The effect of high-temperature annealing on optical properties of porous anodic alumina formed in oxalic acid

摘要

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 FAIL 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. Copyright (C) 2007 John Wiley & Sons, Ltd.