Degradation in ZnO varistors

Castro, M. S.; Benavente, Micaela Andrea; Aldao, C. M.

doi:10.1088/0953-8984/5/33a/125

Cited by 9 publications

(3 citation statements)

References 3 publications

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“…10 The importance of spin density waves was shown to be substantial for high-temperature superconductivity. [11][12][13][14] A question to be answered is the role of phonons in the process of high-temperature superconductivity in these oxides. We have tried to answer this question by doping Cd at the CuO 2 planar sites in Cu 0.5 Tl 0.5 Ba 2 Ca 3 (Cu 4-y Cd y )O 12-δ (y=0.5, 1, 1.5, 2).…”

Section: Introductionmentioning

confidence: 99%

Suppression of Superconductivity by Anharmonic Oscillations in Zn- or Ni-doped Cu0.5Tl0.5Ba2(CaMg)Cu1.5M1.5O10-δ (M=Zn, Ni) Superconductors; Evident by Magnetic Measurements

Safeer

Raza

Khan

et al. 2021

J. Electron. Mater.

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An inter-comparison of the superconducting properties of Cu 0.5 Tl 0.5 Ba 2 (CaMg)Cu 3 O 10-δ and Cu 0.5 Tl 0.5 Ba 2 (CaMg) Cu 1.5 M 1.5 O 10-δ (M = Zn, Ni)-doped samples was undertaken. Our main objective was to determine the role of electron-phonon interactions in the mechanism of high-temperature superconductivity in these oxide superconductors. We achieved this goal indirectly by doping Zn and Ni at the Cu sites in this compound. The replacement of Cu with Zn/Ni atoms induced anharmonic oscillations due to the difference in their masses. The influence of anharmonic oscillations was enhanced due to the decreased distance between the conducting CuO 2 /MO 2 (M = Zn, Ni) planes. A comparison of zero-field-cooled (ZFC) and field-cooled (FC) magnetic moments showed suppression in the magnitude of diamagnetism with doping of Zn and Ni atoms. We suggest that the suppression in the magnetic moments arises from the difference in the atomic mass of the doped atoms in comparison with Cu atoms. With doping of Zn and Ni, the width of the magnetic hysteresis loops and their critical current density are suppresses. These decreased values in the doped samples give rise to huge anharmonic oscillations that suppress the population of phonons necessary for the mechanism of electron-phonon interactions Keywords Cu 0.5 Tl 0.5 Ba 2 (CaMg)Cu 1.5 M 1.5 O 10-δ (M=Zn, Ni) samples • infield magnetic measurements • anharmonic oscillations • electron-phonon interactions • high-temperature superconductors * Syed Hamza Safeer

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Section: Introductionmentioning

confidence: 99%

Suppression of Superconductivity by Anharmonic Oscillations in Zn- or Ni-doped Cu0.5Tl0.5Ba2(CaMg)Cu1.5M1.5O10-δ (M=Zn, Ni) Superconductors; Evident by Magnetic Measurements

Safeer

Raza

Khan

et al. 2021

J. Electron. Mater.

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“…[1][2][3][4][5][6][7] As a mechanism and search of ways to improve the stability of ZnO varistors against degradation are practically important problems. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The general concepts of a deformation of the grainboundary potential barriers (a decrease in their height and width due to a movement result of dc degradation, the asymmetry of current-voltage characteristics appears. [1][2][3][4][5] The understanding of degradation of some ions in electric field) are the physical basis for the interpretation of this effect.…”

Section: Introductionmentioning

confidence: 99%

Percolation effects in dc degradation ofZnOvaristors

2015

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For quantitative estimation of the degree of electrical disorder (electrical inhomogeneity) in ZnO varistor ceramics caused by a variation in the barrier height at different grain boundaries in a sample, the comparison of threshold electric fields (onsets of highly nonlinear current-voltage characteristics) in ceramics and single grain boundary (GB) is suggested and approved. At dc degradation similar behavior of the current-voltage characteristics of ZnO varistor ceramics and single GB is observed. The percolation model of Shklovskii-De Gennes is applicable for the description of a disorder in ZnO varistor ceramics. The degree of the disorder in ZnO varistor ceramics is not dependent on the duration of dc degradation at least at degradation time below 60 h. At voltages close to the onset of a highly nonlinear region of current-voltage characteristic the correlation radius of infinite cluster is $ 5 times greater than the average grain size.

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“…On the one side it is theoretical problems of studies of nonlinear conductivity of varistor ceramic which is considered as disordered system of many "microvaristors" (Tonkoshkur, 1990a;Bartkowiak et al, 1996b;Nan and Clarke 1996;Vojta and Clarke, 1997;Nan et al, 2001). On the other side it is technological problems of prediction and control of nonlinearity of the varistor ceramic, as well as stability and reproducibility of varistor properties (Gupta, 1990;Castro et al, 1993;Tonkoshkur et al, 1995;Clarke, 1999;Glot and Mazurik, 2000;Ivanchenko et al, 2004;Tada, 2010;Ivanchenko and Tonkoshkur, 2012).…”

Section: Introductionmentioning

confidence: 99%

Modeling of current-voltage characteristic of the intergranular barrier in metal oxide varistor ceramics

Тонкошкур

Иванченко

2014

Multidiscipline Modeling in Materials and Structures

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Purpose -The purpose of this paper is to develop a generalized model of the nonlinear conductivity of varistor ceramic suitable for solving problems of prediction and control of ceramic nonlinearity, stability of varistor properties. Design/methodology/approach -The modeling of current-voltage characteristic of the intergranular barrier in metal oxide varistor ceramics is based on the development of the algorithm. It includes all the known mechanisms of electrotransfer in a wide range of voltages and currents of the current-voltage characteristics, and also takes into account the deviation of the barrier form the Schottky barrier. Findings -The models of double Schottky barrier and double barrier of arbitrary form, as well as the algorithms for calculating the current-voltage characteristics of a single intergranular potential barrier and a separate "microvaristor" with the use of the most well-established understanding of the main mechanisms of electrical are developed. The results of current-voltage characteristics modeling correspond to the existing understanding of the nonlinear electrical conductivity varistor ceramics are based on zinc oxide. The model of double barrier of arbitrary form takes into account the deviation of the barrier form the Schottky barrier which is important in predicting the deformation of the current-voltage characteristics of the varistor products in the process of degradation. Originality/value -The relation between the form of the current-voltage characteristic and the distribution profile of the donor concentration in the surface regions of the semiconductor crystallites constituting the intergranular potential barrier is established. The accumulation of donors in the space charge region leads to the increase in the current on the prebreakdown region of the current-voltage characteristic and the reduction of voltage corresponding to the breakdown region beginning of the current-voltage characteristic. The significant role of the interlayer in the formation of current-voltage characteristic of the intergranular potential barrier is shown.

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Degradation in ZnO varistors

Cited by 9 publications

References 3 publications

Suppression of Superconductivity by Anharmonic Oscillations in Zn- or Ni-doped Cu0.5Tl0.5Ba2(CaMg)Cu1.5M1.5O10-δ (M=Zn, Ni) Superconductors; Evident by Magnetic Measurements

Suppression of Superconductivity by Anharmonic Oscillations in Zn- or Ni-doped Cu0.5Tl0.5Ba2(CaMg)Cu1.5M1.5O10-δ (M=Zn, Ni) Superconductors; Evident by Magnetic Measurements

Percolation effects in dc degradation ofZnOvaristors

Modeling of current-voltage characteristic of the intergranular barrier in metal oxide varistor ceramics

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