Characterization of europium doped zinc aluminate luminescent coatings synthesized by ultrasonic spray pyrolysis process

摘要

Europium doped zinc aluminate (ZnAl_2O_4) photoluminescent films have been deposited by ultrasonic spray pyrolysis deposition process. Different substrate temperatures and doping concentrations in the start spraying solution were studied. It is observed that the crystalline structure of this material depends on the substrate temperature during deposition of the films. For low substrate temperatures, the deposited films are amorphous. When the substrate temperature is increased at 500℃ some peaks corresponding to hexagonal phase of ZnO (zincite) appears. At substrate temperatures of 550℃, the crystalline structure of the ZnAl_2O_4:Eu films presents the close-packed face centered cubic phase. The excitation and emission spectra were obtained; for an excitation wavelength of 260 nm, all the photolu-minescence (PL) spectra show peaks located at 589, 615, 652 and 700 nm. Concentration quenching of the PL occurs at activator concentrations greater than 0.85 at.% inside the deposited films. The PL intensity increases as the substrate temperature rises. In addition, the surface morphology features of the films, as a function of the deposition temperature, are shown.