Structural and fluorescence studies of polycrystalline α-Al2O3 obtained on anodic alumina

Abstract

In the present study we obtained robust α-Al2O3 films (144 μm thick) films by the heat treatment at 1200–1400 °C of free-standing anodic alumina and studied their physical chemical and fluorescence properties. According to steady-state fluorescence measurements both the as-anodized and heat treated at 1400 °C films are characterized by a broad fluorescence in the wavelength range of 400–650 nm. The time-resolved fluorescence data show that with increasing treatment temperature the average life time of the centers increases from 3.5 to 4.5 ns. It is caused by the refining of alumina structure and formation of α-Al2O3. The origin of the fluorescence is believed to be due to the presence of hydroxyl groups.