The Properties of ZnO Nanopowders Obtained by Sinthesis in Solar Reactor

Full text: ZnO nanopowders were synthesized in France using vaporization-condensation process inside the Solar reactor [1]. As a raw material the ZnO powder (MERCK, 99% purity) was used. Synthesis was performed at different pressure inside the reactor (P=20 - 120 Torr). XRD, SEM, BET and luminescence methods were used for powders investigation. It is shown that nanoparticles microstructure depends on the pressure inside the reactor: in starting material regular hexagonal form nanoparticles with different sizes (10-60 nm) were observed, but in synthesized powders the whiskers (l ∼ 350 nm, d∼ 60 nm) were observed. Powder morphology depends on the pressure inside the reactor and increasing pressure the average grain size increase. XRD analysis shows, that the crystallographic cell is elongated along the c-axis when the pressure inside the reactor increases. It is shown that exciton luminescence intensity depends on the pressure inside the reactor and grows with pressure up to 60 Torr. At higher pressures the luminescence intensity is close to constant. The luminescence decay kinetics in exciton and defect bands region was studied. The ratio of luminescence intensities for those bands depends on the pressure inside the reactor. Analyzing the obtained results recommendations for nanopowders synthesis in solar reactor was given. (Authors)