Influences of Zn Concentration on Dielectric Properties of ZnxNi1-xFe2O4 Magnetic Nanoparticles

Dielectric properties of ZnxNi1-xFe2O4 magnetic nanoparticles (MNPs) with various Zn concentration (x = 0.2-0.8) have been investigated over a wide frequency range 5–120 kHz. Zn-Ni ferrite MNPs have spinel cubic structure. The crystallite size of the sample for x = 0.2 was about 21.5 nm and then decreases by increasing Zn concentration. For sample with x = 0.4 at frequency 20 kHz, the real dielectric constant (έ) was 35.9, imaginary dielectric constant (ε ) was 20.4 and loss tangent (tan δ) was 0.6. Zn concentration would affect to availability of ferrous and ferric ions in the octahedral site which are preferentially occupied by Zn2+ ion. The dielectric constants decrease with increasing frequency. The sample with at x = 0.6 has the highest dielectric on frequency 5 kHz. The maximum AC conductivity (σAC) was 1.7 x 10^-4 Ω^-1 at 65 kHz observed for concentration x = 0.3. The dielectric constants and conductivity at low frequency are due to the existence of grains boundary while the dispersion in the high frequency region are due to the conducting grains.