Powder X-ray Diffraction (pXRD)

Powder XRD is mainly used for structural analysis of microcrystalline solid materials or powder samples. The main benefits of powder diffraction is that sample preparation is often very easy and straightforward. Typically powder XRD instruments use standard X-ray tubes providing a line focus divergent X-ray beam in Bragg-Brentano geometry. For some applications like microdiffraction and 2D diffraction, a microfocus tube is very beneficial.

Application examples for Powder X-ray Diffraction (pXRD)

High entropy oxide
Real-time XRD

Challenging high entropy oxide samples

Researcher at Karlsruhe Institute of Technology utilized a STOE Stadi MP goniometer powered by a MetalJet D2+ to investigate challenging high entropy oxide (HEO) samples. The challenge was to measure a large number of samples and that for every type of sample only a small amount was available. By illuminating the powder samples with a focused bright and small beam of quasi monochromatic Gallium K β radiation, a good signal to noise ratio was obtained with an acceptable measurement time. Powder XRD data sets of a HEOs with varying composition are illustrated here.

For more details, please see the references:

Wang et.al.: Spinel to Rock-Salt Transformation in High Entropy oxides with Li Incorporation. Electrochem 2020, 1, 60–74;doi:10.3390/electrochem1010007

Wang et.al.: Multi-anionic and –cationic compounds: new high entropy materials for advanced Li-ion batteries. Energy Environ. Sci. 2019; doi: 10.1039/c9ee00368a

Real-time XRD in the lab

At the Helmholtz-Zentrum Berlin (HZB), a MetalJet source is used to investigate chemical and physical reactions during growth or decay of photovoltaic absorber films or in-operando studies of batteries by in-situ 2D-XRD. The setup fills a gap between synchrotron beamlines – with high photon flux, but low availability – and standard XRD – with high availability, but insufficient photon flux. Using weakly focusing optics, the time resolution can reach the sub-second regime – here shown with a measurement of a Cu(In,Ga)Se2 absorber film used for solar cells. The figure at the bottom shows the time evolution of a phase transition in a perovskite thin film.

For more information, please see the references:

M. Wansleben, C. Zech, C. Streeck, J. Weser, C. Genzel, B. Beckhoff and R. Mainz. Photon flux determination of a liquid-metal jet x-ray source by means of photon scattering. J. Anal. At. Spectrom. 34, 1497-1502 (2019), doi: 10.1039/C9JA00127A.

H. Näsström, P. Becker, J. Márquez, O. Shargaieva, R. Mainz, E. Unger and T. Unold. Dependence of Phase Transitions on Halide Ratio in Inorganic CsPb(BrxI1-x)3 Perovskite Thin Films Obtained from High-Throughput Experimentation. J. Mater. Chem. A (2020), doi: 10.1039/D0TA08067E.

Article: Solar cells: Mapping the landscape of Caesium based inorganic halide perovskites