Observation of magnetoelectric coupling and local piezoresponse in modified (Na_(0.5)Bi_(0.5))TiO_~(3-) BaTiO_3-CoFe_2O_4 lead-free composites

摘要

Lead-free particulate multiferroic composites of [0.94(Na_(0.5)Bi_(0.5))TiO_3-0.06 BaTiO_3]:(Co_(0.6)Zn_(0.4))-(Fe_(1.7)Mn_(0.3))O_4 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 λ_(11) =-10.4 and λ_(12) = 5.3 ppm and piezomagnetic coefficient dλ_(11)/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.