화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.174, 120-128, 2016
Nanostructural and lattice contributions to multiferroism in NiFe2O4/BaTiO3
Multiferroic NiFe2O4/BaTiO3 (NFO/BTO) nanostructures (nanoparticles, nanorods, nanowires) were synthesized by chemical combustion (C), sol-gel (S) and hydrothermal (H) methods. XRD pattern shows tetragonal BTO and spinel NFO structure. The lattice distortion is enhanced with oriented growth in NFO/BTO grains to induce lattice strain. The shape and size of NFO/BTO nanostructures are described with optimized synthesize conditions. Fourier transform infrared spectra could evaluate organic extent after heating conditions in the samples and metal-oxygen bonds. The ferromagnetism in NFO/BTO is originated due to the fact that the mixed BTO phase acts as a non-magnetic defect, first hindering the growth of the magnetic domains in NFO and then also hindering the movement of the magnetic domains in ferrite under an external field. The defects/vacancies induced by shape/size effect result into variation in observed ferromagnetism. Significantly enhanced ferroelectricity is related with lattice distortion, interface mismatch, oriented growth and grain size/boundaries are given. Leakage current conduction mechanism to enhance ferroelectric behaviors is studied. Magnetoelectric coupling due to induced charges at grain boundaries in NFO/BTO interface is investigated by magneto-capacitance-dielectric measurement. The relative permittivity is decreased with applied dc magnetic field could induce negative magnetodielectric effect that depend to the combination to spinpair correlation of neighboring spins and the coupling constant. Dynamic magnetoelectric coupling was investigated, and the maximum value of longitudinal magnetoelectric coupling coefficient, alpha is 40.33 ps/m (alpha(ME) = 72.49 mV/cm Oe) observed in NFO/BTO nanowires. (C) 2016 Elsevier B.V. All rights reserved.