Structural and magnetic properties of CaMg₂Fe₁₆O₂₇

Abstract

A new compound, CaMg₂Fe₁₆O₂₇, is synthesized for the first time, in polycrystalline form, using stoichiometric mixture of oxides with standard ceramic technique and characterized by X-ray diffraction. It is found to have a hexagonal W-type structure with lattice parametersa = 5.850 Å andc = 33.156 Å. Electrical studies show that the compound is a semiconductor with energy of activation, ΔE = 0.56 eV. Electrical conductivity results show a transition in the conductivity vs temperature plot near the Curie temperature. The activation energy value obtained for the paramagnetic phase is found to be higher than that of the ferrimagnetic phase. The molar magnetic susceptibility was measured in the temperature range 300–850 K and the results show that the compound is ferrimagnetic at room temperature. The compound also shows hysteresis at 300 K. Paramagnetic nature of the sample above Curie temperature is also studied. The Curie molar constantC _M bdcalculated from the plot of 1/χ_M vsT(K) bdis found to be nearly in agreement with the expected value.