Quantitative x-ray Bragg diffraction topography of periodically domain-inverted LiNbO3

Periodic domain inversion in a ferroelectric material (lithium niobate) has been studied using high-resolution x-ray diffraction topography. A domain- inverted structure of period 30 mu m was fabricated in a LiNbO3 crystal wit h a thickness of 300 mu m via electric-field poling. The synchrotron-radiat ion x-ray experiments were carried out at the ESRF micro-fluorescence, imag ing and diffraction beamline (ID22). The experimental topograms and numeric al simulations show that the image contrast can be explained in terms of a phase shift of the polarizability coefficient, chi(h), in the domain-invert ed region relative to the non-inverted part. This phase shift, 1.72 pi, was found to be equivalent to the reflection, 00 (6) over bar, from the domain -inverted part of the structure rather than to the reflection, 006, from th e non-inverted part. The numerical simulation shows that the width of the t ransition region between inverted and non-inverted domains (domain walls) i s 0.3 mu m.