Measuring very large data sets of X-ray diffuse scattering allowed researchers to identify how different forms of local order in ferroelectrics correlate with their properties.
What did the Scientists Discover?
Ferroelectric (FE) materials exhibit spontaneous electric polarization that can be reversed by external electric fields. Relaxor ferroelectrics, such as PbMg1/3Nb2/3O3-xPbTiO3(PMN-xPT), are FE materials that exhibit high electrostriction, i.e. they change their dimensions upon application of electric fields. Measuring very large data sets of X-ray and neutron diffuse scattering over a broad range of sample compositions, allowed researchers to identified how different forms of local order in PMN-xPT correlate with its dielectric and electromechanical properties.
Broader Impacts of this work?
The observation and analysis provides new models to relate atomic scale displacements with macroscopic ferroelectric and piezoelectric materials properties. This new understanding opens up yet unexplored pathways for engineering novel environmentally-friendly, i.e. lead free, piezoelectrics to be used for example for energy harvesting.
Why is this important?
Controlling and relating local order to macroscopic properties is key to materials engineering. By measuring large, three-dimensional volumes of X-ray diffuse scattering efficiently, we can now identify how different forms of local order correlate with dielectric and electromechanical properties as well as ordered polarized states.
Why did this research need CHESS?
This research required high dynamic range reciprocal space mapping, i.e. the capability to collect expansive diffraction data sets at high photon energies (56.7keV) with large area photon counting detectors (DectrisPilatus 6 M) available at CHESS undulator beamline A2. The samples were continuously rotated in the beam at 1° per second over 370°, with images read out every 0.1 s. The resulting images were stacked into a three-dimensional array, oriented using an automated peak search algorithm, and transformed in reciprocal space coordinates using the software package CCTW (Crystal Coordinate Transformation Workflow).
How was the work funded?
Work was supported by the US Department of Energy, Office of Science, Materials Sciences and Engineering Division as well as Office of Basic Energy Sciences, Scientific User Facilities Division;
US Office of Naval Research; Natural Sciences and Engineering Research Council of Canada. CHESS was supported by the NSF and NIH/NIGMS via NSF award DMR-1332208.
M. J. Krogstad et al. (ANL, NIST, ORNL, CHESS, Simon Fraser University,
University of Chicago, Northern Illinois University, Shanghai Institute of Ceramics)