Luminescent materials based on thin metal oxide films doped with rare earth ions

Abstract

Luminescent films of TiO2: Sm were prepared by the sol-gel method using the spray pyrolysis technique. Various techniques (including IR absorption, Raman, AFM, XPS, photoluminescence) were used to characterize the samples. After a thermal treatment up to 750°C, intense Sm3+ luminescence with a well-resolved fine structure was observed under optical excitation within the fundamental absorption band of the TiO2 host. After further thermal treatments up to 950°C, the luminescence was quenched, although no anataseto-rutile phase transformation was observed. This behavior is attributed to nanocrystallinity and segregation of Sm ions in the surface layer.