METHODOLOGY PROTOCOLCrystallography & XRD
Powder XRD Phase Identification & Zero-Shift Corrections
Bragg law diffraction geometry, resolving crystallographic space groups, Scherrer crystallite size calculation, and Rietveld refinement.
Scientific Principles & Procedural Takeaways
1
Scherrer Equation: D = (K * lambda) / (beta * cos(theta)) strictly applies only below ~100-200 nm crystallite sizes.
2
Preferred Orientation: Plate-like or needle-like crystals distort relative peak intensities; use sample spinning or capillary geometry.
⚙ Critical Instrument Parameters
Settings & Acquisition Nuances
Goniometer step size (0.01-0.02 deg 2-theta), dwell time per step (1-3 s), divergence slit angle.
⚠️ Critical Bench Pitfall & Troubleshooting
Common Artifacts & Prevention
Instrumental zero-shift errors shift all peaks, producing false lattice parameter expansion. Correct with internal Si standard.
📥 Starter Practice Datasets
Practice CSV Profile
Download Dataset (pxrd_practice_profile.csv)Example Practice Data: Powder XRD Diffraction Profile (CSV)
Pedagogical starter 2-theta vs intensity diffraction profile for practicing peak fitting and phase indexing.