Contribution to Analysis of Co/Cu Substituted Ni-Zn Ferrites

Abstract

In this communication, Co/Cu substituted Ni-Zn ferrites processed through sol-gel synthesis using polyethylene glycol (PEG) as a chelating agent are studied, intending to aid in understanding and choosing the optimum ferrite material for high frequency applications. Lattice constant and average crystallite size have been estimated from FWHM of the X-ray diffraction peaks, and these parameters are understood by considering the ionic radii of the substituted as well as the replacing ions. Observed variations in saturation magnetization and initial permeability for these ferrites have been explained on the basis of anisotropy contribution for cobalt and segregation of copper at grain boundaries evident from scanning electron micrographs.

Enhancement in magnetic permeability of Ni‐Co‐Zn ferrites using CuO doping for RF and microwave devices

“…It is well known that lattice expands or shrinks depending upon the radius of the doped ions (Cu 2+ ). 24,25,26 Our observations are consistent with the reported prior works that shows an increase in the lattice constant at lower concentrations, inferring the substitution of Cu 2+ ions to both Ni 2+ and Co 2+ ions in the structure. 25 As the amount of copper ions increase in the composition, there was a slight decrease in lattice constant after x > 3 wt%, which may be attributed to segregation of excess copper ions at the grain boundaries.…”

“…24,25,26 Our observations are consistent with the reported prior works that shows an increase in the lattice constant at lower concentrations, inferring the substitution of Cu 2+ ions to both Ni 2+ and Co 2+ ions in the structure. 25 As the amount of copper ions increase in the composition, there was a slight decrease in lattice constant after x > 3 wt%, which may be attributed to segregation of excess copper ions at the grain boundaries. 27,28 Also, there is a possibility of migration of copper ions to the A site rather than the B site due to excess amount of copper ions.…”

“…This can be attributed to difference in ionic radii of Copper (0.73 Å), Nickel (0.69 Å), and Cobalt (0.745 Å) ions. 25 This initial variation in lattice constant can be attributed to the fact that, Cu 2+ ions are known to have tendency to replace both Ni 2+ and Co 2+ ions since they both reside at octahedral B site in the structure. 12 Based on their ionic radii Cu 2+ (0.73 Å), Ni 2+ (0.72 Å), and Co 2+ (0.74 Å), it has been observed that at lower CuO doping level, Cu 2+ would replace both Ni 2+ and Co 2+ ions without any specific preference that leads to variations in the lattice constant, depending on which ion Cu 2+ replaces.…”

Impedance and Dielectric Analysis of Nickel Ferrites: Revealing the Role of the Constant Phase Element and Yttrium Doping

“…Thanks to their high electrical resistivity and electrochemical stability, catalytic and magnetic behavior, the nickel ferrites found their use in photoelectric devices, catalysis, sensors and nano-devices [9,10]. Some of these properties can be further improved by the replacement of Ni 2+ ions with divalent cations, or with the substitution of Fe 3+ with trivalent cations [11][12][13][14][15][16].…”

Structural aspects and magnetic properties of Nd3+ doped nickel-zinc ferrites

“…Doping of metal ions could change the cation occupancy, thus altering porosity, bond angles, bondlength, particle size [15] and superexchange interactions. Copper substitution in place of nickel improves densification [16], magnesium doping results in substantial changes in grain size, permeability, resistivity and loss factor [17]. Cobalt substitution was observed to lower coercivity [18], improve permeability [19] and frequency stability of permeability at higher frequencies.…”