Anatase-to-rutile phase transition of samarium-doped TiO2 powder detected via the luminescence of Sm3+

AbstractWe employed a sol-gel route to prepare 1% samarium-doped TiO2 nanopowders. Time-resolved photoluminescence (PL) and Raman characterization was performed. After a thermal treatment the powder crystallized in an anatase phase and revealed intense Sm3+ photoluminescence. The emission spectrum of Sm3+ exposed well-resolved crystal-field splitting enabling monitoring of the changes in the local environment.We thoroughly investigated the influence of the annealing treatment (in air) on Sm emission intensity. Annealing up to 800 ∘C led to a systematic enhancement of Sm emission. Annealing at higher temperatures, however, led to a marked weakening of Sm3+ emission and simultaneous appearance of an emission band near 830 nm. Annealing temperatures as high as 1000 ∘C were needed to induce the phase transition from anatase to rutile. It was possible to use Sm3+ as a structural probe revealinge peculiarities of the phase transition