Effect of heat treatment in vacuum on photoluminescence of anodic alumina

Abstract

The results are presented of a study of the photoluminescent (PL) properties of an undoped porous anodic alumina (PAA) and PAA doped with manganese ions. The PAA samples were prepared by anodization of aluminum. The effect of annealing conditions in vacuum on the PL spectra was studied for the first time and a comparative analysis was made with the spectra of the PAA annealed in air. Vacuum annealing was used to obtain oxygen-deficient alumina. A strong dependence of the PAA PL intensity on the annealing temperature in vacuum has been found: for the samples annealed at 600°С, the PL intensity is 15 times higher than that measured on the initial samples, whereas for the samples annealed in air it increases only 4.5-fold with excitation at the wavelengths of 275 nm. This is the result of the formation of a high concentration of oxygen vacancies during annealing in vacuum under conditions of oxygen deficiency as compared with the samples annealed in air, where diffusion of oxygen from air leads to a decrease in vacancies. A significant increase in the PL intensity permits consideration of the vacuum-annealed PAA as a promising material for dosimetry.

Photoluminescence properties of anodic aluminium oxide films formed in a mixture of malonic acid and oxalic acid

“…[13,14] The optical characteristics of AAO films, especially their PL properties, have been directly related to many factors including electrolyte composition, anodization temperature, anodization voltage, and time, as well as the purity of the aluminium, the anodization process, and the annealing treatment. [15][16][17][18][19] During the anodization process, the type and concentration of the electrolyte is one of the most important factors under consideration. The most common studies have been on the PL or microstructure of AAO films fabricated in sulfuric, oxalic, and phosphoric acids, [20][21][22] and there have been many studies on the use of other acidic electrolytes such as malonic, selenic, citric, malic, etidronic, and tartaric acid under anodization.…”