Line width of manganese-zinc ferrite polycrystals with oxygen partial pressure

A systematic variation in line width at X band (9.78 GHz) with oxygen partial pressure was observed in Mn0.47Zn0.47Fe2.06O4 polycrystalline samples. The linewidth of the samples increased from 105 to 188 Oe with decreasing atmospheric parameters from 8.4 to 6.4. It was found that contribution of anisotropy and porosity to the linewidth was small compared to the variation in linewidth with oxygen partial pressure. Estimation of the Fe2+ concentration of samples by measuring their thermoelectric power revealed that an increase in the concentration from 1.88 to 2.44 wt % was accompanied by decreasing oxygen partial pressure. As the resistivity of grain does not vary with oxygen partial pressure, the contribution of eddy current will be the same irrespective of the oxygen partial pressure. Therefore, the systematic increase in linewidth observed in our present study was attributed to the increase in Fe2+ concentration with decreasing oxygen partial pressure. (C) 1998 American Institute of Physics. [S0021-8979(98)49011-X].