Effect of crystal and beam tilt on simulated high-resolution TEM images of interfaces

It is well known that only a few milliradians of crystal or beam tilt can produce image artifacts in HRTEM images of perfect crystals. One important application of HRTEM is for determining the atomic structures of interfaces. While it is intuitive that alignment of an interface parallel to the electron beam should be critical for obtaining reliable HRTEM images of interfaces, a systematic study of the effects of crystal and beam tilt on HRTEM images of interfaces has not been performed.In this investigation, the effects of crystal and beam tilt on HRTEM images of planar, coherent interfaces were determined by multislice image simulations. Interfaces in metallic systems ranging from simple twin boundaries in f.c.c. Al and b.c.c. Ti to relatively complex interphase boundaries between ordered h.c.p. and b.c.c. phases in the Ti-Al system were examined and compared. Although this study was limited to coherent interfaces, similar effects are expected to occur in comparable nonmetallic systems such as semiconductors and ceramics and for less coherent interfaces as well.