Effect of high-temperature annealing on photoluminescent properties of anodic alumina

• Main Authors: Mukhurov, Nikolai, Gasenkova, Irina, Zhvavyi, Sergei, Kolesnik, Eduard, Andrukhovich, Irina
• Format: Conference Proceeding
• Language: English
• Subjects: Aluminum oxide; Annealing; Electrochemical oxidation; Electrolytes; Excitation spectra; High temperature; Metal foils; Oxalic acid; Photoluminescence; Properties (attributes)
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0034304

A study has been conducted on the influence of high-temperature annealing in air and in vacuum on the photoluminescent (PL) properties of anodic alumina (AA). The AA samples 40 µm thick were prepared by electrochemical oxidation of aluminum foil (99.99%) in an oxalic acid-based electrolyte (0.3 M) in the galvanostatic mode at a current density of 7 mA/cm2 and electrolyte temperature of 15 °C. The samples were annealed at temperatures Ta = 900 and 1000 °C with holding at a constant temperature for 30 min. Analysis of the obtained PL spectra and photoluminescence excitation (PLE) spectra showed a significant change in the intensity and shape of the PL spectra of the annealed samples as compared to the original ones. Shifting of the spectral maxima is observed with a simultaneous significant decrease in the PL intensity. A distinctive feature of the spectra of the samples annealed in vacuum is the shift of their maxima at 515 - 575 nm, which is characteristic of the F2−type centers. For the samples annealed in air, the PL maximum is located in the 420 nm region and is due to single vacancies. Photoluminescent properties of the annealed AA are determined by a decrease in the number of F- and F2−type centers in the structural transition from amorphous to polycrystalline Al2O3.