On basal slip and basal twinning in sapphire ({alpha}-Al{sub 2}O{sub 3}). 3: HRTEM of the twin/matrix interface

Journal Article · Wed May 01 04:00:00 EDT 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00288-X· OSTI ID:247967

Geipel, T; Bilde-Soerensen, J B; Lawlor, B F; Pirouz, P; Lagerloef, K P.D.; Heuer, A H ^[1]

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1. Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering

A high resolution transmission electron microscopy (HRTEM) investigation of basal twins in sapphire ({alpha}-Al{sub 2}O{sub 3}) indicates that they are either Type-II or Type-I ``glide`` twins. These two types cannot be distinguished with the resolution of the HRTEM used in the present study. However, a Type-II twin is consistent with the model of basal twinning presented in the second paper of this series, with an AC{prime}BA{prime}CB{prime}/a{prime}bc{prime}ab{prime}c stacking sequence for the Al-O-Al layers along a direction perpendicular to the twin/matrix interface, and pair potential calculations suggest that Type-II interfaces have the lowest energy of all possible twin interfaces in sapphire. An overlap of the twin/matrix leads to Moire-like contrast features. This can also be explained with the proposed twinning mechanism.

• DOE Contract Number: FG02-93ER45496
• OSTI ID: 247967
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COULOMB ENERGY
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
DEFORMATION
ORIENTATION
SAMPLE PREPARATION
SAPPHIRE
SIMULATION
SLIP
TRANSMISSION ELECTRON MICROSCOPY
TWINNING