PHYS 174-Final Project - Macromolecule Mineral X-ray

Our results: Powder VS. Solid

Quartz

Quartz Solid

Quartz forms hexagonal, elongated prism crystals. In this form, the crystal lattice is continuous and maintains a fixed orientation throughout the sample.

Quartz Powder

In powdered form, quartz consists of many small crystalline grains. Each grain retains the same internal structure, but their orientations vary randomly, meaning the material no longer has a single, uniform lattice direction.

The diffraction spectrum for powder and solid quartz, shown in black and red respectively.

The powdered form of quartz provided a lot more structural detail, as indicated by the presence of more intensity peaks in the diffraction spectrum. Each peak corresponds to a specific set of atomic planes within the crystal, meaning that a greater number of peaks reflects a larger number of interplanar spacings being sampled. This provides more constraints on the crystal structure and allows for a more detailed characterization of the material. In the powdered sample, the presence of many randomly oriented crystallites enables a wider range of lattice planes to satisfy the diffraction condition, resulting in a richer spectrum. In contrast, the single crystal, with its fixed orientation, only satisfies these conditions for a limited set of planes, producing fewer observable peaks. Additionally, the powdered sample showed closer alignment of the intensity peak positions with the overlayed theoretical structure.

The diffraction spectrum for powder and solid quartz, shown in black and blue respectively. The theoretical strcuture of quartz that best matched the experimental data is shown in red.

Halite

Halite Solid

Halite forms perfectly cubic crystals, due to its highly symmetrical internal structure. As a solid crystal, its atomic arrangement is uniform and extends in a single orientation across the sample.

Halite Powder

When halite is ground into a powder, it becomes a collection of many crystals. Again, while each grain preserves the same cubic structure, their orientations are randomly distributed rather than aligned.

The diffraction spectrum for powder and solid halite, shown in black and red respectively.

For halite, there is closer alignment between the powder and solid sample intensity peak locations. The powdered sample displayed peaks closer to the theoretical peaks, but of much lower intensity. This closer agreement in peak positions indicates that both the powder and solid samples probe the same underlying lattice spacings, as expected for a material with a well-defined crystal structure. The lower intensity observed in the powder sample can be attributed to the random orientation of crystallites, which distributes the diffracted intensity over a broader range of angles.

In contrast, the single crystal, with its fixed orientation, allows certain lattice planes to satisfy the diffraction condition more coherently, resulting in stronger and more localized peaks. This is consistent with the high symmetry of halite’s cubic lattice, which supports well-defined and reproducible diffraction features.

Interestingly, the relative peak intensities differed between the two materials. For quartz, the powder sample exhibited stronger peaks, whereas for halite, the single crystal produced higher intensity peaks.

This suggests that crystal symmetry and orientation may play a role in the observed diffraction patterns. Halite’s cubic structure likely allows many equivalent lattice planes to contribute coherently when the crystal is well aligned, resulting in strong single-crystal peaks. In contrast, quartz’s different symmetry may make its diffraction more sensitive to orientation, such that the powder sample, containing many randomly oriented grains, produces stronger overall intensity.

Note: This intensity count depiction of XRD data is not the only way to get Xray diffraction information. Typically, you can retrieve higher dimension diffraction images.

For powders, Debye-Scherrer rings are common outputs as every powder contains grains of all possible orientations of the crystal, which form a cone from a bean. When the cone hits the detector film, it creates continuous circles.

For a single crystal, Laue diffraction are outputs produced by a broad spectrum X-ray beam that, when hitting the crystal, reflects to discrete spots. Each spot represents a set of atomic planes that cohere to an internal symmetery.

These images were coded to map each intensity along a radius 0 to 1, creating rings of appropriate size. A similar process is done for the laue spots, except the choice of 8 versus 6 spots is due to the inherent symmetry of a Quartz and Halite Crystal. Artificial Intelligence was used to both appear like Xray scans and for the laue diffraction pattern. This is meant only to be an example of what data may look like, not as an official source on diffraction patterns generated by these crystals.

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