Effect of two-step sintering on rare earth (RE = Y2O3, Pr6O11) doped ZnO–Bi2O3 varistors processed from ‘nano-precursor’ powders

Mahesh, K. V.; Anas, S.; Rahul, S.; Ananthakumar, S.

doi:10.1007/s10854-012-0961-9

Cited by 11 publications

(4 citation statements)

References 30 publications

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“…This procedure, described elsewhere, should lead to fine and dense microstructures. 22,23 IEDP measurements.-The oxygen diffusion coefficient D* and surface exchange coefficient k* were determined by the so-called isotopic exchange depth profile (IEDP) technique combining isotopic exchange of 18 O (used as an oxygen tracer) and determination of the 18 O penetration profiles by TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) analyses. The procedure is described in detail elsewhere.…”

Section: Methodsmentioning

confidence: 99%

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Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties

Guesnet

Bonnet

Heintz

et al. 2023

J. Electrochem. Soc.

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This study describes the successful sintering of Pr6O11, which has recently been developed as a promising oxygen electrode for solid oxide cells (SOCs). Using dense pellets or thin films is mandatory prior to an accurate measurement of the ionic transport properties via the isotopic oxyen exchange method here involved. Dilatometry experiments performed under different atmospheres (argon, air, and oxygen) and sintering tests with different thermal cycles overcame the detrimental phase changes of Pr6O11 and densifies this oxide with a sintered relative density of 95%. Dense pellets of large sizes were prepared. In a second part, the ionic transport properties of Pr6O11 have been determined in the range 400 < T°C < 800 thanks to isotopic exchange depth profiling measurements.

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Section: Methodsmentioning

confidence: 99%

“…This process is based on a first heating step performed at high temperature in order to induce the densification process, followed by a fast cooling, down to an intermediate temperature to continue the densification without grain growth. This procedure, described elsewhere, should lead to fine and dense microstructures [22][23].…”

Section: Sintering Cyclesmentioning

confidence: 99%

Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties

Guesnet

Bonnet

Heintz

et al. 2023

J. Electrochem. Soc.

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“…That is why the activation energy for grain-boundary diffusion is lower than that for grain-boundary migration. Thus, the sintering technique was successful in sintering nano-sized powders with high grain-boundary diffusivity [6][7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Low-temperature sintering behaviors in a titanium oxide–copper oxide system through two-step heat treatment

Woo

Chung

et al. 2020

J. Korean Ceram. Soc.

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The low-temperature sinterability of TiO 2 -CuO systems was examined through a two-step sintering process. The first-step heat treatment was carried out at 900 °C for either 5 min or 1 h. The subsequent second-step sintering by reheating after cooling proceeded at 800 °C for various times. Micron-sized (2 µm) powders as received were used as the starting materials. In the present system, the densification behaviors through grain-boundary diffusion were similar to those in nanocrystalline ceramics at low temperatures. The difference in temperature sensitivity for densification or grain growth was thus exploited to enhance densification and hinder grain growth. As a result, enhanced densification without notable grain growth was achieved after second-step sintering, as opposed to conventional sintering at 800 °C. This implies that the grain-boundary diffusion contributing to densification was more active than the grain-boundary migration at 800 °C. In this regard, the current results show a trait of activated sintering as well.

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“…ZnO varistors are semiconducting ceramics made from ZnO and other metal oxides such as Bi 2 O 3 , Sb 2 O 3 , Co 2 O 3 , Cr 2 O 3 and MnO, etc. Due to their highly nonlinear current-voltage characteristics and energy handling capabilities, ZnO varistors have been widely used as surge absorbers in small current electronic circuits as well as large current transmission lines for overvoltage protection [3,4]. Synthesis of ultrafine powders of high purity and controlled particle shape and size is the primary step in the production of varistors with reliable ceramic and electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of monodisperse ZnO nanostructures via a solvent extraction route and its use in varistor ceramics

Wang

Chen

Zhang

2015

J Mater Sci: Mater Electron

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An approach to synthesize monodisperse ZnO nanostructures through a solvent extraction route has been developed in the present work. The dispersive ZnO nanoneedles with little agglomeration can be synthesized at the equal moles of PC-88A and N1923. The ZnO nanostructures exhibit flower-like morphology with the dimension of 200-250 nm with pointed tip of 80-100 nm size when the molar ratios changed to 3:1. Plausible growth mechanism for the formation of monodisperse nanostructure has been discussed in detail. Additionally, using doped-ZnO powders via this solvent extraction route after sintering in air at 1150°C for 2 h, the varistor possesses good electrical characteristics, with present nonlinear coefficient (26.2 ± 0.63) and high breakdown voltage (285 ± 5 V/ cm), low leakage current (0.18 ± 0.08 lA).

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Effect of two-step sintering on rare earth (RE = Y2O3, Pr6O11) doped ZnO–Bi2O3 varistors processed from ‘nano-precursor’ powders

Cited by 11 publications

References 30 publications

Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties

Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties

Low-temperature sintering behaviors in a titanium oxide–copper oxide system through two-step heat treatment

Synthesis of monodisperse ZnO nanostructures via a solvent extraction route and its use in varistor ceramics

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Effect of two-step sintering on rare earth (RE = Y2O3, Pr6O11) doped ZnO–Bi2O3 varistors processed from ‘nano-precursor’ powders

Cited by 11 publications

References 30 publications

Densification Study of Pr6O11 as a Limiting Step for the Determination of Its Oxygen Transport Properties

Densification Study of Pr6O11 as a Limiting Step for the Determination of Its Oxygen Transport Properties

Low-temperature sintering behaviors in a titanium oxide–copper oxide system through two-step heat treatment

Synthesis of monodisperse ZnO nanostructures via a solvent extraction route and its use in varistor ceramics

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Product

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Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties

Densification Study of Pr₆O₁₁ as a Limiting Step for the Determination of Its Oxygen Transport Properties