Laser irradiation-induced α to δ phase transformation in Bi2O3 ceramics and nanowires

Abstract

The α-Bi2O3 to δ-Bi2O3 phase transformation has been locally induced by laser irradiation in ceramic samples and single-crystal nanowires of this oxide. The threshold power densities necessary to induce this transformation, as well as the corresponding transformation kinetics and its temporal stability, have been investigated in both kinds of samples by micro-Raman spectroscopy. The appearance of the δ phase was also monitored by spatially resolved photoluminescence spectroscopy. An emission band peaked near 1.67 eV, not observed in α-Bi2O3, is tentatively attributed to δ-Bi2O3 near band gap transitions.