Effect of yttrium doping on the structure, dielectric multiferroic and magnetodielectric properties of Bi5Ti3FeO15 ceramics

Multiferroic Bi_5−xY_xTi₃FeO₁₅ (BYTF-x, x = 0, 0.1, 0.3, 0.5, 0.7) ceramics were synthesized through the conventional solid-state reaction. The structure, dielectric, multiferroic and magnetodielectric properties of BYTF-x were investigated in detail. X-ray diffraction confirmed that all the samples were layered Aurivillius structure. Upon increasing Y content, the grain size of samples slightly decreases. The dielectric permittivity increased with Y doped. The Y doping has no effect on microstructural changes of plate-like grains which verified though field-emission scanning electron microscopy. The minimum remanent polarization (2P_r = 2.48 μc/cm²) was observed in BYTF-0.3 ceramic and the maximum magnetodielectric coefficient value of 1.23% was obtained in BYTF-0.3 ceramic perhaps result from the coexistence of Fe²⁺ and Fe³⁺. Additionally, weak ferromagnetic is only found in BYTF-0.3 ceramic. The ferromagnetism can be attributed to ferromagnetic double exchange interactions (Fe²⁺–O–Fe³⁺) and the spin canting of tilting FeO₆ octahedra via the Dzyaloshinskii–Moriya interaction. These results indicate that Y doping Aurivillius phase may be the potential candidates for exploring superior room-temperature multiferroics.