Enhanced magnetoelectric coefficients in Na0.5Bi0.5TiO3–CoFe2O4 particulate composites prepared from pre-sintered constituents

Leveraging the strain transfer at the interface between self-composite CoFe2O4 embedded in pre-sintered Na0.5Bi0.5TiO3 ceramics matrix for the enhancement of magnetoelectric voltage coefficient

“…h 7 ) However, more than five modes are considered as Raman active in all the samples among the 39 modes: 2A 1g , E g, and 3T 2g . The observed phonon modes are at 187 cm −1 , 305 cm −1 , 477 cm −1 , 557 cm −1 , 601 cm −1 , and 690 cm −1 for CFO-b and almost similar for CFO-n which agrees with literature [17,21]. The shifting of the Raman peak towards the lower frequency side is commonly observed in the nano-structured oxides due to a lack of long-range order because the small particle size hinders phonon propagation and hence induces a shift from the Brillouin zone center which makes all the phonons to shift.…”

“…Bulk cobalt ferrite (CFO-b) was prepared by the solid-state method as reported earlier [17]. The cobalt ferrite self-composites were prepared by thoroughly mixing the as-prepared CFO-n and CFO-b powders in a ratio of 50:50.…”

“…The increased magnetostrictive phase (both nano and bulk grains of CFO) causes a stronger magnetization vector which increases the strain transfer between the phases. The maximum value [17]. The magnetostriction coefficient, magnetization of the magnetic phase, and piezoelectric coefficient of the piezoelectric phase contribute to the improved ME effect in the composite.…”

“…Also, the increased interfacial area can provide a route for increased ME values [35,36]. The twice-grain-sized NBT embedded with CFO grains provides enhanced ME values [17].…”

“…Hence it is expected to obtain a particulate composite without any defects. The ME voltage coefficient has been reported so far in NBT-CFO composite which are 72.72 μV/cm Oe [16], 8.2 mV cm −1 Oe [5] 18.9 mV cm −1 Oe [17]. The highest value of 18.9 mV cm −1 Oe is achieved due to the pre-sintering of the constituent phases which results in no intermediate phase formation and composite sintering at a temperature lower than the sintering of the individual phases.…”