Impacts of Sol-Gel Auto-Combustion and Ultrasonication Approaches on Structural, Magnetic, and Optical Properties of Sm-Tm co-Substituted Sr0.5Ba0.5Fe12O19 Nanohexaferrites: Comparative study

Yassine Slimani; Munirah Abdullah Almessiere; Sadik Güner; Umran Kurtan; Abdulhadi Baykal

doi:10.3390/nano10020272

Impacts of Sol-Gel Auto-Combustion and Ultrasonication Approaches on Structural, Magnetic, and Optical Properties of Sm-Tm co-Substituted Sr_0.5Ba_0.5Fe₁₂O₁₉ Nanohexaferrites: Comparative study

Nanomaterials (Basel). 2020 Feb 6;10(2):272. doi: 10.3390/nano10020272.

Authors

Yassine Slimani¹, Munirah Abdullah Almessiere¹, Sadik Güner², Umran Kurtan³, Abdulhadi Baykal⁴

Affiliations

¹ Department of Biophysics, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia.
² Institute of Inorganic Chemistry, RWTH Aachen University, D-52074 Aachen, Germany.
³ Department of Materials and Materials Processing Technologies, Vocational School of Technical Sciences, İstanbul University-Cerrahpaşa, İstanbul 34500, Turkey.
⁴ Department of Nanomedicine, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441, Saudi Arabia.

Abstract

In this paper, we introduced a comparative study of Sm-Tm-substituted Sr-Ba nanohexaferrites (NHFs), Sr_0.5Ba_0.5Tm_xSm_xFe_12-2xO₁₉ with x = 0.00-0.05, manufactured via both citrate sol-gel auto-combustion and ultrasonication approaches. The phase formation of M-type hexaferrite (HF) for both compositions was confirmed by X-ray diffraction (XRD) powder pattern, Fourier-transform infrared (FT-IR) spectra, scanning and transmission electron microscopy (SEM and TEM) micrographs, energy dispersive X-ray (EDX) spectra, and elemental mappings. The magnetic properties at room temperature (RT) and low temperature (T = 10 K) were also investigated. M-H loops revealed ferrimagnetic nature for various prepared nanohexaferrites via sol-gel and ultrasonication routes. The M_s (saturation magnetization) and M_r (remanence) values increased with increasing Tm-Sm substituting contents. M_s and M_r reached their maximum values at x = 0.04 in the case of samples prepared using the sol-gel technique and at x = 0.03 for those prepared via ultrasonication route. M-H loops were very broad in samples prepared via ultrasonication route in comparison to those produced by means of the sol-gel approach, implying that the products synthesized via ultrasonication route have greater values of coercivity (H_c). The variations in H_c values with respect to Tm-Sm substitutions were governed by the evolutions in the magneto-crystalline anisotropy. Diffuse reflectance spectra (DRS) were employed to estimate the direct band gap of pristine and co-substituted Sr_0.5Ba_0.5Fe₁₂O₁₉ hexaferrites. Optical energy band gaps (E_g) of pristine samples were significantly tuned by co-substitution of Tm³⁺ and Sm³⁺ ions. E_g values of the Sr_0.5Ba_0.5Fe₁₂O₁₉ sample, which was synthesized using the sol-gel method, decreased almost linearly from 1.75 to 1.45 eV by increasing co-doped ion content. However, we observed a sharp drop from 1.85 eV to an average of 1.50 eV for the samples, which were synthesized using the ultrasonication approach.

Keywords: hexaferrite; magnetic properties; morphology; optical properties; rare earths; structure.