Preparation and Characterization of Manganese Ferrite Aluminates

Abstract

Recommended by R. N. P. ChoudharyAluminum doped manganese ferrites MnAl x Fe 2−x O 4 with 0.0 ≤ x ≤ 1.0 have been prepared by the double ceramic route. The formation of mixed spinel phase has been confirmed by X-ray diffraction analysis. The unit cell parameter 'a O ' is found to decrease linearly with aluminum concentration due to smaller ionic radius of aluminum. The cation distributions were estimated from Xray diffraction intensities of various planes. The theoretical lattice parameter, X-ray density, oxygen positional parameter, ionic radii, jump length, and bonds and edges lengths of the tetrahedral (A) and octahedral (B) sites were determined. 57 Fe Mössbauer spectra recorded at room temperature were fitted with two sextets corresponding to Fe 3+ ions at A-and B-sites. In the present ferrite system, the area ratio of Fe 3+ ions at the A-and B-sites determined from the spectral analysis of Mössbauer spectra gives evidence that Al 3+ ions replace iron ions at B-sites. This change in the site preference reflects an abrupt change in magnetic hyperfine fields at A-and B-sites as aluminum concentration increases, which has been explained on the basis of supertransferred hyperfine field. On the basis of estimated cation distribution, it is concluded that aluminum doped manganese ferrites exhibit a 55% normal spinel structure.

Influence of annealing temperature on structural and magnetic properties of MnFe2O4 nanoparticles

“…The XRD measurements show that all peaks of MnFe 2 O 4 nanocrystallite are consistent with those of standard pattern of manganese ferrite [9]. …”

Effect of Terbium Ion Substitution in Inverse Spinel Nickel Ferrite: Structural and Magnetic Study

“…where u is the oxygen parameter (u = 0.3811 for NiFe2O4) [29]. Additionally, the distances LA and LB between the magnetic ions at the A-sites and B-sites (the jump length or hopping length), respectively, can be obtained where LA = a√3/4, and LB = a√2/4 [30]. Table 2 lists the calculated The interionic distances (i.e., cation-anion distances at the A-site (d AL ) and B-site (d BL ), together with the distance of the closest anion-anion approach, tetrahedral edge, d AE , and shared and unshared octahedral edges, d BE , d BEU ) are calculated according to the following equations [27,28],…”

“…where u is the oxygen parameter (u = 0.3811 for NiFe 2 O 4 ) [29]. Additionally, the distances L A and L B between the magnetic ions at the A-sites and B-sites (the jump length or hopping length), respectively, can be obtained where L A = a √ 3/4, and L B = a √ 2/4 [30]. Table 2 lists the calculated parameters.…”

Cation distribution in nanocrystalline Al3+ and Cr3+ co-substituted CoFe2O4

“…Using the values of 'a', the radius of oxygen ion R 0 = 1.32Á and r A in the following expression, the value of the oxygen positional parameter 'u' can be calculated using the following relation [13] …”