Microstructural, magnetic, and hyperfine characterizations of Cu‐doped cobalt ferrite nanoparticles

Abstract

We have investigated the structural and magnetic properties of polycrystalline Cu‐substituted cobalt ferrite (CuxCo1−xFe2O4: x = 0.00, 0.15, 0.30, 0.45, 0.60) nanoparticles, synthesized via chemical coprecipitation method. The prepared samples were of single phase as confirmed by X‐ray diffraction analysis. The mean crystallite size ranged from 44 to 65 nm was obtained using Scherrer's formula. M‐T curves revealed that the Curie temperature of all the samples was above room temperature and it was found to decrease with increasing Cu concentration, which was supported by Mössbauer spectra. Field cooled (FC) hysteresis curves showed ferrimagnetic nature at 5 K and room temperature. It was observed that careful variation of Cu concentration in cobalt ferrite lead to weak A‐B interaction with tunable magnetic properties.

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“…Broadening of diffraction peaks is mainly due to three primary reasons i.e. crystallite size effect, microstrain and instrumental effect [24,25]. Elimination of instrumental broadening was done by recording the diffraction pattern of bulk LaB 6 powder.…”

“…Elimination of instrumental broadening was done by recording the diffraction pattern of bulk LaB 6 powder. After removing the instrumental broadening, the total line width ( ) takes the form as [25] = + (2)…”

“…where is full-width half maxima, represents the geometrical factor (0.9 for spherical shaped particles), signifies wavelength of Cu K α line (= 1.5406 Å), D corresponds to the mean crystallite size, addresses microstrain and θ is the Bragg's angle respectively. Rearranging the equation 3, we get the known form as shown below [25] cos = 0.9 cos + 4 sin (4)…”

“…Separation of size and microstrain effects from total line width of diffracted peaks was done by plotting cos as a function of 4 sin which is familiar as the Williamson-Hall (W-H) graph as described in equation (4). The slope of this curve represents microstrain present inside the crystal and crystallite size was calculated from intercept on cos axis [24,25]. W-H plot of all the samples is presented in figure 2.…”

“…Elimination of instrumental broadening was done by recording the diffraction pattern of bulk LaB 6 powder. After removing the instrumental broadening, the total line width ( ) takes the form as[25] Separation of size and microstrain effects from total line width of diffracted peaks was done by plotting cos as a function of 4 sin which is familiar as the Williamson-Hall (W-H) graph as described in equation(4). The slope of this curve represents microstrain present inside the crystal and crystallite size was calculated from intercept on cos axis[24,25].…”