Microwave absorption studies of Cr-doped Co-U type hexaferrites over 2-18 GHz frequency range

作者：Kumar Sandeep; Meena Ram Swaroop; Chatterjee Ratnamala

来源：Journal of Magnetism and Magnetic Materials, 2016, 418: 194-199.

DOI：10.1016/j.jmmm.2016.02.084

• Complex permeability
• Complex permittivity
• Ferromagnetic resonance
• Reflection loss

The effect of Cr3+ ions doping on the electromagnetic (EM) properties of polycrystalline U-type hexaferrite samples: Ba4CO2-3xCr2xFe36O60 (0.0 <= x <= 0.60, in steps of 0.15) have been studied. The X-ray diffraction (XRD) studies confirmed the formation of single U-type hexaferrite phase in all the prepared samples. Le Bail refinement of XRD patterns was used to calculate the lattice parameters 'a' and 'c'. The room temperature M-H studies indicate that the saturation magnetization (Ms) decreases and coercivity (H-c) increases with increasing Cr3+ ions concentration. The complex permittivity (epsilon*=epsilon'-i epsilon '') and permeability (mu*=mu'-i mu '') measurement were carried out using vector network analyser (VNA) over 218 GHz frequency range. The complex permeability (mu*=mu'-mu '') spectra clearly observed the ferromagnetic resonance (FMR) phenomenon in all the prepared samples. The maximum microwave absorption (MWA) of 99.97% (or minimum reflection loss R-Lmin = 34.90 dB) was observed for Ba4Co1.1Cr0.6Fe36O60 sample at 8.2 GHz frequency with 1.7 mm absorber thickness. The R-Lmin peak was found to shift towards higher microwave (MW) frequency with increase in Cr3+ ions concentration.

• 出版日期2016-11-15