Structural and temperature dependent dielectric behavior of Cr and Zn doped MnFe2O4 nano ferrites

The Mn0.5Zn0.5Fe2O4 and Mn0.5Cr0.5Fe2O4 ferrites were synthesized by low temperature sol gel auto combustion method. The laboratory and Synchrotron x-ray diffraction confirms the formation of face centered cubic structure with Fd-3m space group. Particle sizes as calculated from Synchrotron (laboratory) source discern decreasing value 14.85 (15.17) nm in Mn0.5Zn0.5Fe2O4 ferrites, however an enhanced particle size of 27.67 (19.88) nm is seen for Mn0.5Cr0.5Fe2O4. The dielectric constant (dielectric loss) is 400 (7.88) for Mn0.5Zn0.5Fe2O4 and 1.1 × 104 (0.6) for Mn0.5Cr0.5Fe2O4 ferrites at 300 K and at 100 Hz and found to have increasing value with temperature and frequency. The increase in the value of ac conductivity is also observed with the increase in temperature and frequency. The activation energy for Mn0.5Zn0.5Fe2O4 (Mn0.5Cr0.5Fe2O4) ferrite is 0.42 (0.44) eV at 100 Hz and 0.22 (0.23) eV at 1 MHz, respectively. These observations indicate that Cr doping is more useful in device application as compared to Zn in MnFe2O4.