Resonant X-ray Diffraction under optimized destructive interference for highly sensitive determination of phase-resolved site-selective atomic displacements in crystalline materials
Mineralogy, Petrology and Geochemistry
Final Report Abstract
The project "Resonant X-ray Diffraction under optimized destructive interference for highly sensitive determination of phase-resolved site-selective atomic displacements in crystalline materials" (REXSuppress) is based on the novel approach Resonantly Suppressed Diffraction (RSD), which can quantify smallest deviations of atomic positions from the ideal structure to picometer accuracy. As with all synchrotron methods under resonant scattering conditions, the local electronic system of an atomic species is excited by specifically selected wavelengths of the X-ray spectrum. RSD considers the energy-dependent intensity response of Bragg reflections near an absorption edge, with special focus on an intensity minimum caused by destructive interference, which is highly sensitive to smallest deviations of the atomic order. Thus, the method offers an innovative approach for the characterization of dynamic processes and phase transformations under the influence of external parameters such as temperature, mechanical stress, and electric or magnetic fields. The new method is suitable for questions from chemical crystallography, but also from material, geo-, bio- and environmental sciences. RSD offers a unique opportunity to investigate defects in crystalline solids as well. Their crystalline near-order determines a variety of technically relevant properties. Precise knowledge and exact measurement of the atomic defect structure contributes significantly to a better understanding of materials and can optimize existing properties or create new ones through targeted modification ("defect engineering"). Thus, the RSD method is also important in the semiconductor industry, especially for data and electrochemical energy storage technologies. The approach was successfully applied to the structural elucidation of the migration-induced field-stabilized polar (MFP) phase in strontium titanate SrTiO3. After this first major success, further topics were investigated in the project, including temperature-dependent phase transformations in SrTiO3 volume crystals, and the mechanism of MFP phase formation and regression on the micrometer scale. To test the limits of the method, a ferroelectric low- temperature phase in YMn2O5 was selected, which has more than ten times as many structural degrees of freedom as SrTiO3 and which has not yet been completely determined. A suitable strategy for the determination of atomic displacements required a well-considered selection of reflections realized by systematic simulations in advance, as well as a step-wise refinement first addressing the dynamic displacements of the paraelectric and then the static displacements of the ferroelectric phase. In the completed project, many interesting scientific questions were successfully addressed and the method and dedicated sample environment were significantly further developed.
Publications
- Applications of resonant hard x-ray diffraction for characterization of structural modifications in crystals, Dissertation, TU Bergakademie Freiberg (2017)
C. Richter
- Strontium titanate: From symmetry changes to functionality, Cryst. Res. Technol. 52, 1600222 (2017)
H. Stöcker, J. Hanzig, M. Zschornak, E. Mehner, S. Jachalke, C. Richter, F. Hanzig, F. Meutzner, T. Leisegang, D. C. Meyer
(See online at https://doi.org/10.1002/crat.201600222) - Analysis of the defect clusters in congruent lithium tantalate, Phys. Rev. Materials 2, 013804 (2018)
A. Vyalikh, M. Zschornak, T. Köhler, M. Nentwich, T. Weigel, J. Hanzig, R. Zaripov, E. Vavilova, S. Gemming, E. Brendler, D. C. Meyer
(See online at https://doi.org/10.1103/PhysRevMaterials.2.013804) - Picometer polar atomic displacements in strontium titanate determined by resonant X-ray diffraction, Nat. Commun. 9, 178 (2018)
C. Richter, M. Zschornak, D. Novikov, E. Mehner, M. Nentwich, J. Hanzig, S. Gorfman, D. C. Meyer
(See online at https://doi.org/10.1038/s41467-017-02599-6) - Resonantly suppressed diffraction – Probing structural distortions with sub-picometer spatial resolution, REXS 2019 – 4th International Conference on Resonant Elastic X-ray Scattering, Brookhaven, NY, USA (2019)
M. Zschornak, C. Richter, D. Novikov, M. Nentwich, T. Weigel, D. C. Meyer
- Structure variations within RSi2 and R2TSi3 silicides. Part I Structure overview, Acta Cryst. B, 76, 177 (2020)
M. Nentwich, M. Zschornak, M. Sonntag, R. Gumeniuk, S. Gemming, T. Leisegang, D. C. Meyer
(See online at https://doi.org/10.1107/s2052520620001043) - Structure variations within RSi2 and R2TSi3 silicides. Part II Structure driving factors, Acta Cryst. B
M. Nentwich, M. Zschornak, M. Sonntag, R. Gumeniuk, S. Gemming, T. Leisegang, D. C. Meyer
(See online at https://doi.org/10.1107/s2052520620003893) - Struktur und Eigenschaften der Seltenerd-Übergangsmetall-Silizide, Dissertation, TU Bergakademie Freiberg (2020)
M. Nentwich
- X-ray diffraction using focused-ion-beam-prepared single crystals, J. Appl. Cryst. 53(3) (2020)
T. Weigel, C. Funke, M. Zschornak, T. Behm, H. Stöcker, T. Leisegang and D. C. Meyer
(See online at https://doi.org/10.1107/s1600576720003143)
