X-Ray Bragg Reflection and Infrared Absorption Topography of Ferroelectric NaNO₂

Abstract

X-ray diffraction topographic study of the partly electroded plates of ferroelectric NaNO₂ crystals (S. Suzuki and M. Takagi: J. Phys. Soc. Jpn 32 (1972) 1302) has revealed many small regions where the half way state of the rotational motion of NO₂ radicals at the time of the polarization reversal had been quenched. By making use of the sensitive dependence of infrared ν₂ absorption on the orientation of the NO₂ radicals, rotation angle of NO₂ at the regions was estimated through the topographic (point by point) measurements of the infrared absorption. Topographic coincidence between X-ray topographs and infrared absorption was confirmed. Present study is the first work which had detected orientational change of molecules in a single crystal by using infrared absorption measurements in cooperation with X-ray topography.