Magneto-electric characterization of x (Na_0.5K_0.5)_0.94Li_0.06NbO₃- (1-x) NiFe₂O₄ composite ceramics

Lead free magneto-electric composites of Sodium Potassium Lithium Niobate-Nickel Ferrite (NKLN-NFO) with different molar weight percent of NKLN are prepared by solid state reaction involving co-precipitation and sintering. Four different compositions of x NKLN-(1-x) NFO have been selected to perform systematic studies on their magneto-electric properties. The dielectric constant of dense samples is measured as functions of frequency, temperature and external magnetic field. Dielectric constant is found to decrease after poling, and show resonance/relaxation peaks in dielectric properties at certain frequencies. AC conductivity is determined to understand the mechanism of conductivity. Changes in dielectric constant with applied magnetic field (or magneto-dielectric effect) are also reported. The magneto-electric coefficient for the composition with x = 0.8 is found to be 2.32 × 10⁻² V/cm-Oe while with x = 0.85 it is 2.43 × 10⁻² V/cm-Oe. These are the highest values reported so far for a lead free composite material prepared by normal solid state reaction cum sintering route. We find that x NKLN- (1-x) NFO exhibits sufficiently high room temperature magneto-electric coefficient suitable for applications compared to other lead free composites prepared by solid state route.