X-Ray Diffraction (Allentown Lab)

X-ray diffraction (XRD), which provides structural information about crystalline phases, occurs when an incident beam of monochromatic X-rays is scattered by the ordered structure of a crystalline phase. This scattering produces a pattern that is characteristic of the arrangement and identity of the atoms in the structure.

Our specialized team of senior scientists, chemists and analysts in Allentown can use XRD to determine the composition of your sample or confirm that a specific compound is found, whether it is present as a powder, film, flat specimen, or dispersed particle in a liquid matrix. In many instances, an unknown residue or precipitate can be characterized in part using XRD with complementary information from an elemental analytical technique (such as X-ray fluorescence).

For example, corrosion on the surface of a steel pipe may be due to exposure to corrosive agents in a process stream or environment. While an elemental analysis would identify Fe as the major element present in the corrosion residue, it cannot distinguish between Fe containing compounds such as Fe₂O₃, Fe₃O₄, FeOOH, FeCO₃, etc. that could suggest a source of corrosion. XRD can easily distinguish between these compounds as well as between polymorphs of these compounds such as the three different crystalline forms of FeOOH that could occur depending on exposure conditions.

Our skilled Allentown staff can also use XRD to:

• Distinguish between polymorphs of the same compound: Polymorphs have the same chemical composition, but different arrangements of atoms that can result in significantly different properties such as the rutile and anatase forms of TiO₂, which have different optical properties when used as pigments or coatings. The ability of XRD to distinguish between polymorphs of compounds finds particular use in stability studies of pharmaceuticals.
• Estimate the concentrations of crystalline compounds in a sample: The crystal structures of identified compounds in a sample can be used in a model that captures all aspects of the XRD analysis to simulate a diffraction pattern than can then be compared to the observed XRD data.
• Examine how a sample changes during heating by doing temperature controlled XRD experiments: Thermal events that are observed via thermal analysis can be probed by performing XRD analysis at a lower temperature than the onset of the event and after holding at the temperature at which the event occurs.

With Intertek as your Total Quality Assurance partner, we can meet all your XRD analysis needs.