Structural, AC, and DC magnetic properties of Zn1−xCoxFe2O4

Structural, AC and DC magnetic properties of polycrystalline Zn1−xCoxFe2O4 (x=0.2, 0.4) samples sintered at various temperatures (1100–1300 °C), and various dwell times (0.2–15 h) have been investigated thoroughly. The bulk density of the Zn0.60Co0.40Fe2O4 samples increases as the sintering temperature (Ts) increases from 1100 to 1250 °C, and above 1250 °C the bulk density decreases slightly. The Zn0.80Co0.20Fe2O4 samples show similar behavior of changes to that of Zn0.60Co0.40Fe2O4 samples except that the bulk density is found to be highest at 1200 °C. The DC magnetization as a function of temperature curves show that the Zn0.60Co0.40Fe2O4 sample is ferrimagnetic at room temperature while the Zn0.80Co0.20Fe2O4 sample is paramagnetic at room temperature. The Tc of Zn0.80Co0.20Fe2O4 sample is found to be 170 K from DC magnetization measurement. Separate measurement (AC magnetization), initial permeability as a function of temperature shows that the Tc of the Zn0.60Co0.40Fe2O4 sample is 353 K. Slight variation of Tc is observed depending on sintering condition. The initial permeability for the Zn0.60Co0.40Fe2O4 composition sintered at 1250 °C is found to be maximum.