Magnetic ion oxidation state dependent magnetoelectric coupling strength in Fe doped BCT ceramics

Abstract

Polycrystalline samples of Ba_0.96Ca_0.04Ti_0.91Fe_0.09O₃ were prepared using a conventional solid state reaction route with different Fe starting precursors (Fe₂O₃, Fe₃O₄). The Rietveld refined XRD data confirmed the phase purity and tetragonal crystal structure of both the samples. The average grain size measured using SEM was ≈0.40 μm in both the samples. XPS analysis confirmed the presence of only Fe²⁺ and both Fe²⁺/Fe³⁺ in Fe₂O₃ and Fe₃O₄ doped BCT samples. The P_r and M_r values have been measured to be 1.34 μC cm⁻², 2.88 μC cm⁻² and 0.0015 emu g⁻¹ and 0.135 emu g⁻¹ in Fe₂O₃ and Fe₃O₄ doped BCT samples, respectively. The Fe₃O₄ doped samples exhibit much better M-E coupling (≈22%) as compared to Fe₂O₃ (≈7%) doped BCT samples. The results obtained hence suggest that Fe₃O₄ doping in BCT is better suited for multiferroic applications.