microdiffraction

Microdiffraction refers to a family of diffraction techniques designed to obtain crystallographic information from extremely small volumes of material, typically at micron to sub-micron scales. Unlike conventional powder or single-crystal diffraction, microdiffraction interrogates a localized region, often by focusing the incident beam to a small spot or by using a small diffraction aperture. This enables spatially resolved measurements of structure, composition, and strain within heterogeneous materials.

Common implementations include micro-focused X-ray diffraction (μXRD), which uses a focused X-ray beam from a synchrotron or laboratory source to map lattice parameters, crystal orientation, phases, and residual strain over a sample. Electron diffraction techniques in transmission electron microscopy, such as selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and nano-beam electron diffraction, provide local diffraction information from tiny volumes. Scanning electron microscope–based methods like electron backscatter diffraction (EBSD) are closely related, yielding orientation maps over scanned regions.

Data from microdiffraction can yield local lattice parameters, orientation matrices, phase maps, and strain fields, enabling investigations of grain structure, texture, phase transformations, and defects at high spatial resolution. Analysis often involves indexing diffraction patterns, reconstructing reciprocal space, and correlating with imaging data to produce maps of orientation, phase, or strain, sometimes complemented by modeling or simulations.

Applications span materials science, metallurgy, geology, chemistry, and semiconductor research. Microdiffraction is used to characterize polycrystalline materials, study phase distributions in alloys, map crystallographic texture in thin films, and investigate strain evolution during mechanical or thermal treatment. Limitations include radiation damage for sensitive materials, the need for advanced instrumentation, thickness effects in electron-based methods, and the complexity of data interpretation.