ELDICO’s unique and worldwide first dedicated electron diffractometer delivers proof-of-concept on real samples by solving its first structure ab-initio.
After merely one year of realisation and subsequent calibration in early May, the ELDICO team successfully performed initial measurements on real samples last week.
The ELDICO diffractometer is set up to run with a beam energy of 160 keV. An inorganic substance with known structure (sodium calcium aluminum fluoride, Na2Ca3Al2F14) was used as a reference for a preliminary assessment of the instrument’s performance. This also allowed us to (i) test the workflow in practice, in view of maximised automation of the process and (ii) verify the calibration of instrumental parameters that are necessary for the analysis of unknown crystals.
A series of 600 diffraction patterns was collected spanning a rotation angular range of 120°, with an exposure time of 0.1 second per frame.
The data processing via state-of-the-art crystallographic software1 allowed to reconstruct the 3D diffraction pattern. The pattern could be indexed with a cubic unit cell and space group I213. The observed lattice parameter deviates by only 0.36% with respect to the value of 10.257(1) Å reported in literature2 for the same material characterised with X-ray diffraction, indicating good accuracy on the geometrical parameters.
What is more, the integrated diffraction intensities extracted from the dataset have also allowed to obtain a satisfactory ab-initio solution of the crystal structure by commonly employed charge-flipping methods.3
The measurements confirm that we have built a high-performance electron diffractometer, which can be delivered to customers. Please contact us for a test measurement on your own sample.
References:
[1] Palatinus, L., Brazda, P., Jelinek, M., Hrda, J., Steciuk, G. & Klementova, M. (2019). Acta Cryst. B75, 512-522.
[2] Courbion, G., Ferey, G.; Journal of Solid State Chemistry, 1988, 76, 426-431.
[3] Palatinus L., Chapuis G. (2007): Superflip - a computer program for the solution of crystal structures by charge flipping in arbitrary dimensions. J. Appl. Cryst. 40, 786-79.
ELDICO is grateful to Nicola Casati from PSI for providing the Na2Ca3Al2F14 sample.
