title: Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.
abstract: Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.
authors: Graduate School of Advanced Engineering, Silla University , Busan 46958, Republic of Korea.
authors: Donghyeon
authors: D
authors: Kim
authors: Department of Chemistry, Division of Energy Systems Research, Ajou University , Suwon 16499, Republic of Korea.
authors: Sung-Chul
authors: SC
authors: Kim
authors: Busan Center, Korea Basic Science Institute , Busan 46742, Republic of Korea.
authors: Jong-Seong
authors: JS
authors: Bae
authors: Institute of NT.IT Fusion Technology, Ajou University , Suwon 16499, Republic of Korea.
authors: Sungyun
authors: S
authors: Kim
authors: Department of Chemistry, Division of Energy Systems Research, Ajou University , Suwon 16499, Republic of Korea.
authors: Seung-Joo
authors: SJ
authors: Kim
authors: Graduate School of Advanced Engineering, Silla University , Busan 46958, Republic of Korea.|Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University , Busan 46958, Republic of Korea.
authors: Jung-Chul
authors: JC
authors: Park