Structure, ac conductivity and complex impedance study of Co₃O₄ and Fe₃O₄ mixed spinel ferrites

Abstract

We have synthesized the composition of Fe 3(1-x) Co 3x O 4 (x =0.1, 0.3 and 0.5) spinel ferrite using the techniques of mechanical alloying, high temperature annealing of milled samples and conventional solid state sintering. We present here comparative results of the crystal structure formation and dielectric properties of the materials studied at room temperature. The crystalline structure of the single phased samples is cubic spinel phase with space group Fd3m. The alloying of two spinel oxides (i.e., Fe 3 O 4 and Fe 3 O 4) is also complemented from FTIR spectrum. Impedance spectroscopy suggested only one semi circle in the Cole-Cole plot of mechanical milled samples, which indicated the dominant grain boundary contribution in the conduction mechanism. In addition to the grain boundary contribution, the electrical conduction from grains is also substantial in the single phased compositions of the present material. The present results could be interesting in tailoring the electrical conductivity in magnetic nanocomposite.

Alloying of Fe3O4 and Co3O4 to develop Co3xFe3(1−x)O4 ferrite with high magnetic squareness, tunable ferromagnetic parameters, and exchange bias

“…This is due to doping effects of Co ions in Fe 3 [24,26]. This structural transformation from inverse spinel (for low Co content) to normal spinel (for high Co content) is consistent to the results of Mössbauer spectroscopy [24] and FTIR spectroscopy [19]. Room temperature magnetic properties in low field regime (field up to ±16 kOe) were studied using VSM (Lakeshore 7404, USA).…”

“…In previous report [19], we have demonstrated the structural and dielectric properties of Co 3x Fe 3(1Àx) O 4 with three specific Co content (x = 0.1, 0.3, 0.5). This ferrite composition was prepared by alloying of magnetite (Fe 3 O 4 ) and cobaltite (Co 3 O 4 ).…”

Dielectric and transport properties of Zn-substituted cobalt ferrites

“…The sharp peaks reveal that the samples are in good crystalline form. One peak between (222) and (440) has been observed which is due to the charge valence of the cobalt compounds (Co 2+ and Co 3+ in Co 3 O 4 ) which is not neutralized and a fraction of Fe atoms is coming out of the spinel lattices to form the additional phase (Bhowmik et al 2010). (1) lattice parameters (a) were determined.…”

Rietveld analysis of XRD patterns of different sizes of nanocrystalline cobalt ferrite

“…The higher frequency absorption band (ν 1 ) lies in the range 500 to 600 cm −1 and is assigned to vibration of the tetrahedral metal complex which consists of a bond between the oxygen ion and the tetrahedral site metal ion (O-M Tet ), and the lower frequency absorption band (ν 2 ) lies in the range of 400 to 490 cm −1 and is assigned to vibration of the octahedral metal complex which consists of a bond between the oxygen ion and the octahedral site metal ion (O-M Oct ) [36]. The appearance of higher frequency band is due to the stretching vibration, while the lower frequency band is due to the bending vibration [37]. These band positions are found to be in agreement with the characteristic infrared absorption bands of cobalt ferrite nanocrystals [38].…”