Preparation conditions and optical properties of rare earth ion (Er3+ and Eu3+)-doped alumina films by the aqueous sol-gel method

Transparent alumina and rare earth ion (Er3+ and Eu3+) highly doped alumina films (15 mol %) were prepared by the aqueous sol-gel method, in order to examine the effects of various preparation conditions on the structure and optical properties of doped films. The results showed that when the gel was heat treated, it lost free and bound water and was converted into the oxide by way of a series of intermediate phases although the oxide as a whole remained structureless. The thermogravimetric analysis curve showed a marked weight loss in the temperature range of 100-500 degreesC and the slow loss continuing at higher temperature of 800 degreesC. High doping may reflect noncrystalline structure of alumina. The fluorescence of Eu3+ sensitive of microstructure increased especially corresponding to this weight loss with treatment. The Omega (2) indicative of the asymmetric environment of Er3+ showed a similar increase. Concentration quenching for doped films treated at 800 degreesC was not significant in this concentration range. Lifetimes increased with increasing treatment temperature, similar to above increase. (C) 2001 American Institute of Physics.