Investigation on structural and microwave absorption property of Co2+ and Y3+ substituted M-type Ba-Sr hexagonal ferrites prepared by a ceramic method

The Co2+ and Y3+ ions substituted M-type Ba0.5Sr0.5CoxYxFe12-2xO19 hexagonal ferrites (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were synthesized by a standard ceramic method. The phase evolution of prepared hexagonal ferrite samples was studied using X-ray diffraction technique. XRD analysis shows that compositions owe M-type as major phase and BaFe2O4 as minor phase. The absorber testing device method is adopted in order to investigate microwave absorption property of prepared ferrite compositions as a function of frequency (8.2-12.4 GHz), substitution and thickness. The microwave absorption property has been evaluated using the quarter wavelength mechanism and impedance matching mechanism. The variation in parameters measured experimentally is in agreement with put forth theoretical models. In doped compositions, the microwave absorption is found to increase with the substitution of Co2+ and Y3+ ions. Compositions x = 0.0 and 1.0 ascribe good microwave absorber characteristics with absorbed power of 96.2 and 94.7% at 11.22 and 10.04 GHz respectively. The quarter wavelength mechanism contributes for large microwave absorption in compositions x = 0.0, 0.2 and 0.8, whereas impedance matching mechanism is primarily responsible for absorption in x = 0.4, 0.6 and 1.0.