title: Strong Energy-Transfer-Induced Enhancement of Luminescence Efficiency of Eu(2+)- and Mn(2+)-Codoped Gamma-AlON for Near-UV-LED-Pumped Solid State Lighting.
abstract: A series of Eu(2+)- and Mn(2+)-codoped γ-AlON (Al1.7O2.1N0.3) phosphors was synthesized at 1800 °C under 0.5 MPa N2 by using the gas-pressure sintering method (GPS). Eu(2+) and Mn(2+) ions were proved to enter into γ-AlON host lattice by means of XRD, CL, and EDS measurements. Under 365 nm excitation, two emission peaks located at 472 and 517 nm, resulting from 4f(6)5d(1) → 4f(7) and (4)T1(4G) → (6)A1 electron transitions of Eu(2+) and Mn(2+), respectively, can be observed. Energy transfer from Eu(2+) to Mn(2+) was evidenced by directly observing appreciable overlap between the excitation spectrum of Mn(2+) and the emission spectrum of Eu(2+) as well as by the decreased decay time of Eu(2+) with increasing Mn(2+) concentration. The critical energy-transfer distance between Eu(2+) and Mn(2+) and the energy-transfer efficiency were also calculated. The mechanism of energy transfer was identified as a resonant type via a dipole-dipole mechanism. The external quantum efficiency was increased 7 times (from 7% for γ-AlON:Mn(2+) to 49% for γ-AlON:Mn(2+),Eu(2+) under 365 nm excitation), and color-tunable emissions from blue-green to green-yellow were also realized with the Eu(2+) → Mn(2+) energy transfer in γ-AlON.
authors.affiliation: †College of Optics and Electronic Science and Technology, China Jiliang University, Hangzhou 310018, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Liu
authors.affiliation: †College of Optics and Electronic Science and Technology, China Jiliang University, Hangzhou 310018, China.
authors.forename: Le
authors.initials: L
authors.lastname: Wang
authors.affiliation: §Fine Particles Engineering Group, Materials Processing Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047, Japan.
authors.forename: Chenning
authors.initials: C
authors.lastname: Zhang
authors.affiliation: ⊥Graguate School of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: Yujin
authors.initials: Y
authors.lastname: Cho
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dierre
authors.forename: Naoto
authors.initials: N
authors.lastname: Hirosaki
authors.affiliation: ⊥Graguate School of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-0003, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sekiguchi
authors.forename: Rong-Jun
authors.initials: RJ
authors.lastname: Xie