Yellow Phosphor Research Articles

PMMA-Au@YAG:Ce phosphor deposited on flexible substrate for white light emitting devices

This paper investigates the possibility to obtain yttrium aluminum garnet doped with cerium ions (YAG:Ce) phosphor, improve the emissive properties by modification with metal nanoparticles, followed by embedding into the polymer matrix, and deposition of nanocomposite on a flexible substrate to produce the white light by excitation with a blue chip. YAG:Ce yellow phosphor was obtained by a modified solid-state process, followed by in-situ anchoring of gold nanoparticles (Au@YAG). To deposit the phosphor on the flexible substrate, the Au@YAG nanocomposite was embedded in a poly(methyl methacrylate) (PMMA) matrix using the ex-situ method. The quality of the phosphor particles and composites was studied using FTIR spectroscopy, X-ray diffraction, and fluorescence spectroscopy. The applicability of the developed materials and the efficiency of methods were confirmed by the photometric studies performed on the composite film to determine the chromaticity coordinates, leading to the parameters of the semiconductor device that generates cold white light.

Thermal stable and bright yellow-emitting phosphor Na3+xK1-x(AlSiO4)4:Eu2+ for solid-state lighting

High-performance phosphors are essential for phosphor-converted white light-emitting diodes (pc-LEDs) utilized in general lighting applications. This paper introduces Eu2+-activated nepheline solid-solution yellow phosphors Na2.95+xK1-x(AlSiO4)4:0.05Eu2+ exhibiting excellent luminescent properties. All samples demonstrate an emission band at approximately 530 nm. However, the emission intensity gradually increases with higher Na+ content, progressing from Na2.95K(AlSiO4)4:0.05Eu2+ to Na3.95(AlSiO4)4:0.05Eu2+. Correspondingly, the external quantum efficiency (EQE) significantly rises from 41% to 60%. This enhancement in EQE is attribute to the improved absorption efficiency resulting from increased crystallinity. Notably, the emission intensity of representative phosphors at 150 °C remains above 90% of room temperature values, indicating excellent thermal stability. A white pc-LED with a color-rendering index exceeding 85 is successfully developed using the phosphor with the highest EQE. These findings indicate that Na2.95+xK1-x(AlSiO4)4:0.05Eu2+ phosphors show promise as potential candidates for pc-LEDs in general lighting applications.

Realizing Near-Unity Photoluminescence Efficiency in Antimony-Doped Indium-Based Halides Induced by Strong Electron-Phonon Coupling.

Exploring a zero-dimensional (0D) hybrid halide with a large Stokes shift and efficient broad-band emission is highly desirable due to its enormous potential for solid-state lighting (SSL) application. However, it is still challenging to develop a highly emissive 0D hybrid halide with low toxicity and remarkable stability. Herein, we developed a novel indium-based metal halide A5In2Cl16·4H2O (A = doubly protonated 1,4-diaminobutane) whose inorganic octahedrons are completely isolated by the organic cations to form the 0D structure. Experimental and theoretical studies confirmed that Sb-doped A5In2Cl16·4H2O exhibits broad yellow emission with a photoluminescence quantum yield (PLQY) of up to 98%. The intense yellow emission can be attributed to the radiative recombination of triplet self-trapped excitons (STEs) in [SbCl6]3- octahedrons caused by the strong electron-phonon coupling. Benefiting from the excellent stability and photoluminescence performance, A5In2Cl16·4H2O:15%Sb was used as the yellow phosphor to prepare a white-light-emitting diode (WLED) device with a color rendering index of 87.8 and a luminous efficiency of up to 36.18 lm/W, demonstrating its potential in SSL applications. This work provides a guidance for developing environmentally friendly, efficient, and stable ultraviolet (UV)-excited broad-band emission materials.

Novel narrowband emitting red phosphor Sr3La2W2O12:Eu3+ with excellent thermal stability for WLEDs

AbstractThe development of red phosphors with good thermal stability, high quantum yield and high color purity is still a big challenge. In this work, a series of novel red phosphors Sr3La2W2O12:xEu3+ (0≤x≤0.18, ∆x = 0.03) were successfully prepared by high‐temperature solid‐phase method. The phosphors reveal a hexagonal phase with the space group of R‐3 m. The phosphor Sr3La2W2O12:Eu3+ produced narrowband red emission from 5D0→7F2 of Eu3+ (616 nm) under excitation at 395 nm, 465 nm, and 533 nm. Importantly, phosphor Sr3La2W2O12:0.09Eu3+ exhibits astonishing quantum efficiency (IQE = 89.60%, EQE = 41.52%), and it demonstrate robust thermal performance with the emission intensity retaining 92.73% at 558 K of that at 298 K. Finally, the prepared red phosphor Sr3La2W2O12:0.09Eu3+ and yellow phosphor YAG:Ce3+ were combined with a blue LED chip (460 nm) to form a WLED device, which presented warm white light with color coordinates of (0.3523, 0.3732), color rendering index of 83.7, and color temperature of 4826 K.

Full-Visible-Spectrum White LEDs Enabled by a Blue-Light-Excitable Cyan Phosphor.

Efficient blue-light-excitable broadband cyan-emitting phosphors may yield full-visible-spectrum white light-emitting diodes (WLEDs) with ultrahigh color rendering (Ra > 95). However, this requires closing the "cyan gap" in the 480-520 nm region of the visible spectrum, which is challenging. Herein, a well-performed cyan-emitting garnet phosphor Ca2LuAlGa2Si2O12:Ce3+ (CLAGSO:Ce3+) is reported. Under 430 nm excitation, the optimal CLAGSO:5%Ce3+ compound exhibits a broadband cyan emission (peak, 496 nm; bandwidth, 102 nm) with a high internal quantum efficiency of 85.6% and an excellent thermal resistance performance (69.1% at 423 K). Importantly, this as-prepared cyan-emitting phosphor provides sufficient cyan emission and enables filling the well-known so-called "cyan gap" between the blue LED chip and the commercial Y3Al5O12:Ce3+ (YAG:Ce3+) yellow phosphor. Impressively, a WLED device fabricated with the optimal CLAGSO:5%Ce3+ sample shows a low correlated color temperature (4053 K) and an ultrahigh color rendering index (Ra = 96.6), as well as an excellent luminous efficacy (74.09 lm W-1). These results highlight the importance of blue-excited broadband cyan-emitting phosphors in closing the cyan gap and enabling human-centric full-visible-spectrum warm WLED devices for high-quality solid-state lighting.

High thermally stable and efficient rare-earth celsian by phase transformation of Ba2+-Exchanged SOD zeolite

The white LEDs with high performance and excellent luminous quality is of high importance for developing the current lighting industry, and high thermally stable blue phosphors play a critical role in the preparation of white LEDs. Herein, we reported a facile way to obtain highly efficient blue Eu2+-doped celsian phosphor with excellent thermal stability by a phase transformation of Ba2+-exchanged SOD Zeolite strategy. The structure of phosphors changed from nepheline to celsian with the doping of Ba2+, and the maximum emission intensity blue-shifts from 550 nm to 450 nm under the excitation of 370 nm. The PLQY is determined to be 56 %, 96 % and 82 % for the phosphor with Ba2+ doping concentration being 0, 1.49 and 1.86, respectively, and the luminescence intensity at 423 K is can be 80 %, 102 % and 93 % of its intensity at room temperature. Finally, the package of the LED device based on our yellow and blue phosphors together with the commercial red CaAlSiN3:Eu2+ phosphor is constructed to show warm white light with the CCT of 3705 K and a high CRI of 97.7. This study provides a facile way for obtaining satisfactory phosphors for high-quality lighting.

Thermal stable NaMgLaTeO6:Dy3+ double perovskite yellow phosphors for w-LEDs and latent fingerprint visualization

The novel Dy3+-doped NaMgLaTeO6 (NaMgLaTeO6:Dy3+) phosphors were produced through a high-temperature solid-state reaction. X-ray diffraction (XRD) analysis and Rietveld refinement manifest that the pure phosphor was committed to the space group (P21/m (11)) and features the double perovskite structure. The band gap (Eg) of the direct semiconductor NaMgLaTeO6 is calculated to be 2.065 eV. Under 388 nm excitation, the 4F9/2→6H13/2 energy level transition contributes to the maximum emission peak at 572 nm. Other properties of the phosphor include optimal concentration (x = 5 mol %), high thermal stability, activation energy (Ea = 0.31 eV), and internal quantum efficiency (IQE = 31.44 %). The relevant color coordinate of the white light emitting diode (w-LED) prepared by the phosphor is (0.298, 0.311). The features of the latent fingerprint (LFP) created by NaMgLaTeO6:Dy3+ can be clearly reflected on different surfaces. In summary, NaMgLaTeO6:Dy3+ phosphor has proven high potential in w-LEDs production and LFP detection.

Zero-dimensional hybrid Cu(I) halide with cyan light emission for use in white light emitting diode

Traditional white light-emitting diode (WLED) is mainly depending on coating broadband yellow phosphors (520–700 nm) on blue emitting LED chip (440–460). However, too strong blue light and absence of cyan light results in incongruous emission strength and low color rendering index (CRI), which cause serious damage to retina of eye. To overcome these shortcomings, cyan light emitting phosphor is highly desirable for the full-visible-spectrum LED with high CRI, but bright cyan phosphor remains rare. Herein, a new 0D hybrid copper(I) halide of [TMPDA]Cu2I6 (TMPDA = N,N,2,2-tetramethyl-1,3-propylenediamine) single crystal is reported as a cyan light emitter with mominant emission wavelength at 489 nm, photoluminescence quantum yield of 26.66 % and large Stokes shift of 198 nm exceeding most of organic-inorganic metal halides. Remarkably, the single crystals display stable emission in various polar organic solvents and high temperature with sufficient emitting stability. More significantly, this 0D cuprous halide act as down-conversion cyan phosphor to fabricate WLED with a high CRI of 95 by reducing the cyan gap. In this study, we demonstrate an optical engineering strategy to prepare efficient cyan light emitting 0D cuprous halide and assembly high-performance WLED.

Electronic defect engineering of double-doped β-KYF4:Eu3+,Bi3+ red phosphors: Negative thermal quenching and applications for high-efficiency white light-emitting diodes

Commercial WLEDs in a cold white light with a lower color rendering index(Ra) and higher correlated color temperature due to the lack of a red component. Therefore, we propose to develop a non-oxide rare-earth-based red phosphor with excellent luminescence performance and thermal stability. The crystal phases, particle morphology, elemental states, photoluminescence(PL) behavior, and electronic structure were characterized. The Density Functional Theory (DFT) calculation was carried out to reveal the mechanisms of the crystal and electronic structures on the photoluminescent properties and the associated energy-transfer mechanisms. Furthermore, the optimal double-doped KYF4 phosphor with negative thermal quenching and the yellow phosphor YAG:Ce3+ were co-assembled into LEDs, which exhibited a warm white light with a color rendering index of 93.9 and a correlated color temperature of 4275 K under a driving current of 9 mA. These results indicate that the optimized phosphor has considerable potential for application in red light supplements for WLEDs.

A novel Mn4+-doped Li2Mg4TiO7 red-emitting phosphor for warm white light-emitting diodes

To improve the light quality of warm white-LEDs (w-LEDs), novel Mn4+-activated red-emitting phosphors that can be excited efficiently by blue light with yield high performance are highly imperative. Here, we report a Mn4+-doped Li2Mg4TiO7 (LMT) phosphor prepared via a traditional high-temperature reaction method. The crystal structure and luminescent properties of the LMT:Mn4+ phosphors are studied. An excitation band centered at 470 nm, matches well with the commercial blue LED chips. Upon blue light excitation, a broadband red emssion located at 673 nm due to d-d transitions of Mn4+ is observed. The optimum doping concentration of Mn4+ is determined to be x = 0.08 %. The optimized red-emitting phosphor LMT:Mn4+ attains a photoluminescence quantum yield (PLQY) of 40.0 % and a good thermal resistance (ΔE = 0.43 eV). The combination of the as-obtained red-emitting phosphor, commercially available yellow phosphor, and blue LED chip yields a warm w-LED device, delivering CIE (x, y) = (0.3922, 0.3909), CRI = 70.0 and CCT = 2214 K. Therefore, this work provides a novel LMT:Mn4+ phosphor as a potential red component for warm w-LEDs.

Impacts of Eu2+ -doped K3LuSi2O7 phosphor and a scattering particle on conventional white light emitting diodes

The K<sub>3</sub>LuSi<sub>2</sub>O<sub>7</sub> phosphor doping Eu2+ rare-earth ions (KLS:Eu) was reported to possess broad emission band from near-ultraviolet to nearinfrared. Additionally, this phosphor showed a wide absorption band of 250-600 nm, allowing it to be excited by blue-light chip of 460 nm, making it one of the suitable phosphor materials for a light emitting diode (LED). Besides, the scattering particle material CaCO<sub>3</sub> is incorporated into the yellow phosphor layer to serve the scattering-enhancement purpose. The combination of both materials aims at accomplishing improvements in performance of commercial LED package. The concentration of KLS:Eu is constant while that of CaCO3 is modified. As a result, the scattering factor is regulated and become the key factor influencing the optical outputs of the simulated LED. The increasing CaCO<sub>3</sub> concentration enhances the phosphor scattering efficiency of light, helping to improve the lumen output and color-temperature consistency of the LED. However, the color rendering performance declines as a function of the CaCO3 growing amount, despite the presence of a KLS:Eu phosphor layer. Further works should be done to optimize the application of KLS:Eu in cooperation with scattering particles for a higher-quality LED device.

Preparation and properties of CsMoO2F3:Mn4+ red phosphor with anti-thermal quenching and high color rendering index

The CsMoO2F3:Mn4+ red phosphors were prepared by the lower coprecipitation method. The XRD data of the powder were refined by Rietveld using GSAS software. The crystal structure of the powder was orthogonal structure, and the space group was Imma. The strongest excitation band of the sample was located at 468 nm and the strongest emission band at 633 nm. When the Mn4+ doping ratio was 11 %, the CsMoO2F3:Mn4+ red phosphor had the strongest luminescence intensity with a color purity of 99.25 %. CsMoO2F3:Mn4+ red phosphor mixed with commercial YAG:Ce3+ yellow phosphor was coated on a blue LED chip and encapsulated into a white LED. The resulting device at a drive current of 50 mA had a 95.0 color rendering index and a correlated color temperature of 4320 K, with a radiant luminous efficacy of 356.3 lm/W. CsMoO2F3:Mn4+ red phosphor had better thermal stability than the previous Mn4+-doped fluorine oxide phosphors. At 423 K, the luminous intensity at this time was 117 % of that at room temperature (303 K), with excellent heat resistance.

Preparation and properties of tellurite glass-based CsPb(BrCl)3@glass fluorescent film for a white light emitting diode color converter

Perovskite nanocrystal glass has the advantages of narrow-band emission, easy tuning, and stable structural, physical, and chemical properties, and can be used to mix with other colored materials for white light modulation. The current white light mode widely adopts the packaging method of blue light chip and yellow phosphor, which has the problem of a blue-yellow cavity and low light quality. In this work, the central wavelength of CsPb(BrCl)3 can be adjusted continuously ranging from 463 nm to 486 nm by adjusting the relative ratio of bromine to chlorine in nanocrystals. On the basis of the previous design of YAG:Ce phosphor-in-glass, perovskite nanocrystal glass powder as a color compensator was introduced into the tellurite glass matrix to form a doubly encapsulated system by low-temperature co-sintering. The yellow phosphor and perovskite nanocrystal glass maintain good structural integrity in the glass matrix. By combining the double-package fluorescent material with the blue chip, the continuous adjustment of chromaticity coordinates along the saddle line is realized, and the color-rendering index is also improved to 81.3.

Bismuth (Bi3+) and Tellurium (Te4+) doped Cs2ZrCl6 lead-free halide perovskite phosphors for white LEDs

Lead-free halide double-perovskite materials have been given extensive attention due to the charming fluorescent property and simple synthesis process. Their strong electro-acoustic coupling effects endow the materials with wideband emission properties and the tremendous potential application in white light emitting diodes (w-LEDs). Herein, the blue (456 nm) and yellow (578 nm) light emitting phosphors with broad band emission were synthesized by introducing the Bi3+ and Te4+ into the structure-stable and low toxicity Cs2ZrCl6 materials, respectively. The blue and yellow emission from 3P1 → 1S0 transitions of Bi3+ and Te4+ were achieved in Cs2ZrCl6: 7%Bi3+ and Cs2ZrCl6: 3%Te4+, where the large full width at half maximum (FWHM) values of 45 and 101 nm were attributed to the large Huang-Rhys factor and electro-acoustic coupling strength. The white LED fabricated through combining the 365 nm chip with the prepared blue and yellow phosphors exhibited wideband white light emission ranging from the 400–750 nm with correlated color temperature (CCT) 5028 K and good color rendering index (CRI) 84.

Strategically Developed Strong Red‐Emitting Oxyfluoride Nanophosphors for Next‐Generation Lighting Applications

AbstractRed‐emitting nanophosphors have a multirole in improvising the next‐generation bulk/micro/nano‐level lighting devices, particularly in refining white light quality and device performance. Nonetheless, it is difficult to synthesize nanosized phosphors with good yield and paralleled high absorption efficiency both in UV and blue regions, which is critical for modern lighting. Herein, new Mg14Ge4.99+σO24‐x+δFx: Mn4+ red nanoparticles with sizes below 100 nm are designed to improve not only the luminescence but also the blue light absorption. This approach has validated the applicability of red‐emitting nanophosphors into flexible UV and blue nitride nanowire light‐emitting‐diodes (LEDs), and commercial bulk LEDs, for the first time, with boosted intensity and color superiority for a variety of lighting utilizations. For these phosphor LEDs (pc‐LEDs), optimized red nanophosphor with an external quantum efficiency of ≈44.5%, color purity of ≈100%, and thermal stability of ≈72% at 150 °C is used. The optimized nanophosphor is combined with a flexible UV‐AlGaN/GaN nanowire LED and a blue‐InGaN/GaN‐LED. The resultant devices show promising red electroluminescence without any degradation at elevated currents. Finally, several unfamiliar LED packaging is designed with yellow and red phosphors implemented on 2 sets of double LED units to reach CRI > 85. The re‐premeditated LED packages are useful for high‐definition lighting.

Antimony doping towards fast digital encryption and decryption and high-efficiency WLED in zero-dimensional hybrid indium chlorides

Lead-free metal halides with thermally induced reversible fluorescence transitions are promising smart optoelectronic materials. However, it is challenging to obtain such materials with reversible and fast fluorescent thermochromism at relatively low temperatures. Herein, two series of new zero-dimensional (0-D) hybrid perovskite indium chlorides doped with Sb3+ are synthesized and characterized, namely (TAEA)InCl6·Cl·4H2O: xSb3+ (1: xSb3+) and (TETA)InCl6·Cl·H2O: xSb3+ (2: xSb3+) (TAEA = quadruply protonated tris(aminoethyl)amine; TETA = quadruply protonated triethylenetetramine; x = 0 − 15 %). Compound 1: 0.5 %Sb3+ displays green broadband emission with photoluminescence quantum yield (PLQY) of 44.4 %, while compound 2: 1 %Sb3+ produces yellow emission with PLQY of 73.46 %. A reversible transition between green and orange light emission for 1: 0.5 %Sb3+ can be triggered by thermal stimulation; such photoluminescence (PL) color switching happens with a fast response time of 20 s and a low transition temperature of 333 K. In addition, the materials combining compounds 2: 1 %Sb3+ and 1: 0.5 %Sb3+ can achieve complex digital encryption and decryption upon heating. Furthermore, due to its excellent luminous efficiency, the 2: 1 %Sb3+ is employed as yellow phosphor for white light-emitting diode (WLED). The WLED shows a CRI of 90.5 and a CCT of 5415 K, superior to most WLEDs based on hybrid metal halides. Finally, the impact of forming the self-trapped excitons state and complex PL mechanism of compound 1: 0.5 %Sb3+ are investigated through DFT calculations and femtosecond transient absorption techniques. This work provides new insights into the design of hybrid metal halides with multiple optical properties, paving the way to obtaining materials for multiple optical applications.

Effectively enhanced the luminescent properties and water resistance of K2TaF7: Mn4+ red phosphors by introducing In3+ ions in the matrix and constructing a homogeneous core-shell structure

Shell-free K2Ta1-xInxF7: Mn4+ red phosphor was synthesized by introducing In3+ ions in K2TaF7: Mn4+ with a non-centrosymmetric octahedral structure. The strategy of the heterogeneous substitution of In3+ by Ta5+ further distorted the octahedral structure, effectively enhanced the emission intensity of Mn4+. Its overall luminous intensity was increased to 6.9 times that of K2TaF7: Mn4+. Moreover, the red phosphor with a homogeneous core-shell structure was successfully prepared by using a weak reducing agent citric acid to solve the problem of poor water resistance. After soaking in water for 10 days, the emission intensity of the red phosphor with a homogeneous core-shell structure retained 90% of the initial value. It is the first time to successfully construct a core-shell structure for A2BF7: Mn4+ type fluoride phosphors to effectively improve its water resistance. Mixing it with commercial YAG: Ce3+ yellow phosphor and encapsulating them with a commercial blue chip led to the development of warm white light-emitting diodes (WLEDs) with good qualities. K2Ta1-xInxF7: Mn4+ red phosphor with homogeneous core shell is a novel red phosphor with good luminous performances and excellent water resistance.

Boosting the red emission and luminescent thermostability of GdPO4:Eu3+ phosphors by coating with graphitic carbon nitride

Due to the fact that the luminescence of Eu3+ belongs to orbital forbidden f→f transition, the luminous intensity of Eu3+-activated phosphors is relatively weak. In this work, in order to increase the luminous intensity of GdPO4:Eu3+, a series of GdPO4:Eu3+@g-C3N4 phosphors was obtained via conventional solid-state reaction, with GdPO4:0.05Eu3+@0.005 g-C3N4 identified as the optimal sample. The characterization results indicate that: (a) The coating of g-C3N4 not only enhances the luminescence, but also unexpectedly induces a relatively weak negative thermal quenching (NTQ) effect, thereby obviously improving its luminescence thermal stability. The mechanisms behind the enhanced luminescence and luminescence thermal stability are explored, and attributed energy transfer from g-C3N4 to Eu3+ and phonon electron interaction, respectively. (b) The WLED prepared with GdPO4:0.05Eu3+@0.005 g-C3N4 and yellow fluorescent phosphor (YAG:Ce3+) forms warm-white light under excitation of ultraviolet light. The findings reveal that GdPO4:0.05Eu3+@0.005 g-C3N4 is a potential candidate for using in the field of warm WLEDs excited by ultraviolet light.

Luminescence studies and Judd Ofelt parameterization of Dy3+ activated La2(WO4)3 yellow phosphor

The synthesis and detailed luminescence studies of a series of La2-xDyx(WO4)3 (x = 0.02, 0.1, 0.2, 0.4, 0.6, 0.8) phosphors synthesized via microwave-assisted co-precipitation technique is reported in this paper. The XRD analysis confirmed that the phosphors were crystalized in a monoclinic structure with space group C2/c and FTIR analysis identified the characteristic vibrational modes. Morphological studies were conducted using FESEM analysis, and the EDS technique substantiated the effective incorporation of Dy3+ ions in La2(WO4)3. The photoluminescence excitation and emission spectra of varying concentrations of Dy3+ ions were recorded and an optimum concentration of 10% exhibited the highest intensity. The emission spectra of all phosphors were dominated by peaks at 484 nm and 574 nm. The radiative properties were evaluated using Judd-Ofelt analysis and the JO intensity parameters followed the trend Ω2 > Ω6 > Ω4. The gradual decrease in the decay lifetime value of 4F9/2 excited level with an increase in doping concentration elucidates concentration quenching phenomena due to dipole – quadrupole interaction. The emission data were also analyzed by calculating CIE coordinates and concluded that Dy3+ doped La2(WO4)3 phosphors have potential applications in yellow light generation.

Atomic-level investigation of structure and formation process of Y3Al5O12 with super-high content of Ce emitting anomalous orange-red emissions

Ce-doped yttrium aluminum garnet (YAG:Ce, Y3Al5O12:Ce) is the most commonly used yellow phosphor in white light-emitting diodes. Recently, we found that (Y1–xCex)3Al5O12:Ce with a super-high content of Ce (x = 0.11–0.21) can be prepared by a polymerized complex method and exhibits anomalous orange–red emission. To understand the nature of this anomalous behavior from the atomic level, we applied high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and scanning transmission electron microscopy–energy dispersive X-ray spectroscopy (STEM-EDS), a state-of-the-art technique that enables analysis of the atomic-level elemental distributions of Al, Y, and Ce. STEM-EDS images on the atomic level were successfully obtained for YAG:Ce. It was found that Ce in Y site has spatially uneven for few nanometers. Ce–K edge extended X-ray absorption fine structure (EXAFS) analysis was also conducted, which revealed a high level of asymmetry around Ce. By combining the STEM-EDS and EXAFS results, a dynamic model for the red emission was proposed. STEM-EDS also revealed that CeO2 nanocrystals were firstly formed with low-temperature annealing and that the reaction of Y with the CeO2 nanocrystals subsequently yielded YAG:Ce, unlike in the conventional one-step high-temperature synthesis.