This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
As discussed in Section of Elastic Scattering of Incident Electron with an Atomic Nucleus, the crystalline specimen scatters electrons at discrete angles, named by Bragg angles. The elastic scattering is then called diffraction. However, because of atomic vibration, electrons can also undergo phonon scattering, broadening the angular width of each Bragg beam. The diffraction broadening, indicated by the width of the dark rods in Figure 4758, is due to an energy transfer of the order of kT (≈25 meV at T ≈ 300 K). This scattering, involving interaction with atomic nuclei by phonon is often termed quasi-elastic.
Figure 4758. Curves show the angular distribution of elastic and
inelastic scattering, calculated for 200 keV electrons in amorphous
carbon. Vertical bars represent the relative intensities of the elastic
Bragg beams in crystalline diamond when the crystal axes are
parallel to the incident beam. 
 Egerton, R. F., 2009. Electron energy-loss spectroscopy in the TEM, Rep. Prog. Phys. 72, 016502, 25.