waxs

Wide-Angle X-ray Scattering (WAXS) is an X-ray scattering technique used to probe the short-range and crystallographic order of materials by detecting X-rays scattered at relatively large angles. It complements small-angle X-ray scattering (SAXS), which targets larger length scales; together they provide information from nanometer to atomic scales.

Principles and information obtained: When X-rays interact with a material, their scattering pattern reflects the arrangement of electrons in the sample. In crystalline regions, interference from periodic planes produces sharp Bragg peaks whose positions yield lattice parameters and crystal structure. In amorphous regions, broad halos indicate lack of long-range order. Analyzing peak positions, intensities, and widths provides phase identification, lattice parameters, crystallite size, strain, and preferred orientation (texture). The scattering vector q, defined by q = 4π sin θ / λ, relates the measured angle to real-space distances.

Instrumentation and geometry: WAXS can be performed with laboratory X-ray sources (for example copper Kα radiation) or at synchrotron facilities. Measurements are done in transmission or reflection geometry, often with two-dimensional detectors that record rings or arcs. Data are commonly converted to intensity versus 2θ or versus q and may be subjected to refinements such as Rietveld analysis for crystal structures or Fourier-based methods to extract crystallinity.

Applications and scope: WAXS is widely used to characterize polymers, pharmaceuticals, ceramics, minerals, catalysts, and nanomaterials, enabling phase identification, crystallinity assessment, lattice parameter determination, and evaluation of texture. It is frequently employed in combination with SAXS to obtain a comprehensive structural picture across multiple length scales.