Title :
Measurement and correlation of optical and TEM twins in Y1 Ba2Cu3O7-δ
Author :
Chumbley, L.S. ; Verhoeven, J.D. ; Kim, M.R. ; Cornelius, A.L. ; Kramer, M.J.
Author_Institution :
Iowa State Univ., Ames, IA, USA
fDate :
3/1/1989 12:00:00 AM
Abstract :
The spacing of the twins present in Y1Ba2Cu 3O7-δ has been investigated using optical and transmission electron microscopy (TEM). Studies have reported that the value of the average twin spacing obtained by optical measurements is much larger than that measured in thin foils prepared for TEM observation, and controversy exists as to the exact nature of the optical twins. Experiments have been conducted which show that the twins observed optically correspond to those seen using TEM and are not produced by an optical interference effect. Using electron channeling, equations have been formulated which allow optical determination of the true spacing of twins present in a selected grain as well as the orientation of that grain. The average twin spacing measured by TEM has been found to vary with the sample preparation method, being smaller for crushed chip samples than for bulk samples prepared by ion milling or jet-polishing. A variation of the twin spacing with grain size has also been noted
Keywords :
barium compounds; channelling; electron beam effects; grain size; high-temperature superconductors; optical properties of substances; transmission electron microscope examination of materials; twinning; yttrium compounds; TEM twins; Y1Ba2Cu3O7-δ; average twin spacing; electron channeling; grain orientation; grain size; high temperature superconductor; optical measurements; optical twins; thin foils; transmission electron microscopy; Electron optics; High temperature superconductors; Interference; Milling; Optical microscopy; Particle beam optics; Powders; Scanning electron microscopy; Superconducting transition temperature; Transmission electron microscopy;
Journal_Title :
Magnetics, IEEE Transactions on
