Structural and dielectric properties of Sr4Zn2Fe36O60 U-type hexaferrites with optimized Gd contents and sintered by a two-step process

Abstract

The structural and dielectric properties of Gadolinium substituted U-type hexaferrites (Sr4Zn2Fe36O60) were investigated. The samples were synthesized via the Sol-gel auto combustion route. In a muffle furnace, these samples were sintered for 5 h at 1250 °C. The pellets of synthesized powder samples were characterized by XRD, PL, Dielectric, FTIR, and Raman spectroscopies. Structural elucidation of Sr4Zn2Fe36-xGdxO60 was done via XRD. The obtained XRD patterns were matched with the prior literature. The impact of Gd3+ substitutions was measured on all the lattice parameters. Lattice constants “a" and “c" were found between 5.871 and 5.900 Å and 111.76–112.23 Å, respectively. The PL spectra of Sr4Zn2Fe36-xGdxO60 demonstrated multiple emissions in the range of 630 nm–700 nm, and by analyzing PL spectroscopic results, a bandgap of 1.8742 eV was found for the un-doped sample. Many dielectric parameters, i.e., Dielectric constant (ε'), Dielectric losses (ε''), Loss tangents (tanδ), Complex electric modulus (M' & M″), and A.C conductivity (σac) were investigated at room temperature by changing the frequencies from 1 GHz to 6 GHz. The varying trends of dielectric parameters were analyzed with the assistance of the Maxwell-Wagner model. Various absorption bands were observed in the range of 500–4000 cm−1 by plotting the FTIR spectroscopic results of Sr4Zn2Fe36-xGdxO60. Raman spectra demonstrated a combination of strong and fragile peaks in 1–1800 cm−1. The obtained results of various spectroscopies suggested that the prepared materials can be used extensively for different Micro-Wave attenuation purposes.