Cathodoluminescence study of nano-structured PbTiO3 thin films

PTO nano-powder was synthesized by a conventional solid state reaction method starting reagents of PbO (99.99%) and TiO2 (99.9%). The obtained PTO powder was finely milled and put into the well-mixed de-ionized water... [ view full abstract ]

PTO nano-powder was synthesized by a conventional solid state reaction method starting reagents of PbO (99.99%) and TiO₂ (99.9%). The obtained PTO powder was finely milled and put into the well-mixed de-ionized water solution. Then the mixture was blended quite well and atomized by using an ultrasonic generator. Resulting mists were afterwards transferred by flowing dry air on an heated silicone Si(111) substrate at  400°C in a glass chamber. Then samples were post-annealed in air atmosphere at temperatures of 700, 800 and 900°C for 1hr. A pure single-phase perovskite structure of PbTiO₃ with a mean crystalline size in the range of 32 and 38 nm was obtained. The CL spectrum exhibits four bands commonly found and denoted in literature as band (I), (II), (III), and (IV). CL measurements confirm qualitatively the tendency, well known in the literature, that emission band of PTO perovskite structure is generally located in visible spectrum 326 – 624nm. Nevertheless, a new perfect band located in UV region at 237nm (5.22 eV) has been indeed obtained here for all our PTO samples, well experimentally investigated. Then, we assume here that the wide band this is due both to the nanocrystalline quality of the films and to the quantum size effect in nano-structure.