Effect of Surface Layers on the Coercive Field, Spontaneous Polarization and Dielectric Constant of Triglycine Selenate

Abstract

The coercive field and spontaneous polarization have been measured as a function of temperature (−10°C to 22°C) for different thicknesses (about 2 mm to 0.5 mm) of triglycine selenate crystals. The thickness dependent dielectric constant has also been measured at frequencies 1 kHz, 10 kHz and 100 kHz. The coercive field is found to be inversely proportional to the thickness of the sample. The spontaneous polarization has been found to decrease with decreasing thickness and the effect is most pronounced at smaller thicknesses. The results can be explained by assuming a single homogeneous surface layer of low dielectric constant. However, the numerical values of surface layer thickness estimated from the coercive field measurements are two order of magnitude higher than those derived from thickness dependent dielectric constant measurements.