10. Glossary

Amorphous

A material that lacks long-range order but has only local atomic organization, resulting in a broad, diffuse diffraction pattern.

Crystal

A material exhibiting a largely discrete diffraction pattern (corresponding to Bragg peaks), according to the International Union of Crystallography (1992). An older definition describes a crystal as the result of the repetition of an atomic pattern; however, there are aperiodic crystals that lack translational symmetry yet exhibit long-range order (and thus a clear and interpretable diffraction pattern).

Diffraction; diffraction

Constructive interference of elastically scattered waves, all of which have the same wavelength. The resulting interference pattern depends on the atomic structure of the material (the position...