Electromagnetic and microwave absorbing properties of NiCoZn-ferrites doped with La3+

NiCoZn-ferrites doped with La3+ ions, Ni0.35Cu0.15Zn0.5LaxFe2O4(x=0, 0.02, 0.04, 0.06), were prepared by sot-gel method. The effect of the La3+ ions doping on the microstructure, complex permeability, permittivity and microwave absorption of the samples was investigated. The results show that all samples exhibited a well defined spinet phase when x <= 004 with the sintering temperature of 1000 degrees C. With the increase of the substitution ratio of La3+ ions from 0 to 0.06, the lattice parameters increased gradually, which resulted in the change of the particle shape and size. The data of magnetism showed that the addition of La3+ ions result in the decrease of saturation magnetization (M-s) and coercivity (H-c). The La3+ ions doped in the ferrite not only improved complex permittivity, but also microwave absorbency. The minimum reflection loss of -34 dB was obtained for x=0.02 sample for thickness t=4 mm and its bandwidth under -10 dB reaches 5.5 GHz. (C) 2013 Elsevier B.V. All rights reserved