MICROWAVE ABSORPTIVE BEHAVIOR OF NANOCRYSTALLINE Ba3Co_(1.3)Zn_(0.3)Cu_(0.4)Fe_(24)O_(41) POWDER

摘要

In the present work, Cu~(2+) and Zn~(2+) ions were incorporated into the structure of Ba3Co2Fe_(24)O_(41), in order to obtain the Ba3Co_(1.3)Zn_(0.3)Cu_(0.4)Fe_(24)O_(41) structure, by the sol-gel precursor method in N2 inert atmosphere. The magnetization curves of Ba3Co_(1.3)Zn_(0.3)Cu_(0.4)Fe_(24)O_(41) hexaferrite nanopowders were analyzed as a function of temperature, to evaluate the superparamagnetic (SPM) behavior and its effect on the microwave absorption measurements. The permittivity (ε) and permeability (μ) values were obtained by using the transmission/reflection (T/R) method in a waveguide to evaluate the microwave absorption properties at S and X-Ku bands, for radar absorber material (RAM) application. The partial substitution of Co for Zn and Cu ions and the superparamagnetic contribution improved the ceramics' magnetic permeability, resulting in a microwave absorption greater than 90.0 % (reflectivity ≤ -10 dB) at 10.0-12.5 GHz and 13.0-16.0 GHz, with 2.5 and 2.0 mm thick, respectively.