Shielding properties of CuNiZn ferrite in the radio frequency range

M. S. RUIZ; P. G. BERCOFF; S. E. JACOBO

CERAMICS INTERNATIONAL

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2013 vol. 39 p. 4777 - 4782

0272-8842

Shielding properties of copper-doped NiZn ferrites in the frequency range 1 MHz?1.8 GHz, were explored. Samples of composition CuxNi(0.4-x)Zn0.6Fe2O4 with x=0.0; 0.1; 0.2; 0.3; 0.4, were prepared by the ceramic method. Powders and pellets were sintered at 1100oC for 2 h. The effect of compositional variation on structural, dielectric and magnetic properties was investigated. X-ray diffraction measurements confirmed the formation of single-phase cubic spinel structure at the selected sintering temperature. The addition of copper promotes grain growth, increases samples density and modifies saturation magnetization, permeability and permittivity in the frequency range from 1MHz to 1.8GHz. The electric resistivity decreases with Cu substitution. Microwave absorption, in the explored frequency range is strongly dependent on the amount of Cu in the ferrite. As the RL values for all the samples are above 35 dB, they can all be considered as shielding materials. The optimum attenuation occurs for x=0.2, reaching a minimum reflection loss of almost 60 dB at 10 MHz and presenting an attenuation bandwidth of at least 3 MHz.