Origin and Luminescence of Anomalous Red-Emitting Center in Rhombohedral Ba₉Lu₂Si₆O₂₄:Eu²⁺ Blue Phosphor

Abstract

We obtain a blue phosphor, Ba9Lu2Si6O24:Eu(2+) (BLS:Eu(2+)), which shows a strong emission peak at 460 nm and a weak tail from 460 to 750 nm. A 610 nm red emission is observed for the first time in this kind of rhombohedral structure material, which is much different from the same crystal structure of Ba9Sc2Si6O24:Eu(2+) and Ba9Y2Si6O24:Eu(2+). The luminescence properties and decays from 10 to 550 K are discussed. The new red emission arises from a trapped exciton state of Eu(2+) at the Ba site with a larger coordination number (12-fold). It exhibits abnormal luminescence properties with a broad bandwidth and a large Stokes shift. Under the 400 nm excitation, the external quantum efficiency of BLS:Eu(2+) is 45.4%, which is higher than the 35.7% for the commercial blue phosphor BAM:Eu(2+). If the thermal stability of BLS:Eu(2+) can be improved, it will show promising applications in efficient near-UV-based white LEDs.

Sr‐induced color‐tunable and thermal stability enhancing in the phosphor (Ba1‐xSrx)9Lu2Si6O24:Eu2+ for solid‐state lighting

“…Because Dr value for Eu 2+ in AE1 site is 8.07%, which is smaller than that of Eu 2+ in AE2 site (11.56%) and AE3 site (13.89%), Eu 2+ preferentially occupy the crystallographic site AE1 in the end‐member compound Ba 9 Lu 2 Si 6 O 24 :Eu 2+ . These calculated results are consistent with those reported references . However, when introducing Sr 2+ ions in phosphors that is (Ba 1‐x Sr x ) 9 Lu 2 Si 6 O 24 :Eu 2+ , (x = 0.1, 0.2, 0.3, 0.4), Dr values of Eu 2+ ions for Sr 2+ ions is smaller than that for Ba 2+ ions in same coordination environment.…”

Dual-Mode Manipulating Multicenter Photoluminescence in a Single-Phased Ba9Lu2Si6O24:Bi3+, Eu3+ Phosphor to Realize White Light/Tunable Emissions

“…BLSO crystallizes in a rhombohedral structure and belongs to the (148) space group 20 . The crystal structure of the BLSO unit cell viewed from the a-axis and the c-axis is shown in Fig.…”

“…It exhibits the layered distribution in which the smaller tetrahedral SiO 4 units and the larger octahedral LuO 6 units are corner-shared as SiO 4 -LuO 6 -SiO 4 -LuO 6 , forming a rigid three-dimensional network 7 . In the crystal structure, the Lu 3+ ions are located at the 6 c Wyckoff position with 6-fold coordination, evolving a distorted LuO 6 octahedron that has two different Lu-O bond lengths 20 . While the Ba 2+ ions are designated in three independent sites: Ba(1) at the 3 a Wyckoff position with 12-fold coordination, Ba(2) at the 6 c Wyckoff position with 9-fold coordination and Ba(3) at the 18  f Wyckoff position with 10-fold coordination, forming three different distorted polyhedra with different Ba-O bond lengths.…”

“…For example, Liu et al . reported the luminescence properties of Eu 2+ -doped Ba 9 Lu 2 Si 6 O 24 blue phosphor 20 , Liu et al . investigated the high thermal and radiation stability from Ce 3+ doped Ba 9 Lu 2 Si 6 O 24 green phosphor 7 ; Song et al .…”

Structure and photoluminescence properties of novel Sr6Ca4(PO4)6F2:Re (Re = Eu2+, Mn2+) phosphors with energy transfer for white-emitting LEDs

“…[16][17][18] The Mn 2+ ions doped into a sample show a broad band emission, which was assigned from the 4 were used as the precursor materials and mixed them thoroughly for 3 h using a ball mill to obtain homogeneous samples. Aer-wards, the raw materials were transferred to alumina crucibles, with subsequently sintering at 1250 C for 4 h in reducing atmosphere, and then the as-prepared samples were cooled down to normal room temperature.…”