Rare earth elements terbium (Tb), erbium (Er), ytterbium (Yb) doped zinc oxide nanoparticles: Synthesis structural optical and gas sensing studies

In the present study, co-precipitation process is used to synthesize pure zinc oxide (ZnO) and doped ZnO nanoparticles containing the rare earth (RE) elements terbium (Tb), erbium (Er), and ytterbium (Yb). Studies using X-ray diffraction (XRD) demonstrated the existence of ZnO hexagonal wurtzite structure. Fourier transform infrared (FT-IR) analysis was used to validate the structural coordination and the existence of different organic functional groups in the ZnO structure of both undoped and RE-doped ZnO samples. The morphology of RE- doped ZnO samples was irregularly ordered grains with distinctive grain boundaries, as seen by field emission scanning electron microscopy (FESEM). When comparing Tb-doped ZnO (3.20 eV) to pure ZnO (3.27 eV), a decrease in the optical band gap was observed. Photoluminescence (PL) emission spectra exhibits five emission peaks at 416, 440, 451, 478, and 523 nm and the raise in intensity of the blue emission peak confirms the presence of increased oxygen vacancies for the Tb doped ZnO sample. Among all the fabricated ammonia gas sensors based on RE-doped ZnO, the Tb-doped ZnO sample had the highest gas response value of 609 % and a better response/recovery times of 7.64/4.87 s at ambient temperature, suggesting the suitability of the device for commercial gas sensing application.