What is X-ray diffraction used for in materials science?

• A. Identify crystal structure and phases, determine lattice parameters, and assess crystallographic texture.
• B. Measure electrical conductivity and magnetic permeability.
• C. Determine porosity and grain size via imaging.
• D. Assess thermal expansion coefficients only.

Answer: (A)

X-ray diffraction reveals how atoms are arranged in a material by how X-rays interfere after scattering from crystal planes. The resulting pattern has peaks at angles that correspond to specific interplanar spacings. By applying Bragg’s law, you link those peak positions to the crystal structure and identify which phases are present, since each phase has a characteristic set of d-spacings. The lattice parameters, describing the size and shape of the unit cell, come from the peak positions and can be refined to give precise values. The way the peaks are distributed in intensity also tells you about texture, or preferred grain orientation, which can influence properties like strength and anisotropy. In short, X-ray diffraction is a go-to method for identifying crystal structure and phases, determining lattice parameters, and assessing crystallographic texture. Other properties—such as electrical conductivity, magnetic permeability, porosity or grain size from imaging, and pure thermal expansion measurements—are obtained with different techniques, so XRD focuses on the atomic arrangement and its consequences for structure.