The diffraction contrast from isolated {101} and {1¯32} planar faults in rutile was re-examined from the viewpoint that the displacement vectors R = <uvw> might not be defined by simple integers. The present analysis confirmed the previously reported R = ½<10¯1> at {101} faults, but showed that, at {1¯32} faults, R = ½<0, 0.90, 0.90> and not 1/6<211> as had been suggested. This new value was close to R = ½<011>, which was also the 'ideal' displacement vector at ordered {1¯21} crystallographic shear planes in the reduced rutiles, TinO2n-1 (n = 4 to 9). The modified criterion for extinction, g•R = N±0.02, applied only when the crystal thickness was an integral multiple of the extinction distance. For half-integral values, strong fringe contrast could occur for |g•R - N| < 0.02.

The Displacement Vectors of {1¯32} and {101} Faults in Rutile. Bursill, L.A., Hyde, B.G.: Proceedings of the Royal Society A, 1970, 320[1541], 147-60