Strong photoluminescent emission has been measured at room temperature for noncrystalline $\mathrm{Ba}\mathrm{Ti}{\mathrm{O}}_3$ (BT) perovskite powders. A joint experimental and theoretical study has been carried out to rationalize this phenomenon. From the experimental side, BT powder samples have been synthesized following a soft chemical processing, their crystal structure has been confirmed by x-ray data and the corresponding photoluminescence (PL) properties have been measured. Only the structurally disordered samples present PL at room temperature. From the theoretical side, first-principles quantum-mechanical techniques, based on density-functional theory at the B3LYP level, have been employed to study the electronic structure of crystalline (BT-$\mathrm{c}$) and asymmetric (BT-$\mathrm{a}$) models. Theoretical and experimental results are found to be consistent and their confrontation leads to an interpretation of the PL apparition at room temperature in the structurally disordered powders.

• Received 15 July 2004

DOI:https://doi.org/10.1103/PhysRevB.71.085113