Synthesis and characterization of nanocrystalline zinc substituted nickel ferrites

Li-cycling properties of nano-crystalline (Ni1 − x Zn x )Fe2O4 (0 ≤ x ≤ 1)

“…On the other hand, replacement of Ni 2+ (r i , octahedral coordination, 0.69 Å) by Fe 3+ (r i , octahedral coordination, 0.645 Å) produces only marginal decrease in the average ionic radius. The observed a values in the present study are in good agreement with those reported by Hankare et al [19] and almost obeys the Vegard's law.…”

“…2d shows the selected area electron diffraction (SAED) pattern consisting of diffuse rings and bright spots with (220) and (311) planes, indicating nano-phase nature. The particle size of NiFe 2 O 4 is found to be slightly larger than that of the other compositions due to the high energy barriers for the formations of NiFe 2 O 4 as compared with that of ZnFe 2 O 4 [19]. The crystallite sizes of (Ni 1 − x Zn x )Fe 2 O 4 are calculated by the Scherrer's equation from the Rietveld refined data, given in Table 1, and compare very well with the particle size derived from the TEM data on x00 and 1.…”

“…The variation of lattice parameter with the Zn concentration is given in Table 1 along with the Rietveld parameters. Since Zn 2+ always prefers to occupy tetrahedral site, doping of Zn 2+ in to NiFe 2 O 4 displaces equal amount of Fe 3+ from the tetrahedral site and the displaced Fe 3+ occupy the octahedral sites of Ni 2+ [19]. The cationic distribution at the tetrahedral site and octahedral site with varying x has been determined from the magnetization data by Hankare et al [19].…”

“…Since Zn 2+ always prefers to occupy tetrahedral site, doping of Zn 2+ in to NiFe 2 O 4 displaces equal amount of Fe 3+ from the tetrahedral site and the displaced Fe 3+ occupy the octahedral sites of Ni 2+ [19]. The cationic distribution at the tetrahedral site and octahedral site with varying x has been determined from the magnetization data by Hankare et al [19]. Thus, we can expect a gradual linear increase in the lattice parameter with the increase in zinc content, since the ionic radius of Zn 2+ (tetrahedral coordination, 0.60 Å) is greater than that of Fe 3+ (tetrahedral coordination, 0.49 Å) [21].…”

“…The solid solutions, (Ni 1− x Zn x ) Fe 2 O 4 (x00, 0.2, 0.4, 0.6, 0.8, 1) were prepared by citrate gel auto combustion method reported by Hankare et al [19]. Citric acid (Sigma Aldrich, 99.5%), zinc nitrate hexahydrate (Sigma Aldrich, 98%), nickel nitrate hexahydrate (Fluka, 98%), and ferric citrate hydrate (Merck, 98%) are used as starting materials.…”