Transport and dielectric properties of nanocrystallite cobalt ferrites: Correlation with cations distribution and crystallite size

Nanocrystallite Cobalt ferrites (NCFs) were synthesized at different pH values in the range from . 09.0 to 13.3 through wet chemical synthesis by a co precipitation method. The crystal structure and cations distribution as a function of pH values were studied from X-ray diffraction data. The crystallite sizes of the produced samples were in the range between 31.86 and 42.83 nm and the lowest value equal to 31.86 nm for the sample prepared at pH approximate to 11. Obtained cations distributions were found in good agreement with the matching between experimental and theoretical lattice constants. The inversion degree (x) of NCFs varies with pH values and the formula for the sample prepared at pH approximate to 11 was (Co0.27Fe0.73)(A)[Co0.73Fe1.27]O-B(4) with x = 0.73. SEM images analyzed by using image J program and they show that the particles have nearly a homogeneous distribution, spherical shape and agglomerated form. The value of activation energy ranges from 0.433 to 0.498 eV and the values of resistivity lie in the range 1.6 x 10(5) Omega m to 6.1 x 10(6) Omega m. The AC electrical conductivity increases with the increase in frequency. The sample fabricated at pH approximate to 11 has the largest value of the AC electrical conductivity and the smallest value of the dielectric constant. The AC electrical conductivity and the dielectric constant of the NCFs are based on the grains and grain boundaries.