AbstractScanning transmission electron microscopy (STEM) is widely used for imaging, diffraction, and spectroscopy of materials down to atomic resolution. Recent advances in detector technology and computational methods have enabled many experiments that record a full image of the STEM probe for many probe positions, either in diffraction space or real space. In this paper, we review the use of these four-dimensional STEM experiments for virtual diffraction imaging, phase, orientation and strain mapping, measurements of medium-range order, thickness and tilt of samples, and phase contrast imaging methods, including differential phase contrast, ptychography, and others.
The lateral growth habits and non-planar conformations of polyethylene
crystals grown from dilute solutions (<0.1% wt./vol.) are known to vary
depending on the crystallization temperature.1-3 With
the notable exception of a study by Keith2, most
previous studies have been limited to crystals grown at <95°C. The trend
in the change of the lateral growth habit of the crystals with increasing
crystallization temperature (other factors remaining equal, i.e. polymer
mol. wt. and concentration, solvent) is illustrated in Fig.l.
The lateral growth faces in the lozenge shaped type of crystal (Fig.la)
which is formed at lower temperatures are {110}. Crystals formed at higher
temperatures exhibit 'truncated' profiles (Figs. lb,c) and are bound
laterally by (110) and (200} growth faces. In addition, the shape of the
latter crystals is all the more truncated (Fig.lc), and hence all the more
elongated parallel to the b-axis, the higher the crystallization
temperature.
Four-Dimensional Scanning Transmission Electron Microscopy (4D-STEM): From Scanning Nanodiffraction to Ptychography and Beyond