Characterization of Particle Orientations in Ceramics by Electron Paramagnetic Resonance

Abstract

It is shown that electron paramagnetic resonance spectroscopy provides an accurate method for measuring the preferential orientation of axial crystallites in ceramics. Since the physical properties of ceramic materials are correlated with the degree of this orientation, EPR can be a convenient and useful tool for the characterization of ceramics.

Electron spin resonance of transparent alumina ceramics fabricated by spark plasma sintering

“…Line A originates from the transitions between the fourth and fifth energy levels in the d‐electron energy levels of Fe 3+ . The intensity of line A was reported to be at a maximum when the c ‐axis of α‐Al 2 O 3 doped with Fe 3+ was parallel to the applied magnetic field . Therefore, this finding allows for the orientations of the grains in α‐Al 2 O 3 ceramics to be characterized.…”

“…Aside from the g = 2.003 signal, several ESR lines were observed for all of the samples, as shown in Figure . These ESR lines are attributed to a fine structure of Fe 3+ ions substituted into Al sites in the α‐Al 2 O 3 crystals . The Fe 3+ signal was also detected in the starting powder, which contained approximately 6 ppm of iron as an impurity, and its intensity increased as the sintering temperature increased.…”