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.
