Abstract
The present study investigates the influence of La3+ and Pr3+ doping on the structural, magnetic properties, and hyperfine fields of Sr0.7RE0.3Fe12-2x CoxAlxO19, (RE: La3+ and Pr3+, x = 0.0 - 0.8) hexaferrite compounds prepared via auto-combustion technique. The XRD analysis shows a linear decrease in a and c lattice and unit cell volume contraction with the content x. The room temperature magnetic study shows that for the Pr3+ doped Sr0.7Pr0.3Fe12-2x CoxAlxO19 (Pr3+-SrM), the magnetization value monotonically decreases while for La3+ doped Sr0.7La0.3Fe12-2xCoxAlxO19 (La3+-SrM) magnetization value shows a noticeable increase in magnetization value with x. The coercivity of the Pr3+-SrM compound was observed to decrease while that of the La3+-SrM compound showed a marked 40% increase at x = 0.2 (~5829 Oe) in comparison to undoped SrFe12O19 (~3918 Oe). A difference in Curie temperature was also observed, with Tc ~ 525°C at x = 0.4 for Pr3+-SrM and Tc = 505°C for x = 0.4 for La3+-SrM compound. The observed differences in magnetic properties have been explained on the basis of the site occupancy of Co2+ and Al3+ in the presence of rare-earth ions. The presence of non-magnetic rare-earth ion, La3+, improved saturation magnetization, and coercivity and deemed suitable replacement for Sr2+. The hyperfine parameters namely quadrupole shift showed a decrease with the La3+ or Pr3+ doping independent of (Co2+-Al3+) ions doping. Overall, the Mossbauer analysis suggests that the (Co2+-Al3+) impurities prefer occupancy at 2a site.
Highlights
The M-type hexaferrite, Strontium hexaferrite, is an excellent candidate for technological applications because of its high uniaxial magneto-crystalline anisotropy, large magnetization, high permeability, low conductive losses, excellent chemical stability, corrosion resistance and excellent high-frequency response [1] [2] [3]
The present study investigates the influence of La3+ and Pr3+ doping on the structural, magnetic properties, and hyperfine fields of Sr0.7RE0.3Fe12−2x CoxAlxO19, (RE: La3+ and Pr3+, x = 0.0 - 0.8) hexaferrite compounds prepared via auto-combustion technique
The popularity of strontium hexaferrite is due to its economic success, which is its low price per unit available magnetic energy and its wide availability
Summary
The M-type hexaferrite, Strontium hexaferrite, is an excellent candidate for technological applications because of its high uniaxial magneto-crystalline anisotropy, large magnetization, high permeability, low conductive losses, excellent chemical stability, corrosion resistance and excellent high-frequency response [1] [2] [3]. Lechevallier et al reported that the only light rare-earth enters the structure, which a solubility that is related to the shape of the charge distribution of the 4f electrons to its surroundings in the crystal structure Only those rare-earth ions have easy accommodation at the Sr2+ site, whose surroundings favor an oblate electronic distribution. In the absence of Co2+, one of the Fe3+ has to convert to Fe2+, which has a deleterious effect on the magnetization With this strategy in mind, the present study investigates, the influence of the 1) rare-earth substitution, Pr3+, and La3+, at the Sr2+ site and 2) Co2+-Al3+ substitution at Fe3+ sites on the overall magnetic properties of the Sr0.7RE0.3Fe12−2xCoxAlxO19 compound
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