Dielectric, multiferroic and magnetodielectric properties of Co/Fe co-doped Bi₄Ti₃O₁₂ ceramics

Polycrystalline Bi₄Co_xFe_2xTi_3−3xO₁₂ (BC2FT) ceramics (0 ≤ x ≤ 0.4) were synthesized by conventional solid state reaction and their dielectric, multiferroic and magnetodielectric (MD) properties have been investigated. The XRD data results reveals that all samples possess a layered perovskite structure belonging to the n = 3 members of the Aurivillius family and a secondary phase of Bi₅Ti₃FeO₁₅ could be observed at higher concentrations. The average grain size is found to decrease with the increase of x. Permittivity values decrease with the content of Co and Fe increasing (0.1 ≤ x ≤ 0.4). BC2FT ceramics exhibit ferroelectric and weak ferromagnetic properties at room temperature. Room-temperature magnetodielectric (MD) and magnetodielectricloss effect were observed in all samples, resulting from the contributions of the magnetostriction effect. Furthermore, with the dopant content of Co and Fe increasing, the negative peaks shift to a lower frequency and the positive peak get the largest room-temperature MD response of 0.649% at 97.88 Hz with x = 0.4.