Advanced X-ray Diffraction Monitors Chemical Reactions as They Occur

MSE Graduate student Ryan Anderson is confirming the calibration of the Discover D8 XRD prior to attaching the in-situ reaction cell.

Traditional x-ray diffraction (XRD) allows for the identification of crystalline materials, providing qualitative and quantitative analysis of phase, crystallite size, and degree of crystallinity.  It is a powerful technique for developing a deeper understanding of materials and the processes that make them, since differences between a reactant and product phase can be quantitatively measured.

The new XRD facility run by Dr. Richard E. Riman’s group in the Department of Materials Science and Engineering, Rutgers University, takes x-ray diffraction methods to a new level.  Research is focused on observing the change in materials from reactant to product phase as it happens.  The laboratory features a Bruker D8 Discover X-ray diffractometer with a horizontal goniometer, 10 cm travel xyz stage, and interchangeable parallel beam or Bragg-Brentano x-ray geometry. Collaboration with Pacific Northwest National Laboratory (PNNL) led to the development of the in-situ reaction cell.  By utilizing a unique diffractometer optics configuration and the novel in-situ reaction cell, reactions can be observed in real-time.  Compared with traditional XRD, in which only the beginning and end state can be observed, the new set-up enables us to capture details of the reaction mechanism and kinetics.  Samples placed in the in-situ cell can be heated and reacted with gases like CO2 while complete diffraction patterns are cyclically collected every few minutes with angular resolution higher than 1/50th of a degree.  Empowered with this information, researchers are able to better understand and subsequently improve both materials synthesis and processing parameters. 

The in-situ reaction cell is being used to study materials systems of interest for grants funded by the Army Research Laboratory (ARL), Office of Naval Research (ONR), and the Ceramic Composite and Optical Materials Center (CCOMC), as well as recent start up, Solidia Technologies.  The kinetics of carbonation reactions leading to green cements has been investigated in-situ.  This information has helped improve green cement processing techniques, bringing this important technology closer to mainstream adoption. 

MSE researchers will continue to implement new ways of utilizing the Bruker D8 Discover diffractometer in their research.  Planned additions to the diffractometer set-up will allow reactions at more extreme conditions to be observed.  X-ray transparent hydrothermal vessels with laser heating are being acquired, allowing for better control of reaction parameters while expanding the scope of possible chemistry for the discovery of new materials and their associated processes.