Specular X-ray Diffraction (θ-2θ scan)
Specular X-ray diffraction is a powerful analytical technique utilized to investigate the crystallographic properties of thin films and surfaces with exceptional precision. This method capitalizes on X-ray diffraction, where incident X-rays interact with the periodic atomic structure of a sample, resulting in the scattering of X-rays in specific directions.
The mechanism of specular X-ray diffraction involves directing a monochromatic X-ray beam onto the sample surface at a precise angle, known as the glacing incidence angle. As X-rays interact with the crystal lattice of the sample, they undergo constructive interference, generating distinct diffraction peaks at specific angles. This phenomenon allows researchers to analyze the intensity and position of these diffraction peaks, providing valuable insights into various crystallographic parameters, such as crystal orientation, lattice spacing, and crystal quality. Specular X-ray diffraction plays a crucial role in materials science, semiconductor research, and thin film technology, facilitating the characterization and optimization of materials for a wide range of industrial and technological applications.
Chemistry
This study explored how coal's chemical and structural features affect coalbed methane behavior, examining adsorption, desorption, and diffusion. Using XRD analysis, crystallite properties were assessed across different coal ranks, depicted in Figure 1. The XRD spectra showed distinct peaks at (002) and (100), indicating the stacking structure of aromatic layers. The intensity of the (002) peak increased with maturity, and the (100) peak exhibited a slight rise in high-rank samples. Peaks shifted towards larger angles with higher carbon content. The calculated crystallite structural parameters, revealed trends during coalification (Table 1), with increasing average crystallite diameter (La) values, except for XJ-1, suggesting lower-rank coals with a less-ordered structure. Average crystallite height (Lc) values generally increased initially and then decreased in the SX-3 sample at a specific coalification stage (%Ro=2.07%).
Reference:
Shike Li, Yanming Zhu, Yang Wang, and Jing Liu. The Chemical and Alignment Structural Properties of Coal: Insights from Raman, Solid-State13C NMR, XRD, and HRTEM Techniques. ACS Omega, 2021, 6, 11266−11279.
https : //pubs.acs.org/doi/epdf/10.1021/acsomega.1c00111
Nano Materials
In this study, the obtained NanoFlakes (NFLs) in samples A and B exhibited distinctive characteristics, with lateral sizes of approximately 3–5 nm and 30 nm, respectively. Both demonstrated irregular and ultrathin layered structures. Analysis of the experimental XRD data in Figure 2a revealed multiple peaks due to characteristic broadening in nano-scale structures. The samples exhibited a mixed nature, with representation by 1T' and 2H phases, as indicated by the reference bars in Figure 2b,c . This distinction was further supported by Debye function calculations. Differences in NFLs thickness between samples A and B primarily contributed to the variations in XRD patterns. The integration of XRD and XPS analysis in this study facilitated the discrimination of NFLs crystal habit and an estimation of the exact number of atomic monolayers in the 2D -WS2 nanocrystalline samples.
Reference:
Scarfiello R., Mazzotta E., Altamura D., Nobile C., Mastria R., Rella S., Giannini C., Cozzoli PD, Rizzo A., Malitesta C. An Insight into Chemistry and Structure of Colloidal 2D- WS2 Nanoflakes: Combined XPS and XRD Study. Nanomaterials 2021, 11, 1969.
https://doi.org/10.3390/nano11081969
Pharmaceutics
In this research, X-ray Diffraction (XRD) was employed to determine the crystalline phase purity of two novel pharmaceutical cocrystals involving dihydroflavonol and BPY (2C15H12O7•3(C10H8N2), DHQ•BPY); and (C15H12O8•2.5(C10H8N2 ), DMY•BPY). The results show a close correspondence of the crystalline phase peaks with the characteristic peaks and patterns of active pharmaceutical ingredients (APIs) and conformers (CCF) (Fig. 4a and 4b), distinct from those of APIs and CCF. The physical mixtures and cocrystal samples exhibit noticeable differences, confirming the formation of the respective molecular compounds DHQ•BPY and DMY•BPY.
Reference:
Lixin Liu, Moqi Liu, Yunan Zhang, Hemei Yin, Xin Su, Qiang Zhang, Yanru Feng, Yingxue Guo, Dongyu Zou, Yingli Liu. The role of 3-OH in the self-assembly of pharmaceutical cocrystals of dihydroflavonol with 4,4′-bipyridine. New J. Chem., 2021, 45, 1626.
https://pubs.rsc.org/en/content/articlelanding/2021/nj/d0nj04113k