higher-order Laue zone (HOLZ) reflection

Laue zones are the reciprocal lattice planes perpendicular to the direction of the incident beam. The Laue zone containing the point of origin (reciprocal lattice point corresponding to the incidence point) is called the zeroth-order Laue zone (ZOLZ). The Laue zone of the n-th-order counted from the point of origin in the direction opposite to the incident beam direction is called the n-th-order Laue zone. Laue zones other than ZOLZ are termed "higher-order Laue zones (HOLZ)."
Fig. 1(a) shows a (selected-area) diffraction pattern taken with parallel incident beams. The reflections belonging to a HOLZ appear as ring-shaped diffraction spots at positions distant from the center of the diffraction pattern. Fig. 1(c) is an enlarged pattern of (a). Fig. 1(b) shows a convergent-beam electron diffraction (CBED) pattern taken with a conically-focused (convergent) beam. The HOLZ reflections appear as narrow ring lines at positions distant from the center of the pattern. Fig. 1(d) is an enlarged pattern of (b). The HOLZ reflections are more clearly seen in the CBED pattern than in the selected-area diffraction pattern.
The HOLZ reflections provide three-dimensional information on a crystal, whereas, the ZOLZ reflection gives only two-dimensional information on a crystal. The HOLZ reflections have larger diffraction vectors and their positions are sensitive to a slight change of the lattice parameters. Thus, the HOLZ reflections are effectively used for high-accuracy analysis of lattice distortions and crystal structures.

Fig. 1. Diffraction patterns of a Si [111] single crystal. (a) Selected-area diffraction pattern and (b) Convergent-beam electron diffraction (CBED) pattern. (c) Enlarged pattern of (a). (d) Enlarged pattern of (b). Orange and red arrows in (c, d) indicate the same reflections shown in (c) and (d).
In the CBED pattern, the angular distribution of the reflection intensity is visible.

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