^aDepartment of Nanoscience and Technology, KS Rangasamy College of

Technology, Tiruchengode – 637 215, Tamil Nadu, India

^bDepartment of Physics, Sona College of Technology, Salem – 636 005,

Tamilnadu, India

^cDepartment of Physics, Alagappa Chettiar Government College of Engineering and Technology, Karaikudi – 630 003, Tamilnadu, India.

Chromium doped Zinc oxide (Zn0.96Cr0.04O), Chromium and Copper co-doped ZnO nanoparticles (Zn0.96Cr0.04Cu0.02O & Zn0.96Cr0.04Cu0.04O) successfully synthesized by chemical precipitation method at 5000C. The crystalline structure, surface morphology and optical properties of the prepared Cr/ZnO and Cr/Cu/ZnO nanoparticles were examined as a function of doping substance and the prepared samples were characterized using XRD, SEM, EDS and UV-Vis spectroscopy analysis. The synthesized nanoparticles show hexagonal wurtzite structure, and the phase segregation takes place for Cu doping. Optical studies revealed that Cr doping increases the energy band gap while Cu incorporation results in decrease of the band gap.