Effect of polaron hoping on electrical properties of magneto electric composites

The Co_0.7-xNi_xMn_0.3Fe₂O₄ (CNMFO) ferrites with x = 0.00, 0.05, 0.10 and 0.15, PbZr_0.52Ti_0.48O₃ (PZT) ferroelectric and 30% CNMFO – 70% PZT magnetoelectric (ME) composites were synthesized by double sintering ceramic method. The XRD confirmed the pure phase formation of all compositions of ferrite, ferroelectric and ME composites. All compositions of ferrites, ferroelectric and ME composites show negative temperature coefficient of resistance (NTCR) confirming the semiconducting behavior, though the conduction mechanism is quite different than known semiconductors such as, silicon and germanium. The conduction, due to electron hoping in semiconductors against polaron hoping in ferrites is explained. The effect of cation distribution on resistivity of ferrite phase is also discussed. Thus, the effect of polaron hoping as well as cation distribution has been discussed on resistivity and dielectric constant of ferroelectric and ME composites. The effective resistance of ME composites due to combined resistance of the constituent phases has been studied.