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Title: Reactive flash sintering: MgO and α-Al 2O 3 transform and sinter into single-phase polycrystals of MgAl 2O 4

We show that flash experiments with three phase mixed-powders of yttria-stabilized zirconia (8YSZ), MgO, and α-Al 2O 3 not only produce polycrystals of high density, but also the transformation of magnesia and alumina into single-phase spinel. The presence of zirconia facilitates the onset of the flash. The sintering experiments in the laboratory were extended to live experiments at the National Synchrotron Light Source II at Brookhaven National Laboratory in order to measure the time-dependent evolution of single-phase spinel. The phase transformation occurred in <3 seconds during Stage II. Later, during Stage III the cubic zirconia transformed partly into the monoclinic phase, which reverted back to the cubic phase when the flash was extinguished by turning off the current to the specimen. The results underpin a recent report on the synthesis of single-phase bismuth ferrite from constituent oxides in reactive flash experiments, raising the specter of flash as a method for synthesis as well as sintering of complex oxide ceramics. The role of zirconia in catalyzing the flash in the present study is discussed.
Authors:
ORCiD logo [1] ;  [1] ; ORCiD logo [2] ; ORCiD logo [1]
  1. Univ. of Colorado, Boulder, CO (United States). Materials Science and Engineering Program Dept. of Mechanical Engineering
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
Publication Date:
Report Number(s):
BNL-211449-2019-JAAM
Journal ID: ISSN 0002-7820
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Journal of the American Ceramic Society
Additional Journal Information:
Journal Volume: 102; Journal Issue: 5; Journal ID: ISSN 0002-7820
Publisher:
American Ceramic Society
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1503226
Alternate Identifier(s):
OSTI ID: 1476673

Yoon, Bola, Yadav, Devinder, Ghose, Sanjit, and Raj, Rishi. Reactive flash sintering: MgO and α-Al2O3 transform and sinter into single-phase polycrystals of MgAl2O4. United States: N. p., Web. doi:10.1111/jace.15974.
Yoon, Bola, Yadav, Devinder, Ghose, Sanjit, & Raj, Rishi. Reactive flash sintering: MgO and α-Al2O3 transform and sinter into single-phase polycrystals of MgAl2O4. United States. doi:10.1111/jace.15974.
Yoon, Bola, Yadav, Devinder, Ghose, Sanjit, and Raj, Rishi. 2018. "Reactive flash sintering: MgO and α-Al2O3 transform and sinter into single-phase polycrystals of MgAl2O4". United States. doi:10.1111/jace.15974.
@article{osti_1503226,
title = {Reactive flash sintering: MgO and α-Al2O3 transform and sinter into single-phase polycrystals of MgAl2O4},
author = {Yoon, Bola and Yadav, Devinder and Ghose, Sanjit and Raj, Rishi},
abstractNote = {We show that flash experiments with three phase mixed-powders of yttria-stabilized zirconia (8YSZ), MgO, and α-Al2O3 not only produce polycrystals of high density, but also the transformation of magnesia and alumina into single-phase spinel. The presence of zirconia facilitates the onset of the flash. The sintering experiments in the laboratory were extended to live experiments at the National Synchrotron Light Source II at Brookhaven National Laboratory in order to measure the time-dependent evolution of single-phase spinel. The phase transformation occurred in <3 seconds during Stage II. Later, during Stage III the cubic zirconia transformed partly into the monoclinic phase, which reverted back to the cubic phase when the flash was extinguished by turning off the current to the specimen. The results underpin a recent report on the synthesis of single-phase bismuth ferrite from constituent oxides in reactive flash experiments, raising the specter of flash as a method for synthesis as well as sintering of complex oxide ceramics. The role of zirconia in catalyzing the flash in the present study is discussed.},
doi = {10.1111/jace.15974},
journal = {Journal of the American Ceramic Society},
number = 5,
volume = 102,
place = {United States},
year = {2018},
month = {8}
}

Works referenced in this record:

Particle size effects in flash sintering
journal, September 2012

Flash Sintering of Nanograin Zirconia in <5 s at 850�C
journal, September 2010

Field assisted and flash sintering of alumina and its relationship to conductivity and MgO-doping
journal, December 2011