title: The effect of high-temperature annealing on optical properties of porous anodic alumina formed in oxalic acid.
abstract: Photoluminescence (PL) of anodic alumina membranes (AAMs) with ordered nanopore arrays fabricated in oxalic acid has been investigated under different annealing temperatures. X-ray diffraction reveals the structural transition from the amorphous state to crystallization. PL measurements show that a blue PL band occurs in the wavelength range 300-600 nm. The differential thermal analysis (DTA) and thermogravimetric analysis (TG) results revealed plentiful oxalic ions incorporated into the prepared AAMs. The PL band of AAMs could be attributed to the co-actions of the oxygen vacancies (F(+) and F centres) and the luminescent centres transformed from oxalic impurities. With the increase of the annealing temperature, the intensities of PL increase first, and at 500 degrees C reach a maximum value, then decrease. The PL phenomenon is intimately related to the temperature-induced structural transitions. There are three optical centres in the annealed AAMs; the first is originates from the F centres, the second is correlated with F(+) centres and the third is associated with the oxalic impurities incorporated in the AAMs.
authors.affiliation: College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, People's Republic of China. lizhaojian_lzj@hotmail.com
authors.forename: Zhaojian
authors.initials: Z
authors.lastname: Li
authors.forename: Kelong
authors.initials: K
authors.lastname: Huang
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D002623:Chemistry Techniques, Analytical / Q000379:methods; D006358:Hot Temperature; D049449:Luminescence; D008567:Membranes, Artificial; D049329:Nanostructures; D009904:Optical Rotation; D019815:Oxalic Acid / Q000737:chemistry*; D016062:Porosity
chemical_list: D008567:Membranes, Artificial; D019815:Oxalic Acid; D000537:Aluminum Oxide