Powder diffraction

Powder diffraction identifies crystalline structures by measuring how radiation scatters from a sample containing many randomly oriented crystallites. Its diffraction pattern records characteristic spacings between atomic planes.

Bragg's law: Bragg's law relates the angle and wavelength of diffracted radiation to spacing between crystal planes. It converts peak positions into interplanar spacings.
Powder X-ray diffraction: Powder diffraction performed with X-rays to investigate crystalline materials. It is the most widely used laboratory form of powder diffraction.
X-ray crystallography: The study of atomic and molecular structures using X-ray scattering from crystals. Powder diffraction is one approach within this broader structural method.
Single-crystal X-ray diffraction: A method that determines crystal structure from diffraction measured on a single oriented crystal. It can separate reflections that overlap in powder patterns.
Reciprocal lattice: The reciprocal lattice represents the periodicity of a crystal in wavevector space. Powder peaks occur when reciprocal-lattice points satisfy the diffraction condition.
Neutron diffraction: A diffraction technique that uses neutrons to probe atomic and magnetic structures. Neutrons complement X-rays, especially for locating light atoms and magnetic order.
Crystal lattice: A periodic arrangement of points used to describe the translational order of a crystal. Its repeating geometry sets the possible diffraction spacings.
Small-angle X-ray scattering: A technique that measures X-ray scattering at small angles to characterize nanoscale structures. It probes larger-scale features rather than the atomic lattice spacings targeted here.
Structure factor: A complex quantity describing how atoms in a unit cell combine to scatter a wave. It determines which reflections appear and how intense they are.
Phase identification: The determination of which crystalline phases are present in a material. Characteristic powder patterns let analysts identify phases in mixtures.

Linked from 8 pages