The composition-dependent behavior of the investigated samples can be explained on the basis that Ni as well as Cu ferrites are inverse spinel in structure, and the degree of inversion depends upon the heat treatment [41, 42]. Figure 11 The variation of ε ', ε ″, tan δ, and σ ac with Zn composition at room temperature.
For the first time, a correlation between the spin-canting angle and the degree of inversion, the crystallite size and the microstrain is presented and discussed.
Also, under identical annealing conditions, sample S1 has a higher degree of inversion than S2.
Under identical annealing conditions, the nanocrystalline samples synthesised by the citrate method show high degree of inversion.
Delta represents the degree of inversion (defined as the fraction of tetrahedral site occupied by Fe3+ cations) which depends on the synthesis method and thermal treatment.
The estimated cation distribution and degree of inversion from the Rietveld analysis for samples S1 and S2 are enlisted in Table 5.
The degree of inversion [2] (defined as the fraction of tetrahedral sites (A sites) occupied by Fe3+ ions) of both samples S1 and S2 increases with the annealing temperature.
The degree of inversion varies between species, with humans and rats subject to less inversion than that seen in mice; this enantiomerization is an enzymatic process proceeding through an acyl coenzyme A thioester intermediate.
However, a normal foot cannot adopt a true club-foot position because even in the extreme degrees of plantar flexion and inversion, the fore part of the foot moves with the hind part, and a cavus deformity does not develop since there is no discrepancy in the degree of inversion of the front and back part of the foot.
For NiAl2O4 the degree of inversion depends on the value of u. Figure 16b shows that if the crystal is a normal spinel u would be around 0.265 since this gives a bond valence sum of 2 around tetrahedral Ni2+ and 3 around octahedral Al3+, but if it is an inverse spinel u would be 0.253 with a bond valence sum of 3 around tetrahedral Al3+ and 2.5 around the mixed octahedral site.
