Room-temperature photoluminescence from porous anodic alumina films with embedded terbium and europium species

Strong room-temperature terbium and europium photoluminescence, with well-resolved optical bands corresponding to electron transitions 5D4→7Fj (j = 3–6) for Tb3+, and 5D0→7Fj (j = 1–4) for Eu3+, was observed from porous anodic alumina films of 5–55 µm thickness after immersion in solutions of terbium or europium nitrates and subsequent heat treatment. GDOES and TEM examinations of the specimens treated with terbium ions revealed a uniform distribution of terbium across the porous anodic film thickness of 55 µm, with an increased terbium concentration toward the pore bases. Europium- and terbium-doped specimens displayed anisotropic indicatrix of luminescence for the emission wavelength of 613 nm for europium and 545 nm for terbium, with a maximum intensity in the direction along the channels of the pores that is typical for porous anodic alumina with lanthanide ions within the pores. The potential applications of porous anodic alumina doped with lanthanides through immersion in the absence of xerogel are discussed.