Structural and electronic characteristics of pure and doped ZnO varistors

In this paper, the influences of MnO2 and V2O5 on the varistor properties of ZnO- V2O5-based ceramics were examined. The results show that, the addition of MnO2 to the ZnO-V2O5-based ceramics was found to improve varistor properties. The sintered temperature was benefit to enhancing the growth of crystals of the samples and the non-ohomic coefficient can be improved. The samples have non-ohmic coefficient α=27.8 and varistor voltage U1mA=60.9V/mm when they are sintered at 1100°C with 2 hours.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.343-344.160 ◽

2011 ◽

Vol 343-344 ◽

pp. 160-165 ◽

Cited By ~ 1

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.

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

Materials Letters ◽

10.1016/j.matlet.2010.02.019 ◽

2010 ◽

Vol 64 (9) ◽

pp. 1081-1084 ◽

Cited By ~ 35

Author(s):

Wangcheng Long ◽

Jun Hu ◽

Jun Liu ◽

Jinliang He

Keyword(s):

Electrical Characteristics ◽

Cobalt Doping ◽

Zno Varistors ◽

Doped Zno

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.582.181 ◽

2013 ◽

Vol 582 ◽

pp. 181-184 ◽

Cited By ~ 2

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.

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Quantitative Icts Measurement of Interface States at Grain Boundaries in ZnO Varistors

MRS Proceedings ◽

10.1557/proc-500-213 ◽

1997 ◽

Vol 500 ◽

Author(s):

K. Mukae ◽

A. Tanaka

Keyword(s):

Grain Boundaries ◽

Interface States ◽

Zno Varistors ◽

Single Grain ◽

Doped Zno ◽

Transient Spectroscopy ◽

Er Doped ◽

Capacitance Transient ◽

Rare Earth Doped ◽

Density Of Interface States

ABSTRACTIsothermal capacitance transient spectroscopy(ICTS) measurement is applied to ZnO:Pr varistors. A simple peak corresponding to the interface states at grain boundaries was obtained and the energy level of the interface states revealed to be monoenergetic and located around 0.9eV below the conduction band. The cross section was calculated as around 10−14 cm2. Quantitative treatment of the ICTS intensity in relation to the density of interface states at grain boundaries was established. The density of interface states was obtained from the linear relation between ICTS intensity and reciprocal carrier density(ND). According to experiments on series of rare-earth doped ZnO varistors, the interface states of Pr, Tb or Nd doped ZnO varistors had higher density of states than La or Er doped varistors. Moreover, application of ICTS measurement to single grain boundary using microelectrodes revealed that higher density of interface states gave higher nonlinearity in I-V characteristics.

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