Color‐Tunable Luminescence of Y₄Si₂N₂O₇:Ce³⁺, Tb³⁺, Dy³⁺ Phosphors Prepared by the Soft‐Chemical Ammonolysis Method

Abstract

Ce3+‐, Tb3+‐, and Dy3+‐activated Y4Si2N2O7 phosphors have been prepared by the Pechini‐type sol–gel method followed by ammonolysis of the precursors. The phase purity, morphology, crystallization condition, chemical composition, and thermal stability of the products have been studied carefully by X‐ray diffraction (XRD), energy‐dispersive X‐ray (EDX), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM), fourier‐transform infrared (FTIR), and thermogravimetry analysis (TGA) techniques. The photoluminescence (PL) and cathodoluminescence (CL) properties of Ce3+‐, Tb3+‐, and Dy3+‐doped Y4Si2N2O7 phosphors were also investigated. The electronic structure of Y4Si2N2O7 has been investigated by density‐functional theory methods. The calculations revealed that the nitrogen atom contributes more excited electrons than the O atom. The band gap has been calculated through the reflection spectrum of the Y4Si2N2O7 host. For Ce3+/Tb3+/Dy3+ singly doped Y4Si2N2O7 products, the phosphors give the typical emissions of the activators. The energy transfers from Ce3+ to Tb3+ and Dy3+ ions have been found and demonstrated through the PL spectra and luminescence decay times. The emission color of Y4Si2N2O7:Ce3+, Tb3+ and Y4Si2N2O7:Ce3+, Dy3+ samples can be tuned by energy transfer processes. Additionally, the temperature‐dependent PL properties and the degradation property of CL under continuous electron bombardment of the as‐synthesized phosphors prove that the Y4Si2N2O7 host has good stability. Therefore, the Y4Si2N2O7:Ce3+, Tb3+, Dy3+ phosphors could serve as a promising candidate for UV W‐LEDs and FEDs.

Extra-Broad Band Orange-Emitting Ce3+-Doped Y3Si5N9O Phosphor for Solid-State Lighting: Electronic, Crystal Structures and Luminescence Properties

“…In this paper, the two activation energies for the thermal quenching of Y 2.9 Si 5 N 9 O:Ce 0.1 sample match well with two quenching mechanisms. As presented above, the Stokes shift of Ce1 (3123 cm -1 ) and Ce2 (1838 cm -1 ) in Y 3 Si 5 N 9 O host is comparable to that of Y 4 Si 2 N 2 O 7 :Ce blue phosphor (3184cm -1 ) which has a high thermal quenching with the activation energy of about 0.203 eV 24 . Thus, for the title Ce 3+ -doped Y 3 Si 5 N 9 O, the Stokes shift should not be a major reason for the serious thermal quenching.…”

“…[23][24][25] The Ce 3+ -doped Y 3 Si 5 N 9 O in this paper can emit 620 nm orange light ( Figure 7a and b), which makes it more close to that of nitride phosphors in Y-Si-N ternary system. In order to understand this phenomenon, the structure information and measured emission wavelengths of Y-oxonitridosilicate and Y-nitridosilicate phosphors are summarized in Table 3.…”

“…a few ten nanoseconds, as reported in those Ce doped Y-oxonitridosilicate phosphors. [23][24][25] The Ce 3+ in Y 3 Si 5 N 9 O host exhibits smaller decay times than those usual values, and this can be ascribed to the easier non-radiative relaxation in energy transition process. The following analysis on thermal quenching properties will give clear evidence about this hypothesis.…”

K2Ln(PO4)(WO4):Tb3+,Eu3+ (Ln = Y, Gd and Lu) phosphors: highly efficient pure red and tuneable emission for white light-emitting diodes

“…[1][2][3][4][5][6][7] Currently, the commercialized WLEDs fabricated by a blue LED chip with a yellow phosphor, Y 3 Al 5 O 12 :Ce 3+ , suffer a low colourrendering index (CRI) and a high correlated colour temperature (CCT). [8][9][10][11][12][13] Therefore, another approach was suggested to generate white light with a combination of near-ultraviolet (NUV) light and red/green/blue (RGB) primary colour-phosphors such as NaBaBO 3 :Ce 3+ , a broad band green-emitting phosphor with a quantum efficiency (QE) of 58%, 14 Na 2 Y 2 B 2 -O 7 :Ce 3+ ,Tb 3+ , which generates a narrow line green emission with a QE of 75.2%, 15 Na x Ca 1Àx Al 2Àx Si 2+x O 8 :Eu 2+ , a blue phosphor with an external QE exceeding the commercial phosphor, BaMgAl 10 O 17 :Eu 2+ , Mn 2+ , 16 and Ca 4 (PO 4 )O:Eu 2+ , an efficient red phosphor. 17 Nevertheless, the luminous efficiency of the broad band red emission is reduced due to the insensitivity of the human eye at wavelengths close to the near infrared region.…”

Synthesis of mono-phase La 2 Si 6 O 3 N 8 :Ce 3+ ,Tb 3+ blue-green phosphors with direct silicon nitridation and their photoluminescence properties

“…8 is that there was an overlap between the emission band of Ce 3+ and the f-f absorptions of Tb 3+ , which suggests a possible resonance-type energy transfer from Ce 3+ to Tb 3+ in the La2Si6O3N8 host [22,23]. This suggests that Ce 3+ ions can be co-doped as sensitizers to transfer excitation energy to Tb 3+ ions [24][25][26]. The energy levels in Fig.…”