Ba_4Ln_2Fe_2Nb_8O_(30) (Ln = Eu, Gd) Ferroelectric Ceramics

摘要

Ba_4Ln_2Fe_2Nb_8O_(30) (Ln = Eu and Gd) ceramics were synthesized by high temperature solid state reaction. The phase composition, microstructure, dielectric and ferroelectric properties of them were characterized. Both ceramics adopt filled tetragonal tungsten bronze structure at room temperature. The diffusive phase transitions were observed for Ba_4Eu_2Fe_2Nb_8O_(30) and Ba_4Gd_2Fe_2Nb_8O_(30) around 163℃ and 150℃, respectively. Ba_4Eu_2Fe_2Nb_8O_(30) and Ba_4Gd_2Fe_2Nb_8O_(30) ceramics are classical ferroelectrics at room temperature and show high dielectric constant of 118 and 160 and low dielectric loss 0.022 and 0.054 at 1 MHz, respectively. The remnant polarizations (2P_r) are 3.9μC/cm~2 for Ba_4Eu_2Fe_2Nb_8O_(30) and 1.71 μC/cm~2 for Ba_4Gd_2Fe_2Nb_8O_(30).