Strongly enhanced Tb luminescence from titania xerogel solids mesoscopically confined in porous anodic alumina

We report strongly enhanced Tb photoluminescence (PL) from a doped titania xerogel deposited on mesoporous anodic alumina. Transmission electron microscopy has confirmed the presence of the xerogel inside the pores of alumina films of up to several microns thickness. The optical bands attributed to D35→Fi7 (i=3,4,5), D45→Fj7 (j=3,4,5,6) transitions of Tb3+, with a predominant band at 2.28 eV, are investigated between 6 and 300 K. At all temperatures, the Tb PL increases and the bands become narrower with an increase in the Tb concentration in the xerogel, the number of deposited layers employed and the thickness of the porous alumina film.