Complex permittivity, permeability and microwave absorbing studies of (Co 2− x Mn x ) U-type hexaferrite for X-band (8.2–12.4 GHz) frequencies

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2010-07, Vol.171 (1), p.133-138
• Main Authors: Meena, R.S., Bhattachrya, Sudeshna, Chatterjee, Ratnamala
• Format: Article
• Language: English
• Subjects: Absorbing; Absorption; Complex permeability; Complex permittivity; Dielectric loss; Frequency ranges; Magnetic permeability; Manganese; Microwave absorption; Microwaves; Permeability; U-type hexaferrite; X-band
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2010.03.086

In order to develop a new microwave absorbing material over the X-band (8.2–12.4 GHz) frequency range, polycrystalline samples of U-type hexaferrite series: Ba 4Co 2− x Mn x Fe 36O 60, with x varying from 0 to 2.0 in steps of 0.5, were prepared through conventional solid state reaction route. X-ray diffraction analysis was done to find the structural change with composition. The variation of electromagnetic parameters (complex permittivity ɛ* = ɛ′ − jɛ′′ and complex permeability μ* = μ′ − jμ′′) and microwave absorbing properties were studied over the X-band frequency range with varying composition. Both dielectric loss ( ɛ′′) and magnetic loss ( μ′′) were found to decrease with increasing x, whereas the dielectric constant ( ɛ′) and magnetic permeability ( μ′) variations are reciprocal with Mn addition. Composition with x = 1, presenting a maximum value of microwave absorption of 99.84% (or reflection loss R L = −28.4 dB) at 8.45 GHz when sample thickness is 1.7 mm. This composition also offered wide band absorption (>96%) throughout the X-band frequencies where it can be used for suppressing electromagnetic interference and radar signature.