Final answer:
The challenges and observations related to using SEM/TEM in identifying APBs in polycrystalline materials are discussed. SEM provides a 3-D view but has lower resolution compared to TEM.
Step-by-step explanation:
The passage discusses the challenges and observations related to the use of electron microscopy techniques (SEM/TEM) in identifying anti-phase domain boundaries (APBs) in polycrystalline materials.
The scanning electron microscope (SEM) provides images by using secondary electrons produced by the primary beam interacting with the surface of the sample, while the transmission electron microscope (TEM) allows one to see internal structures such as organelles and the interior of membranes. The SEM has the advantage of providing a 3-D view, but its resolution is about ten times less than a TEM.