Insight of terbium substitution on the structural, spectroscopic, and dielectric characteristics of the Ba–Mg–Fe–O system

Abstract

BaMg2TbxFe16-xO27 (x = 0.00, 0.04, 0.08, 0.12 and 0.16) hexaferrites have been synthesized by sol-gel auto combustion method. The synthesized hexaferrites were characterized by structural, spectral, and dielectric properties. As the ionic radii of substituted element Tb3+(0.93 Å) is higher than Fe3+ (0.64 Å), the lattice parameter ‘a’ increase with substitution while the lattice parameter ‘c' decreases due to internal stresses and lattice distortion. Crystallite size of Tb3+ substituted W-type hexagonal ferrites are calculated and found in the range of 13.2–14.95 nm. FTIR patterns confirm the presence of Fe–O bands at octahedral and tetrahedral sites. The variations in the band positions were observed with substitutions of Tb3+ content. It is also observed that values of both force constants (Ko and Kt) increase with the inclusion of Tb3+ ions, showing the strong intermolecular bonding. The different parameters of dielectric characteristics were examined in the frequency range 1 GHz–6 GHz, and these showed variation with Tb3+ incorporation and frequency. Dielectric constant, dielectric loss factor, tan loss, and ac conductivity showed an increasing trend while Z′ and Z″ decreases with frequency because conductivity increased. Q value of these materials is low, which may be used in resonant frequency ferrites bead. The obtained results of all parameters including large value of dielectric parameters suggested that these prepared hexaferrites can be used in microwave frequency attenuating devices at GHz, recording, and storage media, and electrical components in mobile phones and refrigerator magnets.