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Reactive flash sintering: MgO and α‐Al 2 O 3 transform and sinter into single‐phase polycrystals of MgAl 2 O 4
Author(s) -
Yoon Bola,
Yadav Devinder,
Ghose Sanjit,
Raj Rishi
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.15974
Subject(s) - cubic zirconia , spinel , sintering , materials science , flash (photography) , phase (matter) , oxide , monoclinic crystal system , mineralogy , bismuth , ceramic , yttria stabilized zirconia , metallurgy , analytical chemistry (journal) , chemical engineering , crystallography , crystal structure , chemistry , optics , physics , organic chemistry , chromatography , engineering
We show that flash experiments with three phase mixed‐powders of yttria‐stabilized zirconia (8YSZ), MgO, and α‐Al 2 O 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.