Temperature Dependent Quantum Cutting in Cubic BaGdF5:Eu3+ Nanophosphors

Task-specific ionic liquid (IL) is employed as a structure directing agent for the synthesis of quantum cutting BaGdF5:Eu3+ nanophosphors. Herein, IL and temperature dependent quantum cutting is observed. Maximum (160%) and minimum (123%) quantum cutting efficiency (QCE) are obtained in the presence and absence of IL, respectively, at room temperature (295 K). However, at low (10 K) temperature, emission spectrum is dominated by Eu2+ 5d-4f emission which is further confirmed by X-ray excited luminescence study. It is also observed that decay kinetics recorded for Eu2+ 5d-4f emission demonstrate longer (with lifetime from 580 ns to 1.5 s) and faster (with lifetime from 35 to 50 ns) decay components related to normal and surface quenched emission, respectively. In addition, maximum quantum yield (η = 73.5%) is obtained for the sample prepared in the presence of IL than that of sample prepared without IL (η = 65%). The easy yet highly phase selective green synthesis of the materials promises large scale industrial application in nanothermometry as well as in environmentally benign energy efficient lighting.