Smart magnetodielectric nano-materials for the very high frequency applications

Cobalt and copper doped Ni–Zn nano-ferrite with a composition of Ni0.4Zn0.4Co0.2Cu0.02Fe1.98O4 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
► Ni0.4Zn0.4Co0.2Cu0.02Fe1.98O4 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 ɛ 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.