Synthesis and magnetic properties of chromium doped cobalt ferrite nanotubes

Abstract

Chromium (Cr) doped cobalt ferrite (Co1−xCrxFe2O4:x = 0.0, 0.02, 0.04, 0.06, 0.08, 0.1, denoted as to CCFO) hollow nanotubes were synthesized by electrospinnig method followed by, calcining treatment at 700 °C in air. The samples exhibited a single phase cubic spinel phase. The lattice constant of the samples was found to initially decreased and thereafter increases with increased of Cr content. The morphology analysis indicated that the samples displayed a disordered arrangements of hollow structures and the relevant surfaces were rough and porous. Transmission electron microscopy (TEM) paragraph confirmed that the doped CCFO nanotubes had a polycrystalline nature and exhibited the changes in the corresponding crystal structure. X-ray photoelectron spectroscopy (XPS) confirmed that Cr doping affect the crystal structure and atomic-binding energy. The analysis of magnetic hysteresis loop indicated an obvious reduction in the saturation magnetization (Ms) of cobalt ferrite with increasing in Cr substitution. The remanent magnetization (Mr) and coercivity were increased at first and then decreased with increasing of Cr content, which was elucidated by the surface effect and magnetic moment direction. The switching field distribution analysis indicated the magnetically crystal soft phase and there were multiple-step processes to reach magnetic reversal.

Impact of Cr Substitution on Structural, Magnetic, Electric and Impedance Study of Mn-Ni-Zn Ferrites

“…After x = 0.3, the a 0 rises with increasing Cr content. The rise in the a 0 for a higher concentration of Cr was also observed by Li et al [19] The rise in the a 0 for a higher concentration of Cr may be due to the fact that instead of trivalent the divalent Cr ion substitutes Fe 2+ in the A-site which results in the increase of lattice constant as the lattice constant of Cr 2+ is larger than that of Fe 2+ [19]. Another possible reason is: the oxides of Cr reside at the grain boundary (as seen from the micro-graphs in section 3.2) thereby obstructing the grain growth and exerts a stress on the unit cell.…”

Effects of Chromium(III) Ion Doping on Structural, Optical, and Magnetic Properties of Nickel–Cobalt Ferrite Nanoparticle

“…Table 1 shows that the lattice parameter, volume of the unit cell, and tolerance factor are decreased with increasing chromium ion, which is attributed to the ionic radii difference. This trend indicated that the prepared samples are more strained [27].…”

“…where α is the absorption coefficient, hν is the energy of the incident radiation, B is a constant known as the band tailing parameter, and E g is the energy bandgap between the top of the valence band and the bottom of the conduction band [27,31].…”

Photocatalytic Degradation Properties of Li‐Cr Ions Substituted CoFe2O4 Nanoparticles for Wastewater Treatment Application

“…[ 47 ] It is well established that Li 1+ and Cr 3+ ions have site preference for the octahedral sites, and the rest of the ions can occupy both the sites with varying ionic radii for different sites. [ 2,48 ] The lattice parameter for the composition x = 0.01 is higher than the pristine sample, which may be due to the incorporation of larger Li 1+ and Cr 3+ ions at B site replacing Fe 3+ ions.…”

“…[47] It is well established that Li 1þ and Cr 3þ ions have site preference for the octahedral sites, and the rest of the ions can occupy both the sites with varying ionic radii for different sites. [2,48] The lattice parameter for the composition x ¼ 0.01 is higher than the pristine sample, which may be due to the incorporation of larger Li 1þ and Cr 3þ ions at B site replacing Fe 3þ ions. This substitution causes increase in the concentration of Fe 3þ ions at A site, which results in the increase of mean ionic radii (r A ) of tetrahedral site and ionic radii (r B ) of octahedral site, which overall increases the lattice parameter.…”