Identification of inversion domains in KTiOPO{sub 4}via resonant X-ray diffraction

• Published in: Acta crystallographica. Section A, Foundations and advances Vol. 71; no. Pt 4
• Main Authors: Fabrizi, Federica, Thomas, Pamela A., Nisbet, Gareth, Collins, Stephen P.
• Format: Journal Article
• Language: English
• Published: United Kingdom 14-05-2015
• Subjects: ABSORPTION; BEAMS; BRAGG REFLECTION; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COUPLING; DISTRIBUTION; FERROELECTRIC MATERIALS; POTENTIALS; SPATIAL RESOLUTION; SPECTRA; SYMMETRY; SYNCHROTRON RADIATION; SYNCHROTRONS; X-RAY DIFFRACTION
• ISSN: 2053-2733; 2053-2733
• DOI: 10.1107/S2053273315007238

The identification and high-resolution mapping of the absolute crystallographic structure in multi-domain ferroelectric KTiOPO{sub 4} is achieved through a novel synchrotron X-ray diffraction method. On a single Bragg reflection, the intensity ratio in resonant diffraction below and above the Ti absorption K edge demonstrates a domain contrast up to a factor of ∼270, thus implementing a non-contact, non-destructive imaging technique with micrometre spatial resolution, applicable to samples of arbitrarily large dimensions. A novel method is presented for the identification of the absolute crystallographic structure in multi-domain polar materials such as ferroelectric KTiOPO{sub 4}. Resonant (or ‘anomalous’) X-ray diffraction spectra collected across the absorption K edge of Ti (4.966 keV) on a single Bragg reflection demonstrate a huge intensity ratio above and below the edge, providing a polar domain contrast of ∼270. This allows one to map the spatial domain distribution in a periodically inverted sample, with a resolution of ∼1 µm achieved with a microfocused beam. This non-contact, non-destructive technique is well suited for samples of large dimensions (in contrast with traditional resonant X-ray methods based on diffraction from Friedel pairs), and its potential is particularly relevant in the context of physical phenomena connected with an absence of inversion symmetry, which require characterization of the underlying absolute atomic structure (such as in the case of magnetoelectric coupling and multiferroics)