Novel blue-emitting KBaGdSi2O7:Eu2+ phosphor used for near-UV white-light LED

Abstract

Novel blue-emitting KBaGdSi2O7:Eu2+ phosphors were designed and synthesized through solid-state reaction method. The structural properties, concentration and temperature-dependent luminescence behaviors of this phosphors were investigated in detail in this paper. Studies revealed that KBaGdSi2O7:Eu2+ phosphors have an intense absorption in the broad wavelength ranging from 250 nm to 400 nm that is suitable for the commercial near-UV LED, and give out intense blue light peaked at 475 nm with a full-width half-maximum (FWHM) of 75 nm. The crystallographic information of KBaGdSi2O7 phase is revealed from XRD pattern by Rietveld refinement. Band gap is derived to be 3.93 eV through diffuse reflection spectra (DRS) through Kubelka Munk function. The concentration quenching mechanism is identified as the dipole-dipole interaction. Moreover, the thermal quenching experiment was also conducted and the activation energy is calculated as 0.3069 eV, which indicates this novel KBaGdSi2O7:Eu2+ phosphor has good thermal stability. These properties exhibit its potential commercial application for near-UV white-light LEDs (w-LEDs).

Synthesis and Characterization of Ca1–xEuxZrO3 as Environmentally Friendly Inorganic Yellow Pigments

“…In contrast, the Eu 2+ -doped Ca 1– x Eu x ZrO 3 (0.1 ≤ x ≤ 0.4) samples strongly absorbed blue light in the wavelength range from 435 to 480 nm, which is the complementary color of yellow. This optical absorption band was originated by the allowed transition between 4f and 5d orbitals of Eu 2+ . − , …”

“…This optical absorption band was originated by the allowed transition between 4f and 5d orbitals of Eu 2+ . [16][17][18]35 An enlarged view of reflectance spectra from 350 to 500 nm is shown in Figure 7b. In the x range of 0.1 ≤ x ≤ 0.3, the spectral curve shifted to the longer wavelength side as the Eu 2+ concentration increased.…”

“…Because of this situation, we focused on a divalent europium (Eu 2+ ) ion as a yellow coloring source. Eu 2+ has been generally used as an activator for phosphor materials. − KBaGdSi 2 O 7 :Eu 2+ , Sr 8 MgLn­(PO 4 ) 7 :Eu 2+ (Ln = Y and La), and Li 2 CaSiO 4 :Eu 2+ as the examples of the Eu 2+ -doped phosphors absorb the visible light in the wavelength range from 350 to 450 nm due to the electronic transition between 4f and 5d orbitals. − The energy level of the 5d orbital of Eu 2+ is strongly affected by the surrounding crystal field. Accordingly, the absorption wavelength due to the 4f–5d allowed transition depends on the host crystal structure.…”

Environment-Dependent Eu2+-Activated Ba3CaK(PO4)3 toward White-Light Emission by Chemical Cosubstitution of the (BO3)3– Anion Group

“…Moreover, the absorption edge is steadily enlarged to a longer wavelength with the introduction of (BO 3 ) 3– . In addition, the optical band gap can be evaluated by the following equations: , where F (∞), h , A , and ν represents the reflectivity, Planck constant, proportional constant, and light frequency, respectively, R is the reflectance coefficient (%), and E g represents the value of the band gap. The calculated E g values for BaCKP 3– x B x :Eu 2+ ( x = 0, 0.1, 0.2, and 0.3) are 4.92, 5.16, 4.96 and 4.84 eV, illustrating that the introduction of (BO 3 ) 3– changes the structure of the host (Figure S5).…”

“…Moreover, the absorption edge is steadily enlarged to a longer wavelength with the introduction of (BO 3 ) 3− . In addition, the optical band gap can be evaluated by the following equations: 47,48…”