Comparison of the grain growth behavior and defect structures of flash sintered ZnO with and without controlled current ramp

Phuah, Xin Li; Wang, Han; Charalambous, Harry; Jha, Shikhar Krishn; Tsakalakos, Thomas; Zhang, Xinghang; Wang, Haiyan

doi:10.1016/j.scriptamat.2018.11.009

Cited by 54 publications

(33 citation statements)

References 34 publications

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“…The apparent density of the samples increased with increasing duration of the electric current ramp. Similar results were reported in the literature . However, the apparent densities obtained under all the studied conditions were similar, with the exception of the 1 CRFS 100 sample.…”

Section: Resultssupporting

confidence: 90%

“…The properties of materials are related to their microstructure; therefore, knowledge of the grain growth kinetics associated with different FS parameters is essential. Thus, one challenge of FS is the production of ceramics with homogeneous microstructure . Some authors believe that it may be possible to avoid heterogeneous microstructure in flash‐sintered (FSed) materials by gradually increasing the electric current in FS using a current ramp (CRFS).…”

Section: Introductionmentioning

confidence: 99%

“…The use of CRFS in sintering of 3 mol% yttria‐stabilized zirconia (3YSZ) has resulted in microstructural homogeneity in experiments using a DC electric field (dog‐bone‐shaped samples) and a preliminary study of AC electric field (cylindrical samples) . Other studies have shown that CRFS increased the densification of zinc oxide samples compared with that obtained by FS …”

Section: Introductionmentioning

confidence: 99%

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Microstructural evolution of 3YSZ flash‐sintered with current ramp control

et al. 2020

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The effect of a controlled current ramp during flash sintering (FS) on the densification and microstructural evolution of 3 mol% yttria‐stabilized zirconia was investigated. The samples were flash sintered using a current ramp control with six different current ramp rates and compared with samples sintered by FS without current ramp control. In both cases, maximum electric current densities of 100 and 200 mA mm−2 were used. The microstructure of cylindrical samples was observed, showing grain size heterogeneity between the curved surface and the core for the flash‐sintered (FSed) samples regardless of the maximum current density used. By contrast, the current ramp FSed samples exhibited a homogeneous grain size when the electric current density of 100 mA mm−2 was applied. Thus, controlling a current ramp during FS can be an alternative for avoiding grain size heterogeneity on ceramics sintered by this technique.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Microstructural evolution of 3YSZ flash‐sintered with current ramp control

et al. 2020

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“…The power supply did not require switching to a current control as the current stayed constant and did not increase indefinitely, unlike typical flash sintering of bulk samples. During the flash sintering of bulk ceramics, the current increase is typically correlated with the densification of the sample . Figure C shows a snapshot of the sample glowing when the current began to flow through the thin film.…”

Section: Methodsmentioning

confidence: 99%

“…Since ceramics have a negative temperature coefficient of resistivity, increasing the furnace temperature leads to an increase in the conductivity of the sample. At the onset temperature, there will be sufficient conductivity to allow current flow through the green body and abrupt densification of the green body follows . At this point, the mechanism is still unclear and several hypotheses have been proposed, including Joule heating, Frenkel pair formation, electrochemical reactions, and grain boundary overheating or melting …”

Section: Introductionmentioning

confidence: 99%

Field‐assisted heating of Gd‐doped ceria thin film

Phuah

Misra

et al. 2019

J Am Ceram Soc

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Flash sintering has recently been used to sinter various bulk ceramics under reduced sintering temperatures and sintering time by applying an electric field across the sample. In this work, we have demonstrated field-assisted heating of 10 mol% Gddoped CeO 2 thin films deposited by pulsed laser deposition. Microstructure analysis revealed the elongated grains aligned in the out-of-plane direction which is perpendicular to the direction of electric field. The overall microstructure of the flashheated thin film also contained a matrix of porous and clustered regions, which are distributed throughout the thin film from the anode to cathode electrode regions. The flash-heated thin film showed significantly different conductivity and optical permittivity compared to the as-grown thin films. This demonstration suggests a feasible approach for post-deposition synthesis of thin films using field-assisted heating toward novel morphologies and properties. K E Y W O R D Sconductivity, flash sintering, microstructure, permittivity, thin films

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Flash and Breakdown: Thermal Runaway and Dielectric Breakdown as Competing Mechanisms During Flash Sintering of Barium Titanate

et al. 2023

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Herein, hot‐spot generation in bulk barium titanate samples is investigated during controlled current ramping at various rates using in situ dilatometry. The incubation of the flash event is separated from dielectric breakdown at high current densities, which has previously been attributed to cause flash incubation in barium titanate. The lower boundary of the onset temperature of the flash event in barium titanate is investigated through conventional flash experiments at high electric fields. Despite incubating through thermal runaway, the lower boundary does not coincide with the Debye temperature of barium titanate.

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Comparison of the grain growth behavior and defect structures of flash sintered ZnO with and without controlled current ramp

Cited by 54 publications

References 34 publications

Microstructural evolution of 3YSZ flash‐sintered with current ramp control

Microstructural evolution of 3YSZ flash‐sintered with current ramp control

Field‐assisted heating of Gd‐doped ceria thin film

Flash and Breakdown: Thermal Runaway and Dielectric Breakdown as Competing Mechanisms During Flash Sintering of Barium Titanate

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