Influence of Co2+ distribution and spin–orbit coupling on the resultant magnetic properties of spinel cobalt ferrite nanocrystals

Enhanced magnetic properties of doped cobalt ferrite nanoparticles by virtue of cation distribution

“…Both Rietveld refinement and Mössbauer study suggest a partially inversion for CoFe 2-x Ga x O 4 [14]. The influence of Co 2+ distribution has also been reported recently which demonstrate a change in the magnetic moment and a superparamagnetic-ferrimagnetic transition at 235 K in the cobalt ferrite nanocrystals [16].…”

Chemical bonding and magnetic properties of gadolinium (Gd) substituted cobalt ferrite

“…symmetry space group has 39 normal vibrational modes, out of which the five active Raman modes are 3T 2g +E g +A 1g [35,36]. However there are additional 12 Raman modes which are inactive include: T 1g , 2A 2u , 2E u , 4T 1u (IR),T 1g (acoustic), and 2T 2u are largely inactive in spinel structure.…”

“…This enhancement in the magnetic properties is attributed to the higher magnetic moment of Gd 3+ (4f 7 orbital) which is residing in octahedral sites is higher when compared to that of Fe 3+ (3d 5 )[36,44]. This can also be ascribed due to the migration of Co 2+ (3d 7 ) ions from the octahedral to the tetrahedral sites with a magnetic moment aligned anti-parallel to those of rare earth (RE 3+ ) ions in the spinel lattice and this increase magnetic properties is also theoretically expected[36,44]. Decrease in magnetization once Gd 3+ content is beyond x=0.1in CFGO might be attributed to compositional saturation in the CFO lattice.…”

“…Most intense T 1g (2) Raman mode at around 470 cm -1 is due to asymmetric stretching of Fe(Co)-O bonds. T 1g (2) is related to the octahedral site mode that reflects the local lattice effect in the octahedral sub-lattice and the other intense A 1g mode at about 700 cm -1 and a small peak at 620 cm -1 are the symmetry vibrations of the metal in the tetrahedral site of CoFe 2 O 4[36]. As the Gd content increases in CFO, weakening of T 1g (1) Raman mode is noted which indicates dilution of the long range order of cations in B sites[37].…”

Design of CoFe2O4/Co3O4 nanofibers with tunable morphology by Electrospinning

“…Frequencies greater than 600 cm À 1 (peak maximas at 612 and 686 cm À 1 ) are due to A 1g mode involving symmetrical stretching of the oxygen atom with respect to the metal ion in the tetrahedral void, tetrahedral breath mode (TBM). Other phonon modes at low frequencies (303 cm À 1 and 462 cm À 1 ) are caused by the metal ion in the octahedral void (E g and T 3 2g symmetries) and match with anti-symmetric and symmetric bending of the oxygen atom in M-O bond at octahedral voids [24]. However, it was difficult to detect Co 3 O 4 using Raman spectroscopy.…”