Scanning X-ray nanodiffraction from ferroelectric domains in strained K0.75Na0.25NbO3 epitaxial films grown on (110) TbScO3

Martin Schmidbauer; Michael Hanke; Albert Kwasniewski; Dorothee Braun; Leonard von Helden; Christoph Feldt; Steven John Leake; Jutta Schwarzkopf

doi:10.1107/S1600576717000905

Scanning X-ray nanodiffraction from ferroelectric domains in strained K_0.75Na_0.25NbO₃ epitaxial films grown on (110) TbScO₃

J Appl Crystallogr. 2017 Feb 17;50(Pt 2):519-524. doi: 10.1107/S1600576717000905. eCollection 2017 Apr 1.

Authors

Martin Schmidbauer¹, Michael Hanke², Albert Kwasniewski¹, Dorothee Braun¹, Leonard von Helden¹, Christoph Feldt¹, Steven John Leake³, Jutta Schwarzkopf¹

Affiliations

¹ Leibniz-Institut für Kristallzüchtung, Max-Born-Strasse 2, Berlin 12489, Germany.
² Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin, Hausvogteiplatz 5-7, Berlin 10117, Germany.
³ ESRF - The European Synchrotron, 71 Avenue des Martyrs, Grenoble Cedex 9, CS-40220, 38043, France.

Abstract

Scanning X-ray nanodiffraction on a highly periodic ferroelectric domain pattern of a strained K_0.75Na_0.25NbO₃ epitaxial layer has been performed by using a focused X-ray beam of about 100 nm probe size. A 90°-rotated domain variant which is aligned along [1[Formula: see text]2]_TSO has been found in addition to the predominant domain variant where the domains are aligned along the [[Formula: see text]12]_TSO direction of the underlying (110) TbScO₃ (TSO) orthorhombic substrate. Owing to the larger elastic strain energy density, the 90°-rotated domains appear with significantly reduced probability. Furthermore, the 90°-rotated variant shows a larger vertical lattice spacing than the 0°-rotated domain variant. Calculations based on linear elasticity theory substantiate that this difference is caused by the elastic anisotropy of the K_0.75Na_0.25NbO₃ epitaxial layer.

Keywords: KxNa1−xNbO3; X-ray nanodiffraction; ferroelectric domains; strained epitaxial films.