Phase transition of KDP observed by Resonant X-ray Diffraction at forbidden reflections

Workshop on Resonant Elastic X-ray Scattering in Condensed Matter 2013

Beutier, G.^1,2 ; Collins, S.P.^2 ; Ovchinnikova, E.N.^3 ; Nisbet, G.^2 ; Dmitrienko, V.E.^4

SIMaP, Grenoble Institute of Technology-CNRS, Grenoble Alpes University, France^1

Diamond Light Source, Harwell Science and Innovation Campus, 0X11 ODE, United Kingdom^2

Department of Physics, Moscow State University, 119899 Moscow, Russia^3

A.V. Shubnikov Institute of Crystallography, 119333, Moscow, Russia^4

关键词: Bragg reflection;    Dipole approximation;    Electric-dipole approximation;    Energy spectra;    Ferroelectric phase;    Forbidden reflections;    Resonant x-ray diffraction;    Sudden change;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/519/1/012006/pdf
DOI  :  10.1088/1742-6596/519/1/012006

来源: IOP

【 摘 要 】

We report observations of space-group-forbidden Bragg reflections in Potassium (KH2PO4), at the potassium K edge. We find clear evidence for a transition from one class of space-group-forbidden reflections, where scattering is ruled out by the electric dipole approximation, to a second class, in the ferroelectric phase, where scattering can proceed due to resonant anisotropy within the dipole approximation. The change of symmetry is clearly evidenced by the sudden change of intensity and energy spectrum of the forbidden reflections.