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Electron spin resonance of transparent alumina ceramics fabricated by spark plasma sintering
Author(s) -
Kai Ayako,
Matsuo Kouichi
Publication year - 2018
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.15702
Subject(s) - spark plasma sintering , materials science , ceramic , electron paramagnetic resonance , sintering , laser linewidth , transparent ceramics , analytical chemistry (journal) , nuclear magnetic resonance , absorbance , isotropy , intensity (physics) , composite material , optics , laser , chemistry , physics , chromatography
Transparent α‐alumina ceramics are fabricated using spark plasma sintering. Paramagnetic defects related to the optical properties of the ceramics have been investigated using electron spin resonance ( ESR ) analyses. An isotropic ESR signal at g = 2.003 ( S = 1/2) with a linewidth of 0.5 mT is formed during sintering. The g = 2.003 signal intensity has a weak correlation with the absorbance in the visible region but does not correlate with the real in‐line transmission ( RIT ) at 650 nm. An ESR signal with a fine structure attributed to Fe 3+ was detected in both the α‐Al 2 O 3 starting powder and the sintered ceramic samples. The degree of c ‐axis orientation of the grains has been determined using the Fe 3+ signal intensity, which depends on the angle between the directions of the c ‐axis and the applied magnetic field. The ESR analysis indicated that the c ‐axis tends to be oriented in the direction of the sintering pressure. The degree of c ‐axis orientation was found to correlate with the RIT in highly densified ceramics.