IS THE IRREGULAR DISTRIBUTION OF Zn IONS CONFINED TO CO-PRECIPITATED ZINC FERRITE ONLY?-STRUCTURE ANALYSIS OF Mn-Zn FERRITE USING EXAFS-

摘要

Ferrites have found wide use in many industrial applications and can be prepared either by ceramic or co-precipitation technique depending on their end use. But, it has been found that the ferrite of similar composition differ in their magnetic property depending on the preparation technique and particle size. One of the reason for such deviation is believed due to the difference in particle size and the presence of magnetic inactive layer around the particle[1]. The weight percent of such layer decreases with increasing particle size and causes an increase in magnetization. In the ferrite the non-magnetic zinc ions are added to maximize the net magnetic moment in the structure and are believed to occupy the tetrahedral sites. In the recent past there have been considerable research on co-precipitated zinc ferrite[2] which showed anomalous magnetic behavior compared with the one produced by ceramic method. This could not be explained by the presence of magnetic inactive layer since the magnetization reduced with the increase in particle size. Structure analysis by EXAFS suggested that the irregular distribution of Zn ion in co-precipitated zinc ferrite caused the anomalous magnetic behavior[3]. From the magnetic material research point of view, it is interesting to know whether this irregular distribution of zinc ion is something confined to zinc ferrite only or common to co-precipitated ferrite that has zinc ion in it. In this paper, we discuss the metal ion distribution in co-precipitated ultra fine Mn-Zn ferrite (MnO:ZnO:Fe_(2)O_(3)=0.41:0.18:0.41) that has found application in temperature sensitive magnetic fluid, Mn-Zn ferrite with different proportions of Mn and Zn and also Mn-Zn ferrite of various particle diameter by the extended absorption fine structure. (EXAFS).