The effect of Fe content on dielectric and relaxation characteristics in TbFexMn1-xO3

Various ceramic composites of TbFexMn1-xO3 (x = 0, 0.25, 0.5, 0.75) were prepared by conventional solid-state reaction. The electrical properties such as dielectric constant, loss and resistivity have been studied as a function of the temperature from 77 to 400 K and the frequency from 0.1 to 1000 kHz. The XRD and SEM for these four types of materials show similar patterns with the increasing of the Fe concentration. Instead, the dielectric constant and loss for them will change dramatically in properties. The figures of all samples display two distinct semicircular arcs in the Nyquist plots at 300 K and all figures located at high frequency region are independent of the applied ac biases. By analyzing the values of the activation energy, it is found that the origin of the relaxation in dielectric loss is related to the changing of octahedral structure.