Structural, electrical and magnetic properties of cadmium substituted nickel-copper ferrites

摘要

Polycrystalline ferrites with the general formula Ni_(0.95-x)Cd_xCu_(0.05)Fe_2O_4 in which x varies from 0.1 to 0.3 were synthesized by standard double sintering ceramic technique. The existence of single phase cubic spinel structure of ferrites was confirmed from XRD measurement. Surface morphology and compositional features were studied by SEM and EDX measurements. Absorption bands observed in FT1R spectra at 600 cm~(-1) (v_1)and 410 cm~(-1) (v_2) corresponds to vibrations of tetrahedral and octahedral complexes respectively. In the dc conductivity measurements the decrease of dc resistivity with increase of temperature indicates the semiconducting nature of ferrites. The dielectric measurement of the samples at room temperature studied in the frequency range 20 Hz to 1 MHz shows dispersion in the low frequency region and remains constant at high frequency region. However, the small polaron hoping type of conduction mechanism was inferred from the linear increase of ac conductivity. The magnetic properties of ferrites such as saturation magnetization, magnetic moment and Y-K angles was estimated as a function of cadmium content by VSM technique. The smaller value of Mr/Ms reveals the existence of multidomain (MD) particles in the ferrite samples.