Microwave absorption studies of Ca-NiTi hexaferrite composites in X-band

The effect of Ni2+Ti4+ substitution On complex permeability, permittivity a nd microwave absorption has been studied for [Ca(NiTi)(x)Fe12-2xO19](96.0)[ La2O3](4.0) ferrite-polymer composites, wherein x varies from 0.0 to 1.0 in steps of 0.2, in frequency range from 8.0 to 12.4 GHz. The ferrite-composi tes with x > 0.0 exhibit significant dispersion in complex permittivity (ep silon'-j epsilon ") with maximum value of epsilon " observed for x = 0.6. T he dispersion in complex permeability (mu'-j mu ") is not significant and i s attributed to the shielding effect of polymer matrix over the ferrite cry stallites. The variation of reflection loss has been studied as a function of frequency (f), Ni2+Ti4+ content (x) and thickness of the absorber. A min imum reflection loss of - 30.0 dB is obtained for composite with x = 0.4 an d an absorber thickness of 4.15 mm. The experimental values of the matching frequency and the matching thickness agree well with the theoretical value s obtained by solving the equations numerically. (C) 2000 Elsevier Science S.A. All rights reserved.