title: Structure, Crystallographic Sites, and Tunable Luminescence Properties of Eu(2+) and Ce(3+)/Li(+)-Activated Ca1.65Sr0.35SiO4 Phosphors.
abstract: Eu(2+) and Ce(3+)/Li(+) singly doped and Eu(2+)/Ce(3+)/Li(+)-codoped Ca1.65Sr0.35SiO4 phosphors have been synthesized by a solid-state reaction method. The crystal structure was determined by Rietveld refinement to verify the formation of the αL′-Ca2SiO4 phase with the Sr addition into Ca2SiO4, and the preferred crystallographic positions of the Eu(2+) and Ce(3+)/Li(+) ions in Ca1.65Sr0.35SiO4 were analyzed based on a comparison of the unit-cell volumes and the designed chemical compositions of undoped isostructural compounds Ca(2–x)Sr(x)SiO4 (x = 0.25, 0.35, 0.45, 0.55 and 0.65). Ce(3+)/Li(+) singly activated Ca1.65Sr0.35SiO4 phosphors exhibit strong absorption in the range of 250–450 nm and a blue emission peak centered at about 465 nm. When Eu(2+) ions are codoped, the emission colors of Ca1.65Sr0.35SiO4:Ce(3+)/Li(+),Eu(2+) phosphors under the irradiation of 365 nm can be finely tuned from blue to green through the energy transfer from Ce(3+) to Eu(2+). The involved energy-transfer process between Ce(3+) and Eu(2+) and the corresponding mechanism are discussed in detail. The reported Ca1.65Sr0.35SiO4:Ce(3+)/Li(+),Eu(2+) phosphor might be a candidate for color-tunable blue-green components in the fabrication of near-ultraviolet-pumped white-light-emitting diodes (WLEDs).
authors.affiliation: †School of Materials Sciences and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Xia
authors.affiliation: ‡School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083, China.
authors.forename: Shihai
authors.initials: S
authors.lastname: Miao
authors.affiliation: †School of Materials Sciences and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Mingyue
authors.initials: M
authors.lastname: Chen
authors.affiliation: §Laboratory of Crystal Physics, Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences (SB RAS), Krasnoyarsk 660036, Russia.|∥Department of Physics, Far Eastern State Transport University, Khabarovsk 680021, Russia.
authors.forename: Maxim S
authors.initials: MS
authors.lastname: Molokeev
authors.affiliation: †School of Materials Sciences and Engineering, University of Science and Technology Beijing, Beijing 100083, China.
authors.forename: Quanlin
authors.initials: Q
authors.lastname: Liu