Structure and fluorescent properties of TiO2:Sm3+–Ag composite

Composite based on TiO2 host doped with Sm3+ ions and co-doped with silver nanoparticles is proposed as new fluorescent material. The co-doped samples were prepared from titanium alkoxide precursor by sol–gel method adjusted for addition of Sm3+ ions and Ag nanoparticles. Commercial samarium nitrate salt and silver nanopowder (size of primary particle 30–50 nm) were used as dopant and co-dopant. Raman measurements revealed that crystalline anatase TiO2 phase is typical for the TiO2:Sm3+ films, whereas TiO2:Sm3+–Ag samples contain regions of rutile and brookite phases distributed in the predominantly amorphous TiO2 surrounding. Samarium ions were excited either directly (λexc = 488 nm) or through the TiO2 host (λexc = 355 nm). Enhancement of Sm3+ fluorescence up to 20 times was revealed in the vicinity of silver aggregates. Combined plasmonic and sensitizing influences of silver on the Sm3+ ions are considered as reasons for enhanced Sm3+ fluorescence.