Synthesis, structure and dielectric properties of nanocrystalline SnO2–CoO–Nb2O5 varistor doped with Cr2O3

Desouky, Osama A.; Rady, K. E.

doi:10.1007/s10854-016-6041-9

Cited by 8 publications

(3 citation statements)

References 36 publications

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“…During sintering, Bi 2 O 3 forms a liquid phase and leads to the development of Bi‐rich phases around grains in the varistor. The addition of metal oxides improves the electrical characteristics of basic binary varistors by (a) modulating grain conductivity in the varistor, (b) affecting grain enhancement and secondary phase formation during sintering, (c) forming inversion boundaries between grains, and (d) affecting intergranular phase characteristics (Desouky & Rady, 2017).…”

Section: Introductionmentioning

confidence: 99%

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors

Sendi

2021

Microscopy Res & Technique

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In this research, ZnO–Bi2O3–Mn2O3 varistors manufactured from 20 nm ZnO powder and doped with different amounts of Er2O3 were fabricated via the conventional ceramic processing method. The effect of various Er2O3 concentrations (0.5–2.0 mol%) on the sintered density, structural improvement, and nonlinear behavior of the 20 nm ZnO–Bi2O3–Mn2O3 varistors was discussed. Different Er2O3 concentrations exerted considerable influence on the varistors. The addition of large amounts of Er2O3 led to the inhibition of grain growth by increasing the amount of the Er2O3‐rich spinel phase. X‐ray diffraction analysis showed that the addition of Er2O3 to the varistor systems led to the development of Er2O3‐rich phases during sintering. During sintering, the considerable surface area of the nanoparticle powder resulted in numerous interactions in the surfaces of the ceramics manufactured from 20 nm ZnO powder. The electrical behaviors of the varistors were substantially influenced by Er2O3. E1 mA evidently increased from 2,144.7 to 5,482.2 V/mm with the increment in doping amount. The nonlinear coefficient also dramatically increased with the increase in Er2O3 content. The ZnO nanoparticle–Bi2O3–Mn2O3 varistors doped with 1.0–2.0 mol% Er2O3 possessed high voltage and nonlinearity and were stable against DC‐accelerated aging stress.

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Section: Introductionmentioning

confidence: 99%

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors

Sendi

2021

Microscopy Res & Technique

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“…It is well established that there is a close relationship between microstructure and electrical properties in polycrystalline electroceramics, especially in varistors [1][2][3][4][5][6] -a special class of ceramics presenting a nonlinear relationship between the applied potential and the resulting current [7]. When dealing with varistors, the grain size distribution has a major role determining the breakdown electric field (E b ), i.e., the point at which a small change in the applied voltage generates a large variation in the current passing through the device.…”

Section: Introductionmentioning

confidence: 99%

Coalescence growth mechanism of inserted tin dioxide belts in polycrystalline SnO2-based ceramics

Masteghin

Bertinotti

Orlandi

2018

Materials Characterization

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SnO 2-based varistors have been considered promising technological devices. However their practical application is usually stated as limited to high voltage circuits based on the high breakdown electric field exhibited by these ceramics. Recently, authors have shown that the insertion of one-dimensional (1D) SnO 2 belts allows overcoming this limitation. In this work, we present a detailed study of the growth mechanism of the belts inside varistors using electron microscopy techniques. We were able to show that mass transport has an intrinsic dependence on the sintering time and requires similar crystalline structure between the belts and the matrix. Dual beam and high-resolution transmission electron microscopy techniques permitted determining that 3D growth of belts occurs by coalescence.

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“…SnO 2 is a material that initially presents low density due to the evaporation/ condensation processes at high temperatures. As such, for it to be employed as a varistor (which requires a high degree of densification) one needs to subject it to hot isostatic pressing sintering [5], or doping with other metal oxides with oxidation state inferior to Sn +4 which can promote the formation of oxygen vacancies that are responsible for controlling the mass transport during the sintering [6,7].…”

Section: Introductionmentioning

confidence: 99%

High-performance and low-voltage SnO2-based varistors

Masteghin

Bertinotti

Orlandi

2017

Ceramics International

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This paper presents the results of a thorough study conducted on the action mechanism of one-dimensional single-crystalline SnO 2 nanobelts in decreasing the breakdown electric field (E b) in SnO 2-based varistors. The proposed method has general validity in that our investigation was focused on the traditional varistor composition SnO 2-CoO-Cr 2 O 3-Nb 2 O 5. To accomplish our study objective, two methods of decreasing E b value were compared; one involving the increase in average grain size of the varistor through the sintering time and the other one related to the addition of nanobelts. The morphological results show that the method involving the increase in average grain size is limited by the formation of intragranular pores. Furthermore, despite contributing successfully towards decreasing the E b value (which underwent a decline from 3990 V cm −1 to 1133 V cm −1 with an increase in sintering time from 1 h to 2 h), the reduction obtained by this method is found to be much lower compared to that obtained via the nanobelts insertion method (E b = 270 V cm −1). Impedance spectroscopy results showed that the insertion of nanobelts caused a decline in the grain boundary resistance while surface potential measurements proved that this decline in resistance is attributed to the absence of potential barriers along the belts which leads to the formation of a lower resistance percolation path in the varistor.

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Synthesis, structure and dielectric properties of nanocrystalline SnO2–CoO–Nb2O5 varistor doped with Cr2O3

Cited by 8 publications

References 36 publications

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors

Coalescence growth mechanism of inserted tin dioxide belts in polycrystalline SnO2-based ceramics

High-performance and low-voltage SnO2-based varistors

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Synthesis, structure and dielectric properties of nanocrystalline SnO2–CoO–Nb2O5 varistor doped with Cr2O3

Cited by 8 publications

References 36 publications

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi2O3–Mn2O3‐based varistors

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi2O3–Mn2O3‐based varistors

Coalescence growth mechanism of inserted tin dioxide belts in polycrystalline SnO2-based ceramics

High-performance and low-voltage SnO2-based varistors

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Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors

Structural, nonlinear electrical characteristics, and stability against DC‐accelerated aging stress behavior of Er‐doped 20 nm ZnO–Bi₂O₃–Mn₂O₃‐based varistors