title: Detecting the origin of luminescence in Er3+-doped hexagonal Na1.5Gd1.5F6phosphors.
abstract: Understanding site-selective fluorescence is one of valuable importance for spectrum modulation. In this Letter, we observed the existence of two non-equivalent Gd-activated crystallographic sites in an Er3+-doped hexagonal Na1.5Gd1.5F6phosphor. It is proved that two green emissions from the S3/24 level separately originate from the Gd1 (540 nm) and Na2/Gd2 (550-555 nm) crystallographic sites, and the 657 nm red emission from the F9/24 level only originates from Na2/Gd2 site through using the time-resolved luminescence spectra. The 142.2% absolute enhancement of the red emission is realized through the synergistic effect of ultraviolet downconversion and infrared upconversion induced by the 370 nm and 1.54 μm dual-mode excitation.
authors.forename: Xiangfu
authors.initials: X
authors.lastname: Wang
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Bu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Yan
authors.forename: Peiqing
authors.initials: P
authors.lastname: Cai
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Lin
authors.initials: L
authors.lastname: Qin
authors.forename: Thiquynh
authors.initials: T
authors.lastname: Vu
authors.forename: Hyo Jin
authors.initials: HJ
authors.lastname: Seo