Microwave absorbing properties of rare-earth elements substituted W-type barium ferrite

W-type barium ferrites Ba(MnZn)(0.3)Co1.4R0.01Fe15.99O27 with R = Dy, Nd and Pr were prepared by chemical coprecipitation method. Effects of rare-earth elements (RE) substitution on microstructural and electromagnetic properties were analyzed. The results show that a small amount of RE 31 ions can replace Fe3+ ions and adjust hyperfine parameters. An obvious increase in natural resonance frequency and high frequency relaxation, and a sharp decrease for complex permittivity have been observed. Furthermore, the matching thickness and the reflection loss (RL) of one-layer ferrite absorber were calculated. It reveals that thin and broad-band can be obtained by RE-substitution. But only when the magnetic moment of RE3+ is higher than that of Fe3+, can substitution be effective for higher RL. Dy-substituted ferrite composite has excellent microwave absorption properties. The frequency (with respect to -10 dB RL) begins from 9.9 GHz, and the bandwidth reaches far more than 8.16 GHz. The peak value is - 51.92 dB at a matching thickness of 2.1 mm. (c) 2006 Elsevier B.V. All rights reserved.