X-Ray Diffraction: Identifying Phases and Crystal Structure
Bragg diffraction, peak position, intensity and broadening explained as a practical phase-analysis toolkit.
Why diffraction works
Periodic atomic planes scatter X-rays. Constructive interference occurs at specific angles described by Bragg’s law, creating a pattern characteristic of the crystal structure.
What peak position means
Peak positions reveal interplanar spacing and lattice parameters. Shifts can indicate composition change, temperature, elastic strain or calibration error.
What intensity means
Relative intensity depends on crystal structure, phase fraction, texture, absorption and instrument geometry. Preferred orientation can strongly distort expected patterns.
What broadening means
Peak width can reflect small coherent domain size, microstrain and instrumental broadening. These effects must be separated before interpretation.
Working rule
Use reference patterns as a starting point, then test whether texture, overlapping peaks and sample preparation could support another explanation.