Electron Microscope Investigation of Extinction Line Contours in Copper Oxide Whiskers

Abstract

Oxide whiskers were grown in dry air on pre‐worked and pre‐annealed copper and studied by high‐magnification transmission electron microscopy. Examinations of individual whiskers at high magnifications revealed a complex array of lines of strong contrast within some of the crystals. Stereoscopic examinations of single whiskers revealed that the lines were not associated with any thickness variation within the crystal. The application of diffraction contrast and dark field techniques indicated that the lines in most cases were a result of loss of illumination due to Bragg reflections, perhaps as a result of bending or elastic buckling of the whisker. Only in a few isolated cases, when line contrast reversals were obtained in the dark field images, was it possible to associate these lines with an inherent strain field in the whisker. The extinction bend contours observed in the broader whiskers formed on pre‐worked copper were normally more complex than those exhibited by the thinner whiskers formed on the pre‐annealed specimens.