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Effect of Residual Strain on the Electronic Structure of Alumina and Magnesia
Author(s) -
Song Huesup,
French Roger H.,
Coble Robert L.
Publication year - 1989
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/j.1151-2916.1989.tb06257.x
Subject(s) - materials science , crystallite , residual stress , band gap , polishing , thermal expansion , analytical chemistry (journal) , spectral line , exciton , anisotropy , condensed matter physics , composite material , optics , chemistry , metallurgy , optoelectronics , physics , chromatography , astronomy
The reflectance spectra of polycrystalline Al 2 O 3 and singlecrystal MgO, with different surface treatments were measured using vacuum ultraviolet (VUV) spectroscopy to determine the effect of residual stresses and strains. The bulk stresses were estimated using the R‐line flourescence of trace Cr 3+ in Al 2 O 3 . No grain‐size dependence was observed for the residual thermal expansion anisotropy stresses in polycrystalline Al 2 O 3 . The effects of mechanical‐polishing‐induced damage in Al 2 O 3 shifted the band‐to‐band and exciton transitions to higher energies, compared with those of chemically polished Al 2 O 3 . There was little difference in peak positions between cleaved and chemically polished surfaces of MgO. However, mechanically polished MgO surfaces exhibited band‐to‐band and exciton‐peak shifts to higher energies. The VUV technique of determining the exciton‐peak and band‐gap shifts was used with knowledge of the band‐gap strain coefficient to estimate the magnitudes of residual surface stresses in the 1‐μm surface layer probed. The polishing‐damage‐induced residual surface stress is 2.2 GPa for Al 2 O 3 and 1.1 GPa for MgO. These values are based on band‐gap strain coefficients of 700 meV/(lin% strain) derived for Al 2 O 3 and 400 meV/(lin% strain) estimated for MgO.