Influence of Co-doping on the structural, optical and morphological properties of Zn0.96Mn0.04O nanoparticles by sol–gel method

• Zn0.96−xMn0.04CoxO nanoparticles were successfully synthesized.
• 2Co2+ into Zn–Mn–O lattice was confirmed by EDX, FTIR and optical studies.
• Tuning of energy gap and transparency in visible region is useful for industrial application.

Zn0.96−xMn0.04CoxO (0 ⩽ x ⩽ 0.08) nanoparticles were successfully synthesized by sol–gel method. The structural and optical properties of the samples were investigated by X-ray diffraction and UV–visible photo-spectrometer. The X-ray diffraction results and c/a ratio revealed that the hexagonal wurtzite structure of ZnO is not affected by Mn/Co doping. The decreased average crystal size from 21.9 nm (Co = 0%) to 16.8 nm (Co = 6%) was due to the increase of tensile stress. The energy dispersive X-ray spectra showed the excellent oxide formation and the presence of Mn and Co in ZnO. The observed green band around 492 nm for Co = 2% and 482 nm for Co = 4% were originated from oxygen vacancies and intrinsic defects. The high optical transmittance (>70%) in visible region indicated the good optical quality crystal. The optical energy gap might be tuned by changing the Co concentration. The Fourier transform infrared spectroscopy analysis showed the stretching vibrations and the oxide formations.