J. Phys. Colloques
Volume 49, Numéro C6, Novembre 198835th International Field Emission Symposium / 35éme Symposium International d'Emission de Champ
|Page(s)||C6-489 - C6-493|
J. Phys. Colloques 49 (1988) C6-489-C6-493
ON THE INTERPRETATION OF FIELD ION MICROSCOPY (FIM) IMAGES OF ASYMMETRICAL SPECIMENS OF "1,2,3"-TYPE HIGH-Tc SUPERCONDUCTORSH.B. ELSWIJK, A.J. MELMED et H.A. FOWLER
National Bureau of Standards, Gaithersburg, MD 20899, U.S.A.
Field Ion Microscopy (FIM) specimens of "1,2,3"-type high-Tc superconducting materials, typically have an asymmetrical shape. This results from the anisotropic properties, which are involved in the preparation techniques. As a consequence of this shape, the magnification and resolution depend on the direction in the FIM image. Assuming that the elliptical poles in published micrographs are due to tip shape, we calculate an asymmetry in the magnification as large as a factor of four. Therefore, the current image interpretation is revisited quantitatively, keeping in mind the magnification asymmetry. This strong effect enhances the striped appearance of the images, and has not been fully recognized so far.