Crystal phase transformation and doping-induced blue emission of Eu-doped InOOH and cubic/corundum-type rhombohedral In2O3 nanowires

Abstract

Blue emission from orthorhombic InOOH nanowires was increased dramatically by 30-fold after doping with 1 mol% Eu. This was attributed to the reduction of Eu(III) to Eu(II), which was localized on the surface and created defects. On the other hand, a larger amount of Eu-doping did not result in strong blue emission. Corundum-type rhombohedral and cubic In₂O₃ were obtained by post-thermal annealing of the nanowires at 400 and 700 °C, respectively. Interestingly, rhombohedral In₂O₃ remained stable after doping with 10 mol% Eu even upon high temperature thermal annealing at 700 °C. The morphology was changed significantly for the undoped and 1 mol% doped samples, whereas the 10 mol% doped sample showed resistance to morphological changes upon annealing at 700 °C.