Electron optical study of rutile

Convergent-beam electron diffraction has been used to confirm the accepted space group of rutile (TiO₂) and to study in detail the dependence of the intensity of the space-group-forbidden reflections on crystal thickness and orientation. The observations are shown to be in detailed agreement with computer-simulated patterns calculated using the standard structural parameters. The diffraction results provide a basis for understanding the high-resolution electron-microscope images of rutile crystals oriented close to the [001] zone in which the effects of the space-group-forbidden reflections are important. It is concluded that satisfactory agreement exists between experimental and calculated images provided that allowance is made for uncertainty in the orientation of the crystal.