CRYSTAL, MAGNETIC AND ELECTRIC BEHAVIOR OF COMNXFE2-XO4 CUBIC FERRITES

Six powder samples of CoMnxFe2-xO4 (O less-than-or-equal-to x less-than-or-equal-to 1) were synthesized by using a ceramic sintering technique. X-ray powder diffraction patterns were obtained and confirmed the presence of single-phase spinel structure with no evidence of impurities. Lattice constants were determined. Differential thermal analysis measurements showed no variation in crystal phase with temperature. AC conductivity measurements at the temperature range (300-950 K) and for the frequency range (10(2)-10(5) Hz) were also carried out and the Neel transition temperatures for all samples were determined. Mossbauer effect patterns revealed magnetic ordering for all compositions at room temperature. The obtained spectra were successfully analysed into two Zeeman sextets, could be attributed to the tetrahedral and octahedral sites. The different Mossbauer effect parameters were deduced and discussed. Neutron diffraction measurements were also performed where oxygen parameters and cation distributions were determined, and magnetic structure were studied. All obtained results from the different techniques support the Neel model of ferrimagnetism for such compounds.