Effect of PbTiO3 concentration on structural, paramagnetic resonance and magnetoelectric properties of PbTiO3:SrFe12O19 multiferroic nanocomposites

Abstract

Polycrystalline multiferroic nanocomposites of compositions (x) PbTiO3 – (1-x) SrFe12O19 where x = 0.10, 0.20, 0.30 and 0.50 are prepared by the solid state solution method and characterized their structural, magnetic and magnetoelectric properties to establish correlation among them for use in chemical sensors application. XRD patterns exhibit the broadening of diffraction peaks with PbTiO3 concentration due to the distortion induced by Pb2+ and Ti4+ ions doping in SrFe12O19 lattice. The asymmetrical peak broadening and peak positions shift in Raman spectra arise from phonon confinements and compressive stress developed in SrFe12O19 lattice by the addition of PbTiO3. The role of PbTiO3 concentration on spins dynamics and magnetic interactions in these multiferroic nanocomposites has been inferred from Electron Paramagnetic Resonance (EPR) parameters. EPR spectra depict the ferromagnetic nature of nanocomposites and higher g-values as compared to free electron g – value showed the strong magnetic interactions among grains. The decrease in peak-to-peak line width, g-value, spin concentration and spin-spin relaxation time constant for x = 0.10, 0.20, 0.50 concentrations of PbTiO3 in nanocomposites reveals the decrease in magnetic interactions. While for x = 0.30 analogue, the exceptional increase in all the parameters is due to grain growth in the form of rod like structures. Magnetoelectric coupling coefficient (αME) values exhibit maximum value 0.51 for x = 0.30 composition owing to magnetostriction and the increase in grain size for x = 0.30 as compared to other composition.