Investigation on electrical and magnetic properties of Mn0.50Zn0.50-xCUxFe2O4 ferrites

Abstract

Polycrystalline Mn0.50Zn0.50-xCuxFe2O4 (with x = 0.00, 0.02, 0.05, 0.08, 0.10, 0.15, 0.20, 0.25, 0.30) ferrites are prepared by conventional solid state reaction technique. Pelletand toroid-shaped samples are prepared from each composition and sintered at various temperatures (1200, 1250 and 1300ºC) in air for 5 hours. Structural and surface morphology are studied by X-ray diffraction and optical microscopy. The AC magnetic properties of these ferrites are characterized by high frequency (1 kHz-100MHz) initial complex permeability and temperature dependent permeability measurements. DC magnetizations of all samples are measured by a SQUID magnetometer. X-ray diffraction pattern show the formation of spinel crystal structure. Lattice parameters are found to decrease with substitution of Cu which can be explained with the help of ionic radii of substituted cations. The bulk density and the real part of the initial permeability, /  i , of the samples increases with increasing Cu content up to x= 0.10. Beyond this value of x, there is a decrease of both density and /  i . The bulk density and /  i of the various polycrystalline Mn0.50Zn0.50-xCuxFe2O4 increases with increasing sintering temperature up to an optimum temperature (1250oC) above that they decrease. The average grain size increases with increasing Cu content. The /  i remain fairly constant in the frequency range up to some critical frequency characterized by the onset of resonance, while at higher frequency it drops rapidly to a very small value and imaginary part ( // i  ) increase to have a peak. The Néel temperature and the saturation magnetization of various compositions show an increasing trend as a function of composition due to strengthening of the A-B interaction. A possible correlation among sintering temperature, average grain size and density is also discussed.