Tailoring ZnO/CoFe<sub>2</sub>O<sub>4</sub> nanocomposites: structure, optical, dielectric and magnetic study
Manal A. Mahdy, A. A. Azab, I.K. El Zawawi, Gamal Turky
Abstract
Abstract The structural, morphology, optical, magnetic and dielectric properties of the (ZnO) 1–x (CoFe 2 O 4 ) x , (x = 1, 3 and 5 wt%) nanocomposites synthetized by sonomechanical method were investigated using XRD, FE-SEM, HR-TEM, UV-visible, VSM and BDS. XRD analysis shows that, ZnO and CoFe 2 O 4 acquired hexagonal and cubic phases, respectively. The optical band gap was reduced from 3.22 eV for pure ZnO to 3.15 eV after adding 5wt % of CoFe 2 O 4 . Addition of 1wt% CoFe 2 O 4 to ZnO matrix showed a noticeable ferromagnetic behavior that was predominant in the prepared nanocomposites and confirmed by the convex Arrott–Belov–Kouvel curves. The dielectric constant, ε ′, at higher frequencies of the investigated nanocomposites is relatively high (8–10) accompanied by low values of dielectric loss, ε ″ ranging between 0.001 and 0.003 and hence very low values of the dissipation factor D (= ε ″/ ε ′) making them applicable in the field of microwave shielding. On the other hand, the dc-conductivity, σ dc at 25 C shows a remarkable increase by Addition of 1wt% CoFe 2 O 4 to ZnO matrix and decreases gradually with further increase of the ferrite. This indicates the effect of mobility and/or the number density of charge carriers on the conductivity. The investigation at higher temperature, 150 C, shows a gradual decrease in the conductivity with increasing CoFe 2 O 4 content.