Complex permittivity, permeability and microwave absorbing properties of (Mn 2− xZn x)U-type hexaferrite

Abstract

Complex permittivity, permeability and microwave absorbing properties of a U-type hexaferrite series Ba 4Mn (2− x) Zn x Fe 36O 60 (with 0≤ x≤2 in step of 0.5) have been examined in the X-band (8.2–12.4 GHz) frequency range. The series have been prepared using conventional solid state reaction route. Microstructural variations with composition have been found with X-ray diffraction (XRD) and scanning electron microgram (SEM). The complex permittivity ( ε ⁎= ε′− jε″) and permeability (μ ⁎= μ′ −jμ″) were measured using vector network analyzer (Agilient Make model PNA E8364B). These parameters were then used for calculating the reflection loss for determination of microwave absorbing properties. Addition of Zn resulted in an increase in reflection loss from −4 dB (or 60 % absorption) in sample with x= 0 to −32 dB (99.92% absorption) in sample with x=1 when the sample thickness was 1.7 mm. Multiple peaks of resonance were obtained in the dielectric and magnetic loss spectra for all samples with x>0. The result indicates that the sample with composition Ba 4MnZnFe 36O 60, i.e., x=1, can be used effectively for microwave absorption and suppression of electromagnetic interference.