Electrical, magnetic and Mössbauer properties of cadmium - cobalt ferrites prepared by the tartarate precursor method

Abstract

Six samples of the system Cd1−xCoxFe2O4 were prepared by the tartarate precursor method with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0. The formation of ferrispinels were studied by X-ray powder diffraction, infrared spectroscopy, electrical conductivity, thermoelectric power, magnetic hysteresis, initial magnetic susceptibility and Mossbauer spectroscopy. The data of the temperature variation of the direct current electrical conductivity showed a definite kink (∼390°C) except x = 0.0 and 0.2, which corresponds to the ferrimagnetic to paramagnetic transitions. Magnetic properties of the samples with x ≥ 0.6 showed definite hysteresis loops. The observed low magnetic moment can be explained in terms of the non collinear spin arrangement. A well defined hyperfine Zeeman spectra are observed for samples with x ≥ 0.6 at room temperature and resolved into two sextets corresponding to octahedral and tetrahedral sites. The electrical, magnetic and Mossbauer properties suggest that, a canted spin arrangement upto x = 0.8 and Neel's configuration above this composition. The probable ionic configuration for the system is suggested as $$\left( {{\text{Cd}}_{{\text{1 - }}x}^{{\text{2 + }}} {\text{Fe}}_x^{3 + } } \right)_{\text{A}} \left[ {{\text{Fe}}_{{\text{2 - }}x}^{{\text{3 + }}} {\text{Co}}_x^{{\text{2 + }}} } \right]_{\text{B}} {\text{O}}_{\text{4}}^{{\text{2 - }}} .$$