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

Long, Wangcheng; Hu, Jun; Li, Jun; He, Jinliang

doi:10.1016/j.matlet.2010.02.019

Cited by 51 publications

(28 citation statements)

References 10 publications

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“…It is well-established that the addition of cobalt oxides in the matrix of ZnO improves the non-linear properties Long et al 2010;Nahm and Kim 2002;. found that, the ZnO-CoO-based varistor, with an average grain size of 16 lm, have an ohmic behavior at low sintering temperatures (below 1,000°C), and also at high sintering temperatures (above 1,100°C).…”

Section: Introductionmentioning

confidence: 99%

“…Unfortunately, they did not calculate the values of the nonlinearity coefficient a, which has been investigated in this study. Several studies Long et al 2010;Cheng et al2012;Anas et al 2010) have investigated the properties of ZnO, doped with different elements-based varistors using various methods, but few works have been devoted to study the properties of ZnO-CoO-based varistors, especially, using the microwave sintering on one hand and to use nanocrystalline powders for manufacturing pellets used for this study on the other hand; it is what gives this study its originality, in which we investigated the influence of grain size and amount of Co on the properties of ZnO-CoO-based varistors.…”

Section: Introductionmentioning

confidence: 99%

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The effect of the starting powders particle size on the electrical properties of sintered Co doped ZnO varistors

Hamdelou¹,

Guergouri

Arab

2014

Appl Nanosci

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Pure and Co doped zinc oxide nanopowders have been synthesized by sol-gel route. The obtained powders, after calcination in air at 550, 650, 750 and 850°C, were consolidated and sintered using microwaves. The effect of sintering temperature on the density and electrical properties was investigated. The best characteristics are obtained using a sintering temperature equal to 1,075°C. The powders and sintered samples are characterized by X-ray diffraction, microstructure images, density and electrical measurements. The studied nanopowders have: a density of 5.22 (g/cm 3 ), a breakdown voltage of 446.5 V/mm and a coefficient of non-linearity of 11.48 for ZnO doped with 7 mol% Co, and a density of 5.19 (g/cm 3 ), a breakdown voltage of 292.5 V/mm and a non-linearity coefficient of 11.62 for ZnO doped with 5 mol% Co. The XRD results indicate that pure and Co doped ZnO powders are solid solutions crystallizing in pure würtzite structure, and consisted of a mixture of nanoparticles with an average grain size between 36 and 210 nm. The grain size decreases with increasing Co concentration and reaches its lowest value at 7 mol% Co and increases with increasing temperature. On the other hand the increase of Co concentration leads to a decrease of the porosity and an increase of the density of samples sintered at 1,070°C and leads also to an increase of the electric field (E) in the nonlinear area. The samples of 5 mol% Co sintered at 1,075°C, show that the non-linear coefficient a decreases by increasing of calcined temperature, therefore increases with decreasing of grain and particle sizes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of the starting powders particle size on the electrical properties of sintered Co doped ZnO varistors

Hamdelou¹,

Guergouri

Arab

2014

Appl Nanosci

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“…In previous works, we have sintered the ZnO varistors samples with various Al doped, and we find out that the donor density of the samples with 0.25 mol% Al ionic doped arrive to maximum 5.71×10 23 cm -3 [10]. The effects of Co 2 O 3 on electrical characteristics of 0.25mol% Al-doped ZnO varistor are studied, we arrived at the conclusion that while the ZnO varistors with 3 mol% to 4 mol% Co 2 O 3 doped, the leakage currents of the samples are inhibited, and their nonlinear coefficients increase remarkably [11].…”

Section: Introductionmentioning

confidence: 83%

Effect of Bi<inf>2</inf>O<inf>3</inf> doping on the electrical characteristics of Al-doped ZnO varistors with low residual voltage

Long

et al. 2010

2010 Annual Report Conference on Electrical Insulation and Dielectic Phenomena

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The effects of Bi 2 O 3 doping on the electrical characteristics of Al-doped ZnO varistors were studied. The electrical characteristics and the microstructural parameters of the varistor samples with various content of Bi 2 O 3 additive were investigated. With the amount of the doped Bi 2 O 3 increased, the leakage currents of the Al-doped ZnO varistors are inhibited obviously. In addition, their breakdown electric fields decrease and their nonlinear coefficients increase accordingly. The XRD patterns show that the Bi-rich phase changes remarkably in the varistor samples as the delta-Bi 2 O 3 are decreasing and the BiO 2-x phase are increasing. The effects of Bi 2 O 3 doping on the electrical characteristics of the Al-doped ZnO varistors are discussed based on the XRD patterns.

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“…In previous work, we found out that the donor densities of the samples doped with 0.25 mol% Al ionic gained the maximum value of 5.7110 23 cm -3 [11]. The effects of Co 2 O 3 additives on the electrical characteristics of ZnO varistors doped with 0.25mol% Al have been studied, from which we drew the conclusion that while ZnO varistors were doped with 3 mol% to 4 mol% Co 2 O 3 , the leakage currents of the samples could be inhibited, and their nonlinear coefficients would increase remarkably [12].…”

Section: Introductionmentioning

confidence: 99%

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

Cited by 51 publications

References 10 publications

The effect of the starting powders particle size on the electrical properties of sintered Co doped ZnO varistors

The effect of the starting powders particle size on the electrical properties of sintered Co doped ZnO varistors

Effect of Bi<inf>2</inf>O<inf>3</inf> doping on the electrical characteristics of Al-doped ZnO varistors with low residual voltage

Effects of manganese dioxide additives on the electrical characteristics of Al-doped ZnO varistors

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