A new disordered langbeinite-type compound, K₂Tb_1.5Ta_0.5P₃O₁₂, and Eu³⁺-doped multicolour light-emitting properties

Abstract

For the first time, a new langbeinite‐type phosphate, namely potassium terbium tantalum tris(phosphate), K2Tb1.5Ta0.5(PO4)3, has been prepared successfully using a high‐temperature flux method and has been structurally characterized by single‐crystal X‐ray diffraction. The results show that its structure can be described as a three‐dimensional open framework of [Tb1.5Ta0.5(PO4)3]∞ interconnected by K+ ions. The TbIII and TaV cations in the structure are disordered and occupy the same crystallographic sites. The IR spectrum, the UV–Vis spectrum, the morphology and the Eu3+‐activated photoluminescence spectroscopic properties were studied. A series of Eu3+‐doped phosphors, i.e. K2Tb1.5–xTa0.5(PO4)3:xEu3+ (x = 0.01, 0.03, 0.05, 0.07, 0.10), were prepared via a solid‐state reaction and the photoluminescence properties were studied. The results show that under near‐UV excitation, the luminescence colour can be tuned from green through yellow to red by simply adjusting the Eu3+ concentration from 0 to 0.1, because of the efficient Tb3+→Eu3+ energy‐transfer mechanism.

Structural and optical properties of langbeinite-related red-emitting K2Sc2(MoO4)(PO4)2:Eu phosphors

“…There are at least 8 lines (marked with arrows on the inset to Fig. 6) related with forced electric dipole (ED) radiation transition 5…”

“…4 These frameworks gained increasing attention due to their remarkable optical properties and promising application in light emitting diodes (LEDs), biomedical diagnostics, optical communication, high density optical data storage and sensors, etc. 1,[5][6][7] Mainly, these species containing PO 4 3À groups have become one of the most widely investigated families of phosphates with three dimensional (3D) frameworks since Norberg 8 has widened the group of langbeinite-related phosphates with a common formula K 2 BTi(PO 4 ) 3 , where Brare-earth metals.…”

“…1 A possibility to get luminescence with tunable colors from blue to green and yellow has been reported for K 2 Tb 1.5 Ta 0.5 P 3 O 12 :Eu 3+ and KBaSc 2 (PO 4 ) 3 :Ce 3+ /Eu 2+ /Tb 3+ compounds. 5,9 Most of the reported RE-containing derivatives of langbeinite structure show outstanding luminescent properties due to the structural peculiarities and, consequently, they have possibility of application in the white LEDs. In this area, study of the langbeinite-related compounds have been mainly focused on alkaline and lanthanide-containing systems 5,[9][10][11] owing to the simple iso-and aliovalent substitution within the cationic sites of langbeinite structure.…”

“…5,9 Most of the reported RE-containing derivatives of langbeinite structure show outstanding luminescent properties due to the structural peculiarities and, consequently, they have possibility of application in the white LEDs. In this area, study of the langbeinite-related compounds have been mainly focused on alkaline and lanthanide-containing systems 5,[9][10][11] owing to the simple iso-and aliovalent substitution within the cationic sites of langbeinite structure. Meanwhile, the designed assembly of poly-oxoanionic frameworks is seen to be more difficult to obtain due to stability that inherent to langbeinite structure.…”