Polarization reversal and ferroelectric domain structure observed in electroded cesium dihydrogen phosphate crystals using an X-ray anomalous dispersion effect

We have carried out an X-ray intensity measurement and X-ray topography on electroded b plates of ferroelectric cesium dihydrogen phosphate, CsH2PO4 (CDP), using a synchrotron radiation with a wavelength of 2.482 A above the Cs L3-absorption edge. We have found that integrated intensities I(150) and I(1-bar5-bar0) show an anomalously large breakdown of Friedel's law, I(150)/I(1-bar5-bar0)=10.4 at 125 K, and display a ferroelectric hysteresis loop. The hysteresis loop determines that spontaneous polarization is antiparallel to the b axes set in both ferroelectric crystal structures related by inversions. The (150) diffraction topography shows that a single domain turns into a lamellar domain structure without fractal aspects after short-circuiting the b plate. The atomic displacement associated with polarization reversal is shown in a crystal structure model of 180deg domains observed in the X-ray topography. (author)