Synthesis of the Red-Emitting (Ba, Ca)₂ScAlO₅:Eu³⁺ Phosphors with Photoluminescence Properties

Abstract

The light-emitting diodes (LED) are regarded as one of the most promising devices for inexpensive and widely used illumination; in particular, they are highly dependent on the development of red-emitting phosphors. Herein, we developed two types of red-emitting (Ba, Ca) 2 ScAlO 5 :Eu 3+ multiple excitations phosphors (λ ex = 255−465 nm) via freeze-drying followed by calcination. Powder X-ray diffraction and NMR results point out that they have hexagonal space group P6 3 /mmc (194), and the structural framework is composed of multi-coordinated Al 3+ −O 2− polyhedron and Sc 3+ −O 2− polyhedron. In addition, the valence state of europium (Eu 3+ ) is confirmed by X-ray photoelectron spectroscopy characterization. Investigation on the photoluminescence properties showed that the photoluminescence process of (Ba, Ca) 2 ScAlO 5 :Eu 3+ is attributable to the charge transfer band of Eu−O and abundant spectral terms of Eu 3+ . The α-(Ba, Ca) 2 ScAlO 5 :Eu 3+ and β-(Ba, Ca) 2 ScAlO 5 :Eu 3+ exhibited red emission under 465 and 395 nm excitation, respectively. The PL spectra and decay curves explain the intrinsic photoluminescence mechanism. The strongest emission peaks of the red-emitting α-(Ba, Ca) 2 ScAlO 5 :Eu 3+ and β-(Ba, Ca) 2 ScAlO 5 :Eu 3+ phosphors are at 615 and 619 nm, respectively, exhibiting a high fluorescence of 64 and 67% under the temperature of 423 K (150 °C). Further exploration of the red-emitting phosphors would provide a variety of choices for the design of red LEDs and white LEDs for the solid-state lighting system.

Layered structure-induced quenching delay toward highly efficient and thermally stable red emission in Eu3+-activated borotellurate phosphors

“…36 The 5 D 0 → 7 F 1 magnetic dipole (MD) transition at 592 nm is scarcely affected by the crystal field of Eu 3+ . 37 To reflect the relationship between the symmetry of the [Y/EuO 7 ] polyhedron and the Eu 3+ doping content, the emission transition ratio of 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 (R/O) is shown in Fig. 6(d).…”

Wide-band excited and deep-red sensitized Mn2+ emission from an NaSrSc(BO3)2:Eu2+,Mn2+ phosphor with vanished Eu2+ emission

“…7,8 As for luminescent centers, the widely used trivalent rare-Earth ions (Eu 3+ , Sm 3+ , and Pr 3+ ) have the disadvantages of weak absorption and narrow band emission, which further limit the range of practical application. 9,10 It is well known that Mn 2+ could generate emission in the green, red and deep-red regions from 3d-3d transitions, whose shape is broadband, and the corresponding wavelengths are determined by the coordinated environment of its occupied sites. 11,12 Therefore, the emitting color of Mn 2+ -activated red phosphors could be tuned from orange to infrared compared with other red luminescent ions (Eu 3+ , Mn 4+ ).…”

CaAl2Si2O8:Dy3+, Eu3+: synthesis, luminescence properties, energy transfer, and tunable emission

“…16 Eu 3+ ion exhibits orange and pure red emissions because of the transitions from the excited state 5 D 0 to the ground states 7 F J ( J = 0, 1, 2, 3, 4, and 5) in the 4f 6 electron configuration. 17 There are a number of research studies on Eu 3+ -doped luminescent materials, such as Ca 3 La 6 Si 6 O 24 :Eu 3+ , 18 Na 2 Ln 4 (MoO 4 ) 7 : Eu 3+ [Ln = La, Gd, and Y], 19 (Ba, Ca) 2 ScAlO 5 :Eu 3+ , 20 Ca 9 MgLi (PO 4 ) 7 :Eu 3+ , 21 and (Sr, Ba) 2 YTaO 6 :Eu 3+ . 22 From the above Dy 3+ or Eu 3+ -doped luminescence materials, we can find that there is a spectral overlap between the emission spectrum of Dy 3+ -doped luminescence materials and the excitation spectrum of Eu 3+ doped luminescence materials, implying that energy transfer can occur from Dy 3+ to Eu 3+ ions.…”

“…Eu 3+ ion exhibits orange and pure red emissions because of the transitions from the excited state 5 D 0 to the ground states 7 F J ( J = 0, 1, 2, 3, 4, and 5) in the 4f 6 electron configuration. 17 There are a number of research studies on Eu 3+ -doped luminescent materials, such as Ca 3 La 6 Si 6 O 24 :Eu 3+ , 18 Na 2 Ln 4 (MoO 4 ) 7 :Eu 3+ [Ln = La, Gd, and Y], 19 (Ba, Ca) 2 ScAlO 5 :Eu 3+ , 20 Ca 9 MgLi(PO 4 ) 7 :Eu 3+ , 21 and (Sr, Ba) 2 YTaO 6 :Eu 3+ . 22…”