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

2011 ◽  
Vol 131 (3) ◽  
pp. 211-218
Author(s):  
Ai Fukumori ◽  
Takayuki Watanabe ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Growth ◽  
Electrical Characteristics ◽  
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.

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 Sb Addition on ZnO Grain Growth and Electrical Characteristics of Bi–Co–Mn–Ba-Added ZnO Varistors

2011 ◽  
Vol 485 ◽  
pp. 253-256 ◽  
Author(s):  
Ai Fukumori ◽  
Takayuki Watanabe ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Electrical Characteristics ◽  
Electrical Degradation ◽  
Zno Varistors

With the goal of fabricating varistors with low breakdown voltages (varistor voltages), the effect of adding Sb to Bi-Co-Mn-Ba-added ZnO varistors on the ZnO grain size was investigated. To obtain a uniform ZnO grain size without reducing the grain size, a small amount (e.g., 0.01 mol%) of Sb was added as an additive. This addition suppresses the variation in the ZnO grain size without reducing the grain size. It also improved the resistance to electrical degradation because compounds of Ba and Mn were not formed.

Influences of Dopants on the Microstructural Nonuniformity of ZnO Varistors

2008 ◽  
Vol 368-372 ◽  
pp. 503-506
Author(s):  
Jin Liang He ◽  
Jun Hu ◽  
Feng Chao Luo
Keyword(s):  
Growth Rate ◽  
Standard Deviation ◽  
Grain Growth ◽  
Linear Relation ◽  
Al2o3 Content ◽  
Electrical Characteristics ◽  
Average Value ◽  
Grain Sizes ◽  
Zno Varistors ◽  
Log Linear

This paper systematically analyzes the microstructural nonuniformity of ZnO varistors when Al2O3 dopants are added. The introduction of Al2O3 dopants leads to a decrease of ZnO grain growth rate and correspondingly an increase of the microstructural uniformity of ZnO varistors. Both the average value and the standard deviation of ZnO grain sizes decrease with the increase of Al2O3 content, approximately in a log-linear relation. With detailed experimental results, this study provides quantitative references for the practice of adding Al2O3 dopants to give ZnO varistors desired microstructural and electrical characteristics.

Effect of Ba Addition on Electrical Characteristics of Bi-Based ZnO Varistors

2010 ◽  
Vol 445 ◽  
pp. 241-244 ◽  
Author(s):  
Ai Fukumori ◽  
Masayuki Takada ◽  
Yuji Akiyama ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Breakdown Voltage ◽  
Electrical Characteristics ◽  
Zno Varistor ◽  
Electrical Degradation ◽  
Poor Tolerance ◽  
Zno Varistors ◽  
Molten Phase

With the goal of fabricating low-breakdown-voltage varistors, the effect of adding Ba to ZnO varistors on the ZnO grain size was investigated. Grain growth of ZnO could be markedly promoted by adding both Ba and Bi. The maximum grain size was approximately 150 μm and the minimum varistor voltage was approximately 12 V/mm. However, it had relatively poor tolerance characteristics for electrical degradation. It is speculated that when adding both Ba and Bi to a Mn–Co-added ZnO varistor, it is necessary to form the molten phases of Ba and Bi to promote grain growth of ZnO. It is also conjectured that the growth of ZnO grains is not promoted when Ba and Bi do not coexist in the molten phase because Ba forms compounds with Mn independently with the addition of small amounts of Bi.

Effect of Simultaneous Addition of Zr and Y on Electrical Characteristics of ZnO Varistors

2011 ◽  
Vol 485 ◽  
pp. 257-260 ◽  
Author(s):  
Takayuki Watanabe ◽  
Ai Fukumori ◽  
Yuji Akiyamna ◽  
Yuuki Sato ◽  
Shinzo Yoshikado
Keyword(s):  
Leakage Current ◽  
Nonlinear Coefficient ◽  
The Other ◽  
Electrical Characteristics ◽  
Simultaneous Addition ◽  
Zno Varistor ◽  
Low Leakage ◽  
Electrical Degradation ◽  
Low Leakage Current ◽  
Zno Varistors

The effect of simultaneously adding Zr and Y to Bi–Mn–Co–Sb–Si–Cr–Ni-added ZnO varistors (having the same composition as a commercial varistor) on the varistor voltage, leakage current, and resistance to electrical degradation were investigated. Varistor voltage increased with increasing amount of Y for addition of 0–2 mol % Zr. On the other hand, the nonlinear coefficient α prior to electrical degradation changed very little on the addition of both Y and Zr. With the addition of approximately 1 mol% Zr, the leakage current decreased with increasing amount of Y added. A ZnO varistor with a varistor voltage of approximately 600 V/m, a low leakage current, and excellent resistance to electrical degradation was fabricated by adding approximately 2 mol% Y and approximately 1 mol% Zr.

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
Sign in / Sign up

Export Citation Format

Share Document