Observation of Periodic Domain Inversion in Periodically Poled LiNbO₃ by High-Resolution Topography

Periodic domain inversion in an electric field poled LiNbO₃ crystal has been studied using high-resolution multiple-crystal multiple-reflection X-ray diffraction topography. Fine linear contrast with spacings that correspond to the lateral dimensions of the periodic pattern has been observed by the choice of an appropriate diffraction mode to provide high spatial resolution and is shown to arise essentially from strains at the domain walls. The origin of the strain contrast at the domain walls is suggested primarily to be the result of the domain-inversion processing via the converse piezeoelectric effect. A structural model for the domain inversion that is based on a pseudosymmetry argument is invoked in order to quantify the ionic displacements for twinning. These results are compared with those obtained in a previous study employing a different diffraction mode [Hu, Thomas & Webjörn (1995). J. Phys. D, 28, A189-A194].