Modifications of structural, vibrational and dielectric properties in lanthanum substituted U-type hexaferrites for microwave absorption applications

This research aims to investigate Ba 4 Zn 2 La x Fe 36-x O 60 (x = 0.00 ≤ x ≤ 0.075, Δx = 0.025) U-type hexagonal ferrites which were fabricated through sol-gel technique. A Muffle furnace was used to sinter the prepared samples for 5 h at 1200 °C. The single phase of produced samples was verified in the XRD patterns of La 3+ substituted U-type hexaferrites . Lattice parameters 'a' and 'c' values vary from 5.786-5.783 and 112.887–113.025. The crystallite size (D) measurement varied between 49 and 45 nm. The porosity (P) of the prepared samples increases, and the bulk density (ρ b ) is less than the X-ray density (ρ x ). FTIR spectroscopy showed the absorption bands range from 500 to 1100 cm −1 . Raman spectroscopy of fabricated materials revealed five different peaks: 416, 471, 531, 617, and 690. The semiconducting nature of fabricated hexagonal ferrite samples was described by UV–visible spectroscopy. All prepared samples showed different dielectric properties between 1.0 MHz and 6.0 GHz frequency ranges. Cole-Cole graphs showed the impact of grain boundaries on prepared materials. At 1.5 GHz, the minimum reflection loss was observed at −53.5 dB for sample x = 0.00. These results demonstrate that samples could be utilized in high-frequency and MW (microwave) applications with suitable cationic substitution.