Fast synthesize ZnO quantum dots via ultrasonic method

Abstract

Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots.

Pressure Effects on the Percolation Behavior of Systems Based on Polyethylene Oxide and Carbon Nanotubes

“…The obtained results qualitatively agree with the experimental data of work [19]. Namely, it was found that the ultrasonic treatment of semiconductor quantum dots for 5-90 min in the course of their synthesis allows one to obtain nanoclusters that are more uniform by dimensions.…”

Adjusting the band structure and defects of ZnO quantum dots via tin doping

“…Zn 1Àx Sn x O QDs were obtained aer continuous ultrasonication (ultrasonic frequency ¼ 53 kHz, ultrasonic power ¼ 180 W) to promote the reaction at 40 C for 30 min. Then, 0.6 mL of oleic acid (OA) 14,15 was used to precipitate the QDs. The white sediment was centrifuged for 5 min at 4000 rpm for 2-3 times and then washed with excess ethanol to remove any unreacted material.…”

Supercritical CO2 drying of alginate/zinc hydrogels: a green and facile route to prepare ZnO foam structures and ZnO nanoparticles

“…Several methods have already been developed to synthesise ZnO (powder or thin lms), especially to control its morphology and porous texture, mainly by the following processes: chemical vapor deposition, 24 radio frequency magnetron sputtering, 25 spray pyrolysis, 26 molecular beam epitaxy, 27 pulse laser deposition, 28 atomic layer deposition, 29 hybrid-vapor phase epitaxy, 30 metal-organic vapor phase epitaxy, 31 vapor-phase synthesis, 32 synthesis from the melt, 33 hydrothermal synthesis, 34 precipitation, 35 co-precipitation, 36 and sol-gel 37 and sol-gel assisted ultrasonic methods. 38 In line with this, several morphological forms of zinc oxide including nanorods, nanotubes, hollow structures, nanocubes, ower-like structures, and nanospheres were prepared. 39 Ungula et al have synthesized ZnO nanoparticles via a sol-gel mineralization process using a sol-gel method with a systematic characterization by several analytical techniques to investigate the effect of the volume ratio of water versus ethanol on the structural, morphological and optical properties of ZnO nanoparticles.…”