Structure and Luminescent Characteristics of Ba3Tb(PO4)3 Doped with Eu3+ Ions

Abstract

Tb, Ba). From study of the excitation spectra and the kinetics of luminescence quenching it was concluded that energy is transferred effectively from the Tb 3+ to the Eu 3+ during excitation in the UV and visible regions of the spectrum. Key words: mixed barium-terbium phosphate, Eu 3+ ions, eulitine, luminescent material. In recent years mixed phosphates with the composition M 3 II Ln(PO 4 ) 3 , with M II = Sr 2+ , Ba 2+ and Ln = Y 3+ , Cd 3+ , Tb 3+ , which crystallize in structures of the eulitine type (Bi 4 Si 3 O 12 ), have attracted increased attention on account of their use as the basis of luminophores for white light-emitting diodes [1-4] and plasma display panels [5]. Interest in the material with the composition Ba 3 Tb(PO 4 ) 3 : Eu 3+ arose from the possibility of increasing the luminescence intensity of the Eu 3+ as a result of the sensitizing effect of the Tb 3+ ions [6]. It was shown that the luminescence intensity of the Eu 3+ ions in Ba 3 Tb(PO 4 ) 3 during excitation in the ultraviolet region under vacuum is substantially higher than in Ba 3 Gd(PO 4 ) 3 . In the authors' opinion this is due to more effective energy transfer from Tb 3+ to Eu 3+ than from Gd 3+ to Eu 3+ . It should be noted that in [6] the luminescent characteristics of Eu 3+ in Ba 3 Tb(PO 4 ) 3 were only studied during excitation of luminescence in the vacuum ultraviolet region, which does not make it possible to reach a conclusion about the amount and the microstructure of the Eu 3+ luminescent centers. It is, however, known that compounds with structures of the eulitine type are characterized both by cationic [7] and by anionic (oxygen) disorder. The significant nonuniform broadening of the luminescence bands of the Eu 3+ , Eu 2+ , and Ce 3+ ions in the series of phosphates with the (Ba,Sr) 3 Ln(PO 4 ) 3 composition, where Ln = La 3+ , Eu 3+ , and Lu 3+ , have been linked to these crystal-chemical characteristics [8-10]. On the basis of the similarity in the luminescence spectra of Ce 3+ in a series of compounds with structures of the eulitine type the authors [10] came to the conclusion that the Ce 3+ ions in such structurally ordered systems can even form their own oxygen environment. The authors of [11] undertook a detailed X-ray structural investigation of Ba 3 Tb(PO 4 ) 3 single crystals grown by spontaneous crystallization and by the Czochralski method. It was shown that the Ba and Tb atoms in the Ba 3 Tb(PO 4 ) 3 structure occupy octahedral positions (16c) with distinctly different M-O 0040-5760/15/5103-0191

White light emission and energy transfer of LaMgAl11O19:Eu3+, Tb3+ phosphors

“…Figure 3 shows the solid UV‐absorption spectrum of LMA: x % Tb 3+ , y %Eu 3+ . Compared with LMA, doped with rare earth ions LMA:2%Tb 3+ , 5%Eu 3+ had higher UV‐absorption intensity, which was attributed to the electronic transition of 4f 8 → 4f 7 5d 1 of Tb 3+ and the f–f transition of Eu 3+ [3, 14]. Compared with LMA, the band gap of LMA:2%Tb 3+ , 5%Eu 3+ doped with rare earth ions decreased to 2.64 eV [14].…”

“…In recent years, phosphors doped with rare earth ions to achieve white light emission using aluminate as the substrate have advantages such as high color index, high quantum efficiency, wide excitation range, light emission in the visible range, and low cost; these phosphors are the widely studied fluorescent materials [2]. Of these, Eu 3+ and Tb 3+ are widely used because of advantages such as rich electronic energy levels, high light conversion rate, sharp linear bands, and high luminescence color purity [3,4]. Min et al [5] prepared orange-red phosphor LaMgAl 11 O 19 :Sm 3+ using the high-temperature solid-state method and studied its phase composition, crystal structure, thermal stability, and luminescence properties; Wen et al [6] prepared yellow-red phosphor LaMgAl 11 O 19 :Dy 3+ using the solid-state method.…”