Observation of magnetoelectric coupling and local piezoresponse in modified (Na0.5Bi0.5)TiO3–BaTiO3–CoFe2O4 lead-free composites

Abstract

Lead-free particulate multiferroic composites of [0.94(Na_0.5Bi_0.5)TiO₃–0.06 BaTiO₃]:(Co_0.6Zn_0.4)(Fe_1.7Mn_0.3)O₄ were synthesized and magnetoelectric (ME) properties were studied. X-ray diffraction and microstructural studies indicated the formation of a two-phase composite system without any impurities. The shift of Raman modes corresponding to ferroelectric and ferrite phases was assigned to the induced strain amid the formation of a two-phase system, in relation to the fraction of each phase in the samples. A strong local piezoresponse and hysteresis loops observed for composites established the ferroelectric properties at a nanoscale. Magnetostriction measurements revealed values of λ₁₁ = −10.4 and λ₁₂ = 5.3 ppm and piezomagnetic coefficient dλ₁₁/dH = −0.0087 ppm Oe⁻¹ at 0.45 kOe for a composite with a ferrite concentration of 35 mol%. A maximum change of 18.5% in magnetization after electrical poling indicates a strong magnetoelectric response of the present composites followed by a direct ME coefficient of 8.2 mV cm⁻¹ Oe⁻¹. Our studies point to the fact that the present multiferroic composites having strong ME coupling are useful for lead-free electronic applications.