Coincidence HRTEM images

First, the (0112) face contains an array of equivalent Cr3+ ions in fivefold (square pyramidal) coordination separated by 0.365 nm (corresponding to 6.8 Cr ions/100 A2). The plane defined by the the four oxygen ions surrounding each Cr3+ ion does not coincide with the surface plane, indicating that not only is the surface slightly rumpled but also the direction, where the electric field associated with positive charge is maximized, is not perpendicular to the surface plane. HRTEM images show that these faces are the predominant ones. 

For bimetallic PdCu particles crystallized on MgO, an ordered structure (type CsCl) is always obtained after annealing. The particles are epitaxially oriented (001) on the substrate, with perfect coincidence between the lattices. The correspondence between experimental and simulated HRTEM images, and numerical analysis, are indicative of a layer of Pd at the interface between the alloy and MgO, with the atomic columns aligned with those of MgO. 

Using HRTEM the chiral angle can also be deduced from the moird or coincidence pattern formed in the central area of the tube image between "front" and "back" surfaces of the tube. 

Figure 20. HRTEM micrograph of an M0S2 wear particle, with atomic resolution. The electron beam was parallel to the c-axis. The calculated diffrac-tograms correspond to the image frames showing Moire patterns. Areas where atomic coincidence has disappeared are characterized by a misfit angle of 30 between two superimposed crystals.

The process of stacking fault folding involves stair-rod dislocations to mediate between the different prismatic and pyramidal crystal planes because the displacement vectors of the stacking faults on the (1100) and (1102 planes are not the same. An HRTEM plan-view image of the tip of a prismatic/pyramidal stacking fault domain found in an HVPE film is shown in Figure 11.16. The arrows indicate the position of stair-rod dislocations. It is noteworthy that the tip involves the interaction of an fr-type BSF, representative for all such domains found in the film. The tip position coincides with a terminated BSF and consists of two PyS F, each of them subsequently folding onto the m plane. 

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