Influence of varying particle sizes on microwave absorbing properties of U-type hexaferrites and development of broadband microwave absorber

The present study investigates the influence of particle size variation on the microwave (MW) absorbing properties of (Ba0.7Bi0.3)(4)Co2Fe34.8Zn1.2O60 U-type hexaferrites. The hexaferrite powders of varying particle sizes were prepared through heating at a constant optimized temperature for different holding time (4, 6, 8 and 10 h) using a novel one-pot chemical route. With an increase of the holding time (4 to 10 h), the average particle size is found to increase monotonically (similar to 65 to similar to 170 nm). The hexaferrite sample prepared at a holding time of 8 h exhibits an excellent reflection loss (R-L) of 44.2 dB (99.99% MW absorption) at 11.6 GHz frequency. In addition, a broadband MW absorber has been developed through an ingenious blending of equal amounts of all four hexaferrite powders. The mixed U-type hexaferrite displays an excellent bandwidth of similar to 8.4 GHz for 90% or more MW absorption. The reflection losses (S-11) are also measured experimentally through one port short-circuited transmission line method using vector network analyzer (VNA). The strong and broadband absorption results suggest that the prepared U-type samples can be utilized in the high-performance MW absorbing applications.

Automated summary

This study investigates the influence of particle size variation on the microwave absorbing properties of U-type hexaferrites. Results show that increasing holding time leads to larger particle sizes and improved microwave absorption properties. By blending different particle sizes of hexaferrite powders, a broadband microwave absorber with excellent absorption performance has been developed.