Optical characteristics of Tb-doped InBO3 nanocrystals

InBO3 nanocrystals doped with Tb3+ ions are prepared via the sol–gel method. The structure, morphology, and optical properties of the nanocrystals are characterized by X-ray diffraction, high-resolution transmission electron microscopy, field-emission scanning electron microscopy, and photoluminescence analysis. The results show that a hexagonal InBO3 phase forms at above 650 °C. A second phase of In2O3 begins to appear with Tb doping of over 3 mol%. The 5D4→7F5 (553 nm) transitions of Tb3+ ions in the InBO3 host are observed at 2 mol%. The decay time of Tb-doped InBO3 nanocrystals is about 2.1 ms. For Tb-doped InBO3 nanocrystals excited at 237 nm and 553 nm wavelengths, the 2 mol% doping level yields the highest saturation of green emission. The emission shifts from green to yellow when the doping concentration is increased from 1 to6 mol%, due to the 5D4→7F5 transition.