Investigation on structural, optical and dielectric properties of Co doped ZnO nanoparticles synthesized by gel-combustion route

We report the synthesis of Co doped ZnO nanoparticles by combustion method using citric acid as a fuel for 0%, 1%, 3%, 5% and 10% of Co doping. The structural, optical and dielectric properties of the samples were studied. Crystallite sizes were obtained from the X-ray diffraction (XRD) patterns whose values are decreasing with increase in Co content up to 5%. The XRD analysis also ensures that ZnO has a hexagonal (wurtzite) crystal structure and Co2+ ions were successfully incorporated into the lattice positions of Zn2+ ions. The TEM image shows the average particle size in the range of 10–20 nm for 3% Co doped ZnO nanoparticles. The energy band gap as obtained from the UV–visible spectrophotometer was found gradually increasing up to 5% of Co doping. The dielectric constants (ɛ′, ɛ″), dielectric loss (tan δ) and ac conductivity (σac) were studied as the function of frequency and composition, which have been explained by ‘Maxwell Wagner Model’.

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► We prepared Co doped ZnO by facile gel-combustion method.
► Studied the structural, morphological, optical and dielectric properties in detail.
► Band gap increases with Co concentration up to 5%.
► Dielectric constant and loss decreases with increase in frequency and concentration.
► Impedance shows single circular arc suggesting grain boundaries effect.