Synthesis of Composite Films in Tb2O3–Al2O3 Eutectic System by CVD method and Their Tb3+-centered Luminescence

Composite films in the Tb 2 O 3 -Al 2 O 3 eutectic system were synthesized on sapphire substrates by the laser-assisted chemical vapor deposition method.On a c-cut sapphire substrate, TbAlO 3 (TAP)--Al 2 O 3 and Tb 3 Al 5 O 12 (TAG)--Al 2 O 3 composite films were obtained at 6.4-39.6 mol%Tb 2 O 3 in precursor vapor.At compositions close to the eutectic point of 22.0 mol%Tb 2 O 3 , a lamellar structure formed, whereas at compositions far from the eutectic point, a rod-like structure formed.Both TAP--Al 2 O 3 and TAG--Al 2 O 3 composite films exhibited green luminescence originating from the 5 D 4 -7 F n (n = 3-6) transitions of Tb 3+ centers with decay time constants of 0.67 and 1.46 ms for the TAP--Al 2 O 3 composite film and 0.75 and 1.31 ms for the TAG--Al 2 O 3 composite film.