Site construction of Eu2+ and sensitized luminescence of Eu3+ in LaF3:Eu nanophosphor

Abstract LaF 3 :Eu nanophosphors were prepared by a traditional hydrothermal method with citric acid as a reducing agent. X‐ray diffraction, scanning electronic microscopy, and luminescence spectroscopy were used to study the nanophosphors. The formation of three different luminescence centers of Eu 2+ and two different luminescence centers of Eu 3+ is attributed to the existence of abundant surface defects in this nanophosphor. Eu 3+ is effectively excited by energy transfer from Eu 2+ to Eu 3+ . The excitation wavelength of Eu 3+ covers a broad spectral range from 250 to 480 nm. The nanophosphor shows a tunable luminescence color varying from blue to white and then to red, which is explained from three aspects of Eu concentration, energy transfer, and concentration quenching. Utilizing the surface defect of nanoparticles to control the reduction of Eu 3+ is considered a promising strategy for exploring Eu 2+ and Eu 3+ codoped phosphor suitable for the lighting and display application.