What is X-ray Powder Diffraction (XRD) X-ray powder diffraction (XRD) is a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. In other methods a single crystal is required whose size is much larger than microscopic dimensions. However, in the powder method as little as 1 mg of the material is sufficient for the study. The analyzed material is finely ground, homogenized, and average bulk composition is determined. 3