Electron microscopy and diffraction of synthetic corundum crystals

摘要: Abstract Boules of aluminium oxide containing various impurities, grown by the Verneuil technique, have been examined transmission electron microscopy. Most samples dislocation densities ∼5×105 cm−2, excluding grain boundaries. This is two orders magnitude higher than that for comparable undoped crystals. There a incidence low angle boundaries and characteristics these are described. The rarely contain internal precipitates; furthermore, precipitates in sapphire do not normally create significant numbers dislocations. interactions singularity with basal network dislocations ⅓〈1120〈 Burgers vectors analysed. configuration consistent being 〈1010〉 dislocation, but it can be explained assigning ⅓〈1011〉 vector.