Wang ◽  
Gang Li ◽  
Chao Yao
Keyword(s):  
Electrical Properties ◽  
Grain Boundary ◽  
Experimental Evidence ◽  
Low Voltage ◽  
Nonlinear Coefficient ◽  
Electrical Characteristics ◽  
Electrical Behavior ◽  
Optimal Doping ◽  
Nonlinear Properties ◽  
Ceramic Sintering

(Ti,Sn)O2 varistors doped with different amount of La2O3 were obtained by ceramic sintering processing at 1250 . The effect of La2O3 on the microstructure and nonlinear electrical behavior of the (Ti,Sn)O2 ceramics were investigated. The ceramics have nonlinear coefficients of α=6.2–8.5. Experimental evidence shows that small quantities of La2O3 improve the nonlinear properties of the samples significantly. It was found that an optimal doping composition of 1.0mol% La2O3 leads to a low breakdown voltage of 18.1V/mm, a high nonlinear coefficient of 8.5, which is consistent with the highest and narrowest grain boundary barriers of the ceramics.In view of these electrical characteristics, the (Ti,Sn)O2 varistors with 1.0mol% La2O3 ceramic is a viable candidate for low voltage varistor devices. The characteristics of the ceramics can be explained by the effect of the substitution of La3+ for Ti4+ or Sn4+.

Relation Between Grain Boundary and Electrical Degradation of ZnO Varistors

2006 ◽  
Vol 320 ◽  
pp. 117-120 ◽  
Author(s):  
Masayuki Takada ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Boundary ◽  
Optical Microscopy ◽  
Xrd Analysis ◽  
Twin Plane ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrical Degradation ◽  
Characteristics Analysis ◽  
Zno Varistors ◽  
Doped Zno

The effects of the electrical degradation characteristics and microstructure of Sb2O3-doped ZnO varistors were investigated by optical microscopy, X-ray diffraction (XRD) analysis, and voltage-current (V-I) characteristics analysis. The nonlinearity index α of the V-I characteristics of the Bi-Mn-Co-Sb2O3-doped ZnO varistors decreased with increasing Sb2O3 content after electrical degradation. The twin crystal of ZnO was formed by doping with Sb2O3. The number of twin crystals, of which two c-axes are perpendicular to the twin plane, increased and the number of twin crystals, of which c-axes are parallel to the twin plane, decreased with increasing amount of Sb2O3 doped. It is suggested that electrical degradation is affected by the combination of the orientation of ZnO grains containing twin planes and a double Schottky barrier may not be formed in the twin plane.

Microwave Sintering of ZnO Varistor Ceramics

1992 ◽  
Vol 269 ◽  
Author(s):  
Lionel M. Levinson ◽  
Holly A. Comanzo ◽  
William N. Schultz
Keyword(s):  
Grain Boundary ◽  
Microwave Sintering ◽  
Boundary Effects ◽  
Electrical Behavior ◽  
Careful Evaluation ◽  
Electronic Ceramics ◽  
Zno Varistor ◽  
Conventional Sintering ◽  
Systematic Shift ◽  
Zno Varistors

ABSTRACTZnO varistors are electronic ceramics whose electrical behavior is dominated by grain boundary effects. A careful evaluation of the effect of microwave sintering compared to conventional sintering revealed no significant differences between varistor devices processed by these two methods. A slight apparent enhancement of grain growth was observed for microwave processing, but further evaluation of this effect leads us to believe that it arises from a small systematic shift in temperature derived from the different experimental configurations.

Atmosphere effects in the grain boundary region of ZnO varistors

1984 ◽  
Vol 3 (3) ◽  
pp. 213-216 ◽  
Author(s):  
A. M. R. Senos ◽  
J. L. Baptista
Keyword(s):  
Grain Boundary ◽  
Boundary Region ◽  
Zno Varistors
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