Dielectric Relaxation of Manganese Modified Bi6Fe2Ti3O18 Aurivillius Type Ceramics

The five-layer Aurivillius type structures with the general chemical formula Bi₅Fe_2-xMnxTi₃O₁₈, where x = 0, 0.6, 1.2 have been synthesized and tested. The SEM studies showed a significant increase in grain size in the manganese-modified Aurivillius type ceramic material (for x=1.2). The increase in the amount of manganese ions (Mn³⁺) affects the decrease in the temperature at which the relaxation processes take place. Namely from 525 K (1 kHz) and 725 K (1 MHz) for BFT sample (x=0) to 355 K (1 kHz) and 565 K (1 MHz) for BFM12T sample (x=1.2). Using the Arrhenius’s law and the Vogel-Fulcher’s relationship the activation energy (E_a) and the relaxation time have been calculated. The value of E_a increases with the increase of the Mn amount from 0.737 eV (for x=0) to 0.915 eV (for x=1.2).