Impact of samarium on structural and dielectric properties of U-type hexaferrites synthesized by a sol-gel auto combustion route: Analysis of XPS, Raman and FTIR spectra

Abstract

In this work, the impact of rare earth element samarium "Sm" substitution on Ba4Co2SmxFe36-xO60 U-type hexaferrites was studied in detail. Five compositions with step size x = 0.00, 0.025, 0.050, 0.075 and 0.1 were synthesized. These five series were prepared using the sol-gel auto-combustion method and the samples were sintered for 6 h at 1250 °C. The synthesized samples were characterized by XRD, FTIR, Raman Spectroscopy, X-ray photoelectron Spectroscopy and vector network analyzer (VNA). The structure crystallography of Ba4Co2SmxFe36-xO60 was examined via XRD. The impact of Sm3+ substitution was assessed across all lattice parameters. Lattice constants 'a' and 'c' were found between 5.886 and 5.881 Å and 113.179 to 113.037 Å, respectively. FTIR was used to learn more about the crystal structure and atomic vibrations between 400 and 1000 cm−1 wave number, where higher frequency bands appear at 570 cm−1 (tetrahedral site) and the lower frequency band occurred at 424 cm−1 due to the metal-oxygen stretching vibration (Fe-O) bond at the octahedral site. Each spectrum supported a U-type hexagonal structure i.e. an investigation of the chemical and intermolecular bonds via Raman spectra. XPS confirms the presence of elements in materials. Different dielectric parameters were observed in the 1 MHz to 6 GHz range of all prepared samples. Cole-Cole graphs of prepared materials highlighted the influence of grain boundaries. A solitary semicircle in the impedance of a specific section of grain boundaries was evidenced through Cole-Cole plots. Dielectric properties strongly depend on electron hopping between Fe2+ and Fe3+ ions. The optimized parameters suggest the utility of these materials in microwave devices, multilayer chip inductors and high-frequency electrical circuit applications to reduce skin effects.