Abstract

Cobalt and copper doped Ni–Zn nano-ferrite with a composition of Ni_0.4Zn_0.4Co_0.2Cu_0.02Fe_1.98O₄ are prepared by a coprecipitation method. The structural, electromagnetic and magnetic properties are investigated by means of X-ray diffraction, impedance analyzer and vibrating sample magnetometer, respectively. Samples are calcinated at 600 °C and then subjected to different sintering temperatures. After sintering at 900 °C for 5 h, the average crystalline size is found to be 38 nm. The material shows almost constant permeability and permittivity, in the frequency range from 10 to 200 MHz, equal to 10.8 (loss tangent  0.04) and 6.5 (loss tangent  0.006), respectively. Relaxation phenomenon takes place beyond 200 MHz. The refractive index n is close to 8.3, and the reduced impedance Z/Z₀ is close to 1.3. The persistent and higher value of permeability than that of permittivity along with low losses enables this material useful for the very high frequency applications.

Research highlights

► Ni_0.4Zn_0.4Co_0.2Cu_0.02Fe_1.98O₄ nano-ferrite is prepared by a co-precipitation method. ► The average crystalline size of the nano-ferrite is 38 nm. ► The material shows almost constant μ and in the frequency range from 10 to 200 MHz. ► Relaxation phenomenon takes place above 200 MHz. ► Useful as a substrate for loading the patch antenna than pure dielectric substrates.