Polarization Reversal in Tri-Glycine Fluoberyllate and Tri-Glycine Sulfate Single Crystals

Abstract

Time and field dependence of switching current at room temperature was studied for tri-glycine fluoberyllate as well as for tri-glycine sulfate. It is shown that the theory describing polarization reversal in BaTiO3 c-domain crystals based on observed time and field dependence of polarization P=f(E,t) developed by the authors is applicable. Activation field α and mobility μ appearing in the basic equation were determined for tri-glycine fluoberyllate (TGFB) as well as for tri-glycine sulfate (TGS). For both materials, α, as well as μ was found to be independent of crystal thickness indicating that no skin properties are involved. The value of α for TGFB and TGS is lower by a factor of at least 2.5 and 3, respectively, than for BaTiO3. Compared to values for BaTiO3, the value of μ for TGFB and TGS is lower for thick crystals and higher for relatively thin crystals (δ<8×10−3 cm). Switching conductivity for both materials is given. Both TGFB and TGS were investigated under various pulsed conditions and no fatigue effect was found. The hysteresis losses in both materials are less by a factor of about 10 than those for BaTiO3.