Complex permittivity, permeability and wide band microwave absorbing property of La3+ substituted U-type hexaferrite

Polycrystalline samples of U-type hexaferrite series: (Ba1−3xLa2x)4Co2Fe36O60 with 0.10≤x≤0.20 in step of 0.05, are prepared by conventional solid state reaction route. Partial substitution of Ba2+ ions with La3+ ions enhances the electron hopping and reduces the magnetic interaction in the samples over the entire X-band frequencies; leading to wide band microwave absorption in all sample. Relative complex permittivity (εr=ε′−jε″) and permeability (μr=μ′−jμ″) of the prepared samples were measured using Vector Network Analyzer (VNA, Agilent PNA-L N5230A) for X-band (8.2–12.4 GHz) frequency range. The maximum absorption of 99.8% was obtained for x=0.10 sample for thickness tm=1.8 mm and all sample showed absorption ≥96%. The reflection loss (RL) calculated using the measured parameter (εr=ε′−jε″ and μr=μ′−jμ″) shows good agreement when compared with the return loss measured directly using VNA for sample x=0.20. The material can be expected to find relevance in suppression of electromagnetic interference (EMI) shielding and reduction of radar signatures.