In this project, we aim to compare different X-ray crystallography techniques, used for proteins, small molecules and mineral macromolecular samples to understand what the main differences in sample preparation and their applications are. We also used a Bruker D6 Phaser X-ray Diffractometer to analyze quartz and halite samples, both in powder and solid form and compared the resulting diffraction spectra. This information may be helpful for Physics students investigating atomic structure or biochemistry students interested in various XRD sampling techniques.

Different crystallographic techniques require different sample preparation methods depending on the material being studied. In small molecule crystallography, highly ordered single crystals are typically grown through methods such as slow evaporation, cooling, or vapor diffusion, allowing for very high-resolution structural data such as precise atomic positions and bond lengths. Protein crystallography involves more complex preparation, requiring protein expression, purification and crystallization methods such as hanging drop vapor diffusion. Because protein crystals contain large amounts of solvent and are less ordered, they typically produce lower resolution data focused on overall protein folding and active site structure.

For mineral and inorganic samples, either single-crystal or powder diffraction may be used. Powder X-ray diffraction requires grinding the sample into a fine powder to produce randomly oriented crystallites, often generating more complete diffraction patterns for phase identification and lattice analysis. In contrast, solid single crystals may only diffract strongly along certain orientations depending on how the crystal is positioned relative to the incident beam. Thus, while single-crystal methods generally provide more detailed 3D structural information, powder diffraction can sometimes produce richer or more representative diffraction patterns for mineral characterization.