Synthesis and characterization of La0.75Ca0.15Sr0.05Ba0.05MnO3–Ni0.9Zn0.1Fe2O4 multiferroic composites

• Novel manganite–ferrite composites were synthesized by solid state reaction method.
• Low frequency dielectric dispersion observed due to interfacial polarization.
• Complex impedance showed semicircular arc due to the grain boundary resistance.
• Linearity in logω2logω2 versus logσAClogσAC plot confirmed the conduction is due to small polaron hopping.
• The maximum ME voltage coefficient of ~40 mV Oe−1 cm−1 observed for x=0.8.

In the present work, we report on structural, dielectric, impedance spectroscopic studies and magnetoelectric properties of (1−x) La0.75Ca0.15Sr0.05Ba0.05MnO3 (LCSBMO)+(x) Ni0.9Zn0.1Fe2O4 (NZFO) (x=0.0, 0.1, 0.2, 0.4, 0.6, 0.8 and 1.0) composites. The composites were prepared by the solid state reaction route. The coexistence of a cubic spinel NZFO phase and a tetragonal LCSBMO phase in the composites is confirmed by the X-ray diffraction measurement. Scanning electron microscopy images reveal that NZFO particles were distributed non-uniformly with some porosity in the LCSBMO matrix. Frequency dependent dielectric constant shows usual dielectric dispersion behavior, which may be attributed to the Maxwell–Wagner type interfacial polarization. At higher frequencies (≥105 Hz), due to electronic and ionic polarizations only, the dielectric constant is independent of frequency. Complex impedance shows semicircular arc due to the domination of grain boundary resistance and electric modulus confirms the presence of hopping conduction. The AC conductivity (σACσAC) obeys the power law and the linearity of logω2logω2 versus logσAClogσAC plots indicates that the conduction mechanism is due to small polaron hopping. Low frequency dispersion in permeability is due to domain wall motion and the frequency stability of permeability indicates that the arrangement of the magnetic moment in the polarization process can keep up with the external field. The maximum magnetoelectric voltage coefficient of ~40 mV Oe−1 cm−1 for x=0.8.