OBSERVATION OF PERIODIC DOMAIN INVERSION IN PERIODICALLY POLED LINBO3BY HIGH-RESOLUTION TOPOGRAPHY

Periodic domain inversion in an electric-field poled LiNbO3 crystal ha s been studied using high-resolution multiple-crystal multiple-reflect ion X-ray diffraction topography. Fine linear contrast with spacings t hat correspond to the lateral dimensions of the periodic pattern has b een observed by the choice of an appropriate diffraction mode to provi de high spatial resolution and is shown to arise essentially from stra ins at the domain walls. The origin of the strain contrast at the doma in walls is suggested primarily to be the result of the domain-inversi on processing via the converse piezeoelectric effect. A structural mod el 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 em ploying a different diffraction mode [Hu, Thomas & Webjorn (1995). J. Phys. D, 28, A189-A194].