In this work, X-ray diffraction analysis and optical properties of pure and Ba-doped ZnO nanoparticles
prepared by the precipitation method were investigated. X-ray analysis was employed to evaluate the
micro structural parameters of ZnO nanoparticles in terms of crystallite sizes and lattice strain by the
Williamson–Hall method. The average crystallite size of Ba-doped ZnO nanoparticles estimated by the
Williamson–Hall method varied as the doping concentration increased. The effect of Ba doping on the
photoluminescence (PL) emission spectrum of ZnO was also investigated. The temperature dependence
of the PL emissions was also studied, and it was found that at low temperature, the samples show
stronger emissions than those at room temperature in both UV and visible regions. As a final point, the
FT–IR reflection spectrum along with Kramers–Kronig (K–K) method and classical dispersion theory was
applied to obtain optical properties of the samples at low frequency infrared regime
