Investigation of structural, optical and magnetic properties of Y3-xCexFe5-yEryO12 compound

Herein, we have studied the structural, optical and magnetic properties of Y 3-x Ce x Fe 5-y Er y O 12 (0.00 ≤ x ≤ 0.02), (0.00 ≤ y ≤ 0.06) compound synthesized via sol gel process. Structural characterization by X-ray diffraction (XRD) confirmed the YIG single phase formation, belong to the I a 3 ‾ d cubic centrosymmetric crystal structure. The lattice constant, lattice strain, dislocation density and average crystallite size variations were calculated and discussed in terms of the rare earth's dopant concentrations. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed redshift for the Fe–O stretching modes as the dopant content increase, testifying the crystal lattice expansion. Raman spectra inspection corroborated the YIG single phase formation and shifts in the vibrational modes confirmed the Ce 3+ and Er 3+ rare earths inclusion in the sites occupied by Y 3+ and Fe 3+ cations, respectively. The coral-like of YIG nanoparticles were confirmed by scanning (SEM) and transmission (TEM) microscopies, whereas the existence of the elements Y, Fe, O, Ce and Er, were verified by Energy Dispersive Spectroscopy analysis (EDS). The optical band gap ( E g ) decreases, while Urbach energy ( E u ) increases varying the Er content. The result confirms the effect of Ce 3+ and Er 3+ addition on the optical properties of YIG, contributing to localized oxygen vacancy defects formation. Using a phenomenological model, it was shown that, the highest probability of Er 3+ cations occupation corresponds to octahedral sites. For the Y 2.98 Ce 0.02 Fe 5-y Er y O 12 (0.00 ≤ y ≤ 0.06) compound, the theoretical saturation magnetization ( M s ) was calculated from the cation distribution obtained by the phenomenological model, resulting a slight increase with the Er content. The result agrees with the experimental M s measurements, although for y = 0.06 a discrepancy was detected, which can be attributed to the breaking of collinear array of magnetic moments due to high lattice distortions.