Synthesis and Characterization of Magnetoelectric Nanocomposites

A simple citrate gel process was used to prepare nanocomposites of xCuFe2O4–(1−x)BiFeO3 (henceforth, CFBF) and xNi0.75Co0.25Fe2O4-(1-x)BiFeO3 (henceforth, NCFBF) with x=0.1, 0.2, 0.3 and 0.4. The phase was found to be formed at 500 °C and 700 °C for CFBF and NCFBF respectively. TEM observation showed that the average particles size is around 40 nm. The variation of the dielectric constant and the dielectric loss with frequency showed dispersion in the low frequency range. All the samples exhibit strong magnetic characteristics. The coercivity and squareness increased with the increase in annealing temperature and were maximum for samples annealed at 500ºC and 700ºC for CFBF and NCFBF nanocomposites, respectively, and further decrease in coercivity is attributed to decrease in aspect ratio and pinning effects in the nanocrysatllites. The ME coefficient αE showed strong dependence on HBias and maximum value of ME coefficients were 303 and 309 mV/cm Oe at magnetic field frequency of 50 kHz for CFBF and NCFBF nanocomposites respectively. The large values of ME coefficients are attributed to low coercivity, large magnetization and small crystallite size of constituent phases.