- "X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions."
Study of the crystal structure and composition of rocks and minerals using X-rays.
Crystallography: The study of the internal structure of crystals, their symmetry and properties.
X-ray sources: Different types of X-ray sources and their properties (electron cyclotron resonance, synchrotrons, rotating anode X-ray tubes).
X-ray Detectors: Different types of X-ray detectors such as scintillation detectors, gas detectors, etc.
Bragg's Law and Diffraction: A mathematical expression that relates the diffraction of X-rays by a crystal lattice to the wavelength of the X-rays and the spacing between the lattice planes.
Crystallographic Planes and Miller Indices: The relationships between planes in crystals, and how Miller indices are used to describe these relationships.
Crystal Structures: Different types of crystal structures such as cubic, hexagonal, triclinic, etc.
Crystal Symmetry: Different types of crystal symmetry, and how it affects the diffraction patterns produced by the crystal.
X-ray Diffraction Pattern: The basic principles involved in creating a diffraction pattern and the importance of the intensity and angles of diffraction spots.
X-ray Powder Diffraction: The technique of collecting diffractograms with X-ray powder diffraction and its application in mineral identification.
X-ray Single Crystal Diffraction and Interpretation of Results: Application of XRD in single-crystal diffraction to decipher the crystal structure of a mineral.
Qualitative and Quantitative Analysis of Minerals: How the diffractograms from powder and single crystal diffraction can be used to identify and quantify minerals in a rock.
Factors Affecting XRD Results: Potential issues in XRD related to specimen preparation, instrumental setup, and data analysis.
Data Analysis and Modeling: Procedures for processing and interpreting XRD data, as well as the use of software for modeling and analyzing complex diffraction patterns.
Powder X-ray Diffraction (PXRD): It is a widely used technique in petrology to determine the mineralogical composition of a rock or mineral. In this method, the X-ray beam is directed onto a powdered sample, and the diffraction pattern is collected. The resulting pattern is analyzed to identify the various mineral phases present in the sample.
Single-Crystal X-ray Diffraction (SXRD): This technique is useful to study the crystal structures of minerals. In this method, a single crystal is mounted on a crystal holder and exposed to X-rays. The X-rays interact with the crystal lattice and produce a diffraction pattern that can be analyzed to determine the crystal structure.
Transmission Electron Microscopy (TEM): It is another technique that is useful in petrology to study the crystal structures of minerals. This method involves the use of a high-resolution electron microscope that can view the atomic scale structure of materials. TEM can provide information about crystal structures, defects, and composition of minerals that cannot be obtained through X-ray diffraction.
Small-Angle X-ray Scattering (SAXS): This technique is used to determine the size and shape of small particles in a sample. In this method, a directional beam of X-rays is passed through a sample, and the scattered X-rays are collected and analyzed.
Wide-Angle X-ray Scattering (WAXS): This method is used to determine the internal structure of minerals, such as their crystal orientation, grain size, and crystallinity. It works similar to PXRD, but the crystal structure of the mineral is obtained by analyzing the scattering pattern in the wide-angle region.
Time-Resolved X-ray Diffraction (TR-XRD): It is a specialized technique that is used to study the structural changes that occur in minerals over time, such as phase transitions or chemical reactions. In this method, the sample is exposed to an X-ray beam, and diffraction patterns are collected at various time intervals. The resulting data can be analyzed to determine the kinetics of the structural changes.
Grazing-Incidence X-ray Diffraction (GIXRD): This method is useful for studying surfaces and interfaces of minerals. In this technique, a small angle of incidence is used, and the X-rays interact with the surface layer of the mineral, producing a diffraction pattern that is analyzed to determine the crystallographic structure of the interface.
- "By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal."
- "From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information."
- "Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields."
- "In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various materials, especially minerals and alloys."
- "The method also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins, and nucleic acids such as DNA."
- "X-ray crystallography is still the primary method for characterizing the atomic structure of new materials and in discerning materials that appear similar by other experiments."
- "X-ray crystal structures can also account for unusual electronic or elastic properties of a material, shed light on chemical interactions and processes, or serve as the basis for designing pharmaceuticals against diseases."
- "X-ray crystallography is related to several other methods for determining atomic structures. Similar diffraction patterns can be produced by scattering electrons or neutrons, and neutron scattering can be similarly interpreted by Fourier transformation."
- "If single crystals of sufficient size cannot be obtained, various other X-ray methods can be applied to obtain less detailed information; such methods include fiber diffraction, powder diffraction, and (if the sample is not crystallized) small-angle X-ray scattering (SAXS)."
- "If the material under investigation is only available in the form of nanocrystalline powders or suffers from poor crystallinity, the methods of electron diffraction, transmission electron microscopy, and electron crystallography can be applied for determining the atomic structure."