Photoluminescence Characteristics of Eu³⁺-Doped Double-Perovskite Phosphors

Abstract

Eu 3+ -doped triple tellurium double perovskites LiBaLa [TeO 6 ], NaBaLa [TeO 6 ], LiBaBi [TeO 6 ] and NaCaBi [TeO 6 ] were synthesized by the general high temperature solid-state reaction. The crystal phase formations and morphology of the phosphates were confirmed by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) measurements, respectively. The luminescence properties, including the photoluminescence (PL) excitation and emission spectra, decay curves (lifetimes), the color coordinates and the internal quantum efficiency (QE) were investigated. Eu 3+ -doped LiBaLa[TeO 6 ], NaBaLa[TeO 6 ], and LiBaBi[TeO 6 ] show the dominated electric dipole transition 5 D 0 → 7 F 2 with a pure red luminescence color and a fast decay. However, Eu 3+ -doped NaCaBi[TeO 6 ] presents the dominant reddish-orange emission from magnetic dipole transition 5 D 0 → 7 F 1 and a longer luminescence lifetime. The different luminescence features were discussed on the base of crystal structure, where Eu 3+ ions have two possible substitutions on A or B sites in double tellurium perovskites.ABO 3 compounds with perovskite structure are the most studied ferroelectric materials in the past years. 1-6 This well-known structure has a three-dimensional corner-sharing network of BO 6 octahedra with a large A-cation cavity occupying the AO 12 cuboctahedral. It is an important way to obtain high density samples with near optimal piezoelectric properties by doping rare earth ions (RE) in perovskites. 7 This brings another important research topic for perovskites, i.e., the luminescence properties. RE-doped perovskites as Eu 3+ -doped CaTiO 3 , 8,9 BaZrO 3 , 10 PbTiO 3 , 7 etc, have promising applications in luminescence and displays. [11][12][13] The great flexibility of A and B sites in ABO 3 allows very rich substitutions. This induces a large number of isotopic compounds with perovskite structure such as double perovskite oxides with a general formula A 2 B B O 6 in which B O 6 and B O 6 octahedra are corner-shared alternately. This framework forms cube-octahedral cavities filled by A-site cations. 14,15 Eu 3+ -doped double perovskite oxides have been given great attentions because of the possible applications as luminescence materials such as MgTiO 6 :Eu 3+ , 23 A 2 CaMoO 6 (A = Sr, Ba), 15 A 2 CaWO 6 (A = Sr, Ba) and Sr 1.9−x Ba x Eu 0.05 Li 0.05 MoO 6 (x = 0-1.9). 24 Eu 3+ -doped double perovskites have a broad excitation band ranging from ultraviolet to visible light region, and show efficient red luminescence. The studies have shown that the emission intensity of Eu 3+ -doped Sr 2 CaMoO 6 is 1.5 times higher than that of commercial Y 2 O 2 S:Eu 3+ ; 15 Sr 1.5 Eu 0.05 Li 0.05 Ba 0.4 CaWO 6 has 4.5 times stronger luminescence intensity than that of commercial red phosphor (Nichia) under 465 nm excitation. 24 In this study, new red-emitting phosphors of Eu 3+ -doped tellurium perovskites LiBaLa[TeO 6 ], NaBaLa[TeO 6 ], LiBaBi[TeO 6 ] and NaCaBi[TeO 6 ] were synthesized by the conventional high temperature solid state reac...

Effect of Different Heating Process on the Photoluminescence Properties of Perovskite Eu-Doped BaZrO3 Powder

“…For two-step Eu-BZO powders, the domination transition changed from 5 D0 → 7 F1 to 5 D0 → 7 F0 as the heating temperature increased from 1100 °C to 1400 °C; also, the emission changed from the reddish-orange color to orange, as Figure 6a-c show. [16]. Those results suggest that the different Eu 3+ ion transitions will happen.…”

“…Those photographs prove that Eu-BZO phosphors with very bright emission intensity can easily be obtained by heating oxide precursors. Yu et al found that Eu 3+ -doped LiBaLaTeO6, NaBaLaTeO6, and LiBaBiTeO6 show the dominant transition of 5 D0 → 7 F2 with a pure red luminescence color and Eu 3+ -doped NaCaBiTeO6 presents the dominant reddish-orange emission from the transition of 5 D0 → 7 F1 [16]. Those results suggest that the different Eu 3+ ion transitions will happen.…”

“…where the lifetime τ refers to the time required for the intensity to drop to I 0 /e, I 0 is the initial intensity, and I em is the intensity at time t. Yu et al also found that Eu 3+ -doped LiBaLaTeO 6 , NaBaLaTeO 6 , and LiBaBiTeO 6 show a fast decay and Eu 3+ -doped NaCaBiTeO 6 presents a longer luminescence lifetime [16]. As Figure 7 shows, the one-step Eu-BZO phosphors exhibited decay lifetimes extending from 2.52 ms to 3.98 ms and the two-step Eu-BZO phosphors exhibited decay lifetimes extending from 3.78 ms to 6.02 ms. As we know in Zn 2 SiO 4 -MnO 2 phosphors, if too much MnO 2 dopant is added, a concentration quenching effect occurs, with resulting degeneration of the emission intensity and decay time [20,21].…”

“…They found that those double-perovskite powders show the dominated electric dipole transition 5 D 0 Ñ 7 F 2 with a pure red luminescence color and a fast decay. They also found that Eu 3+ -doped NaCaBi [TeO 6 ] presents the dominant reddish-orange emission from the magnetic dipole transition 5 D 0 Ñ 7 F 1 and a longer luminescence lifetime [16]. In the past, Kanie et al synthesized Eu-doped BaZrO 3 fine particles with high crystallinity by using hydrothermal reactions and they also investigated the effect of size and shape on the fluorescence properties of Eu-doped BaZrO 3 for its use as a phosphor [17].…”

Structure and tunable blue-white-red luminescence of Eu2+/Eu3+-doped Na5Al(PO4)2F2 single-phase phosphor

“…Eu 3 þ shows red-luminescence (570À 750 nm) from the intra-configurational 4f 6 -4f 6 parity forbidden transitions with narrow peaks of 5 D 0 -7 F J (J ¼0-4) with lifetime in ms scale [3]. However, Eu 2 þ has broad emission from the parity allowed transitions 4f 6 5d 1 -4f 7 with fast decay (ns scale) [4][5][6].…”