Origin of magnetic, magnetoelectric effect and the influence of reentrant ferroelectric phase on the structural and multiferroic properties of Dy3+-Fe3+ co-substituted BaTiO3 ceramics

Retain of phase pure ferroelectric tetragonal phase (P4mm) achieved from the coexistence of paraelectric hexagonal phase (P6₃/mmc) + ferroelectric phase without the loss of polarisation and magnetization under the Dy³⁺-Fe³⁺ co-substitution on BaTiO₃, Ba_1-yDy_yTi_1-xFe_xO₃ (x = 0.05; y = 0; 0.005; 0.010 and 0.015) ceramics. A small amount of Dy substitution enhances the inhibition of vacancy formation and suppresses the defect concentration through the decrease of the hexagonal phase. The unexpected ferromagnetic nature in the non-magnetic tetragonal phase in y = 0.015 ceramics unambiguously depends on the formation of the paramagnetic defect, Ti³⁺ for the charge compensation process that induces magnetic moment. The observed ferromagnetic nature in y = 0.01 ceramics originated from the Fe³⁺-O²⁻-Fe³⁺ super-exchange and Dy³⁺-O²⁻-Dy³⁺ interactions which are stronger than the magneto-crystalline anisotropy (y = 0.015). For the first time, multiferroic properties (magnetodielectric and magnetoelectric) were reported in this work. The magnetoelectric coupling effect originated from the co-contribution of magnetocrystalline anisotropy due to spin–orbit interaction through symmetry breaking and microstrain.