High luminescent brightness and thermal stability of red emitting Li3Ba2Y3(WO4)8:Eu3+ phosphor

A series of Li₃Ba₂Y_3−x(WO₄)₈:xEu³⁺ (x=0.1, 1, 1.5, 2 and 2.8) phosphors were synthesized by a high temperature solid-state reaction method. Under the excitation of near ultraviolet (NUV) light, the as-prepared phosphor exhibits intense red luminescence originating from the characteristic transitions of Eu³⁺ ions, which is 1.8 times as strong as the commercial Y₂O₂S:Eu³⁺ phosphor. The optimal doping concentration of Eu³⁺ ions here is confirmed as x=1.5. The electric dipole-quadrupole (D-Q) interaction is deduced to be responsible for concentration quenching of Eu³⁺ ions in the Li₃Ba₂Y₃(WO₄)₈ phosphor. The analysis of optical transition and Huang-Rhys factor reveals a weak electron-phonon coupling interaction. The temperature-dependent emission spectra also indicate that the as-prepared Li₃Ba₂Y₃(WO₄)₈:Eu³⁺ phosphor has better thermal stability than that of the commercial Y₂O₂S:Eu³⁺ phosphor. Therefore, our results show that the as-prepared Li₃Ba₂Y₃(WO₄)₈:Eu³⁺ phosphor is a promising candidate as red emitting component for white light emitting diodes (LEDs).     

The effects of Mg2+/Si4+ co-substitution for Al3+ on sintering and photoluminescence of (Gd,Lu)3Al5O12:Ce garnet ceramics

A series of phase-pure [(Gd_0.6Lu_0.4)_0.99Ce_0.01]₃[Al_1-z(Mg/Si)_z]₅O₁₂ (z = 0-0.10) garnet phosphor powders were prepared via gel-combustion, which were then sintered into ceramics (up to 1550 °C) under atmospheric pressure. Dilatometry revealed that equimole of Mg²⁺/Si⁴⁺ substitution for Al³⁺ accelerates densification and lowers the activation energy for grain boundary diffusion in the intermediate stage of sintering (∼1150–1370 °C), which was assayed to be ∼353 kJ/mol for z = 0 and ∼289 kJ/mol for z = 0.10. The acceleration effects of Mg²⁺/Si⁴⁺ on sintering and grain growth were further demonstrated by the results of ramp and holding sintering. Firing at 1550 °C for 4 h also produced ∼99 % dense ceramics for the Mg²⁺/Si⁴⁺ codoped garnet powders. Through considering crystal splitting of the Ce³⁺ 5d energy level, photon-phonon coupling, and crystal structure/microstructure, the influences of Mg²⁺/Si⁴⁺ content and material form on Ce³⁺ luminescence, including intensity, external/internal quantum efficiencies, emission wavelength, CIE color coordinates and decay time, were clarified in detail.     

Highly efficient yellow-orange emission and superior thermal stability of Ba2YAl3Si2O12:Ce3+ for high-power solid lighting

With great economic benefits, white LEDs (w-LEDs) have aroused worldwide attention. For phosphor-converted w-LED, highly efficient emission and good thermal stability of phosphor are significant parameters in practical application. Here, a yellow-orange garnet-structural phosphor, Ba₂YAl₃Si₂O₁₂:xCe³⁺ (x = 0-0.1) (BYAS:xCe³⁺) was developed by solid solution design. The broad emission spectrum of the as-synthesized phosphor could guarantee the effective increase of the color rendering index when it is combined with the InGaN blue chip. Benefiting from the garnet-type highly rigid framework, BYAS:xCe³⁺ exhibits an excellent thermal stability (50%@673K of the initial integrated intensity at 280 K) as well as high absolute quantum efficiency (80.4%@460 nm excitation light). Utilizing the approach of “phosphor-in-glass” (PiG), a high-power warm w-LED is achieved based on a blue LED plus PiG and the illuminance of this w-LED device can be as high as 4227 lx.     

White‐emitting phosphor Ba2B2O5:Ce3+, Tb3+, Sm3+: Luminescence,energy transfer,and thermal stability

A series of Ba₂B₂O₅: RE (RE=Ce³⁺/Tb³⁺/Sm³⁺) phosphors were synthesized using high‐temperature solid‐state reaction. The X‐ray diffraction (XRD), luminescent properties, and decay lifetimes are utilized to characterize the properties of the phosphors. The obtained phosphors can emit blue, green, and orange‐red light when single‐doped Ce³⁺, Tb³⁺, and Sm³⁺. The energy can transfer from Ce³⁺ to Tb³⁺ and Tb³⁺ to Sm³⁺ in Ba₂B₂O₅, but not from Ce³⁺ to Sm³⁺ in Ce³⁺ and Sm³⁺ codoped in Ba₂B₂O₅. However, the energy can transfer from Ce³⁺ to Sm³⁺ through the bridge role of Tb³⁺. We obtain white emission based on energy transfer of Ce³⁺→Tb³⁺→Sm³⁺ ions. These results reveal that Ce³⁺/Tb³⁺/Sm³⁺ can interact with each other in Ba₂B₂O₅, and Ba₂B₂O₅ may be a potential candidate host for white‐light‐emitting phosphors.     

Inorganic remote glass film based on yellowish-green (Y,Ba)3(Al,Si)5O12:Ce garnet phosphor for warm white LEDs

Compared with other fluorescent crystal phases, garnet has better structural stability in a glass matrix and renders precisely controllable emissions due to the abundant lattice control positions. In this work, we regulate the coordination field of Ce³⁺ ion based on the co-substitution method and achieve the spectra regulation in the yellow–green range. We used Ba²⁺–Si⁴⁺ cations to replace Y³⁺–Al³⁺ cations in Y₃Al₅O₁₂ (YAG) matrix to obtain blue-shift of the emission peak from 552 to 539 nm. The centroid shift and crystal field splitting decrease with the decreasing covalency of the bond between the Ce³⁺ ion and the surrounding anions owing to the higher electronegativity of Si⁴⁺ ions than Al³⁺ ions. The corresponding fluorescent films were prepared by a low-temperature co-sintering process based on the as-made Ba²⁺–Si⁴⁺ co-substituted phosphor. X-ray powder diffractometer and scanning electron microscopy images showed that the fluorescence crystals were less eroded and evenly dispersed in the glass matrix. Spectral analysis showed that the garnet phase was protected by using lead-free borosilicate glass with a low melting point, and the quantum efficiency of phosphor-in-glass (PiG) retains 98% of the corresponding phosphor. By adjusting the ratio of garnet phosphor to commercial red nitride phosphors, a warm white fluorescence with a color rendering index of 80.3 and color temperature of 3899 K was obtained. The prepared warm white film has potential application value in the whole spectra field.     

Electronic structure and luminescent properties of Ce3+-doped Ba3Lu2B6O15, a high-efficient blue-emitting phosphor

A high-efficient blue-emitting phosphor Ba₃Lu₂B₆O₁₅: Ce³⁺ was synthesized by three-step solid-state method. XRD Rietveld refinement analysis reveals that Ba₃Lu₂B₆O₁₅ is of cubic Ia$3(——)$ system, owning a high-symmetric layer structure with two regular LuO₆ octahedrons and one BaO₉ polyhedron. Density functional theory (DFT) calculation result indicates BLB is a kind of direct band-gap material with broad band-gap of ~5.10?eV. Ba₃Lu₂B₆O₁₅:Ce³⁺ phosphor exhibits a bright blue emission under UV excitation with high quantum efficiency of >?90%, and the possible reasons are discussed basing on structural and spectral data. Because of its excellent luminescent properties, Ba₃Lu₂B₆O₁₅:Ce₃⁺ could be a promising candidate as a blue phosphor for NUV LED devices.     

The effect of Lu3+ doping upon YAG:Ce phosphor ceramics for high-power white LEDs

Intense green emission is extremely significant to the color rendering index (CRI) of white LEDs. Various green-emitting YLuAG:Ce phosphor ceramics were successfully prepared by vacuum sintering. The effects of Lu³⁺ doping on structure and luminescence property were investigated in detail. In comparison with YAG:Ce, YLuAG:Ce ceramics own smaller grain size, better luminescence performance and higher thermal stability. The photoluminescence (PL) intensity of YLuAG:Ce ceramics increases by 23.6 % due to the “light scattering enhanced effect”. Furthermore, the Ce³⁺ emission is obviously blue-shifting from 533 nm to 519 nm, and the intensity of YLuAG:Ce ceramics reduces only about 8.9 % at 250 °C, showing better thermal stability (vs 11.1 % of YAG:Ce). The LE of LED packaged by YLuAG:Ce ceramic is up to 148.88 lm/W when the doping Lu³⁺ y is 2.1. The above results show that tailored YLuAG:Ce phosphor ceramic is a potential green-emitting color converter for high-power LEDs (hp-LEDs).     

Effect of Ga3+ ion doping on emission thermal stability and efficiency of MgAl2O4:Cr3+ phosphor

In this work, we fabricated a novel spinel-type phosphor material MgAl_2−xGa_xO₄ doped with Cr³⁺ by the high-temperature solid-state sintering method. The crystal field environment of the spinel was tuned by replacing the Al ions with Ga³⁺ ions of different concentrations. The cell volume and D_q/B gradient increase from 2.82 to 2.62 with increasing Ga³⁺ ion doping concentration. This also implies a gradual decrease in the field strength of the crystal. Based on this, the excitation spectra of MgAl_1.995−xGa_xO₄:0.5%Cr³⁺ phosphors yield a redshift. Increasing the Ga³⁺ ion doping concentration also improves the emission intensity and thermal stability of the phosphors, and the emission intensity of the Ga³⁺-doped phosphors is significantly increased. For a Ga/Al ratio of 1, the thermal stability of the phosphor emission is optimal. The emission intensity at 140°C can maintain 76% of the emission intensity at room temperature, indicating that appropriate Ga³⁺ ion doping can improve the emission efficiency and thermal stability of the phosphors.     

Luminescence properties of Ca2GdNbO6: Sm3+, Eu3+ red phosphors with high quantum yield and excellent thermal stability for WLEDs

A series of Ca₂GdNbO₆: xSm³⁺ (0.01 ≤ x ≤ 0.15) and Ca₂GdNbO₆: 0.03Sm³⁺, yEu³⁺ (0.05 ≤ y ≤ 0.3) phosphors were synthesized by the traditional solid-state sintering process. XRD and the corresponding refinement results indicate that both Sm³⁺ and Eu³⁺ ions are doped successfully into the lattice of Ca₂GdNbO₆. The micro-morphology shows that the elements of Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphor are evenly distributed in the sample, and the particle size is about 2 μm. The optical properties and fluorescence lifetime of Ca₂GdNbO₆: 0.03Sm³⁺, Eu³⁺ phosphors were detailedly studied. The emission peak at ⁵D₀→⁷F₂ (614 nm) is the strongest and emits red light under 406 nm excitation. The increase of Eu³⁺ concentration causes the energy transfers from Sm³⁺ to Eu³⁺ ions, and the transfer efficiency reaches 28.6%. Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphor has a quantum yield of about 82.7%, and thermal quenching activation energy is of 0.312 eV. The color coordinate (0.646, 0.352) of Ca₂GdNbO₆: 0.03Sm³⁺, 0.2Eu³⁺ phosphors is located in the red area. The LED device fabricated based on the above phosphor emit bright white light, and CCT = 5400 K, Ra = 92.8. The results present that Ca₂GdNbO₆: 0.03Sm³⁺, Eu³⁺ phosphors potentially find use in the future.     

Sr-induced color-tunable and thermal stability enhancing in the phosphor (Ba1-xSrx)9Lu2Si6O24:Eu2+ for solid-state lighting

Rare earth ions’ site occupation is significant for studying luminescence properties by changing the host composition. The (Ba_1-xSr_x)₉Lu₂Si₆O₂₄:Eu²⁺ (x = 0-0.4) tunable-color phosphors were synthesized via a high temperature solid-state reaction. With the Sr²⁺ ions concentration increase, the luminescent color could be tuned from blue to green. This phenomenon is discussed in detail through the ions occupation in the host lattice. More importantly, the temperature-dependent luminescence of (Ba_1-xSr_x)₉Lu₂Si₆O₂₄:Eu²⁺ phosphors was investigated and exhibited excellent thermal stability. Furthermore, white LED device has been fabricated using (Ba_1-xSr_x)₉Lu₂Si₆O₂₄:Eu²⁺ phosphor mixed with commercial red phosphor Sr₂Si₅N₈:Eu³⁺ combined with a 370 nm UV-chip. This device showed correlated color temperature (CCT) of 5125 K and high color render index (CRI) of 91. This phosphor will be a promising candidate as a tunable-color phosphor for UV-based white LEDs.     

Red-emitting enhancement of Bi4Si3O12:Sm3+ phosphor by Pr3+ co-doping for White LEDs application

In this account, Bi₄Si₃O₁₂:Sm³⁺ and (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) red phosphors were prepared by solution combustion method fueled by citric acid at 900 °C for 1 h. The effects of co-doping Pr³⁺ ions on red emission properties of Bi₄Si₃O₁₂:Sm³⁺ phosphors, as well as the mechanism of interaction between Sm³⁺ and Pr³⁺ ions were investigated by various methods. X-ray diffraction (XRD) and Scanning electron microscopy (SEM) revealed that smaller amounts of doped rare earth ions did not change the crystal structure and particle morphology of the phosphors. The photoluminescence spectroscopy (PL) indicated that shape and position of the emission peaks of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at λ_ex=403 nm were similar to those of Bi₄Si₃O₁₂:Sm³⁺ phosphors. The strongest emission peak was recorded at 607 nm, which was attributed to the ⁴G_5/2→⁶H_7/2 transition of the Sm³⁺ ion. The photoluminescence intensities of Bi₄Si₃O₁₂:Sm³⁺ phosphors were significantly improved by co-doping with Pr³⁺ ions and were maximized at Sm³⁺ and Pr³⁺ ions doping concentrations of 4 mol% and 0.1 mol%, respectively. The characteristic peaks of Sm³⁺ ions were displayed in the emission spectra of (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors excited at respectively λ_ex=443 nm and λ_ex=481 nm (Pr:³H₄→³P₂, ³H₄→³P₀). This indicated the existence of Pr³⁺→Sm³⁺ energy transfer in (Bi₄Si₃O₁₂:Sm³⁺, Pr³⁺) phosphors.     

A novel red-emitting Na5W3O9F5:Eu3+ phosphor with high color purity for blue-based WLEDs

Red phosphor plays a key role in improving the lighting and display quality of phosphor-converted white light-emitting diodes (pc-WLEDs). Meanwhile, developing new luminescent matrix materials can positively contribute to the acquisition of ideal and efficient phosphors. In this work, we propose a novel red-emitting Na₅W₃O₉F₅:Eu³⁺ (NWOF:Eu³⁺) phosphor. The phase composition, morphology, electronic structure and photoluminescence properties of the NWOF:Eu³⁺ phosphor were systematically investigated. The EXAFS results prove that the Eu³⁺ dopants occupy the Na2 and Na3 sites in the NWOF host. Under 466 nm blue light excitation, NWOF:xEu³⁺ (0.05 ≤ x ≤ 0.25) phosphors display a dominant red emission at 607 nm and achieves a high color purity (97.44%) due to the dominant electric dipole transition (⁵D₀→⁷F₂) of Eu³⁺ ions. Impressively, this red-emitting NWOF:0.25Eu³⁺ phosphor exhibits relatively superior thermal stability (450 K, >50%) and excellent chromaticity stability (2.32 × 10^?4 ≤ ΔE ≤ 6.23 × 10^?3) from 298 K to 498 K. The activation energy for thermal quenching effect is determined to be 0.22 eV. Moreover, the pc-WLED was fabricated by coupling a 460 nm blue chip with the as-synthesized NWOF:0.25Eu³⁺ red phosphor and commercial YAG:Ce³⁺ phosphor. The optical parameters of the as-fabricated pc-WLED are also measured, and the CIE coordinates remain almost constant as the drive current increases from 20 mA to 120 mA. These results indicate that the NWOF:0.25Eu³⁺ red phosphors should be a suitable candidate as a red component for the preparation of pc-WLEDs.     

Apatite oxynitride phosphor (Mg,Y)5Si3(O,N)13:Ce3+,Mn2+: A single-phased host with solar-like and efficient emission

During pursuing high color rendering index for full-color-emitting phosphor, low quantum efficiency (QE) is usually accompanying. We intend to elevate the luminescence efficiency when realizing a solar-like spectra distribution, by constructing apatite structure oxynitride, inheriting high covalence and rigidity from oxynitride, and suitable multiple cation sites from oxyapatite compounds. Full-color-emitting apatite structure oxynitride phosphor (Mg,Y)₅Si₃(O,N)₁₃:Ce³⁺,Mn²⁺ has been prepared, and the crystal sites’ occupancies of activators in this host were favorable for white emission. (Mg,Y)₅Si₃(O,N)₁₃:Ce³⁺,Mn²⁺ phosphor shows whole visible light with emission wavelength ranging from 370 to 750 nm, matching the spectra of sunlight quite well. The fabricated white light-emitting diode lamp demonstrated the distinctive overall performance of QE and chromaticity properties (R_a and R₉). Furthermore, correlated color temperature is tunable from cool nature to warm white. The obtained lamp possesses the feature of less blue light hazard and high saturation of red degree, compared with the commercial YAG-based lamp.     

A low cost and high efficient Ba9(Lu2-x-yAlx)Si6O24:yCe3+ cyan-emitting phosphor

White LEDs constructed by near-ultraviolet chips and red/green/blue/cyan-emitting phosphors are an important route for healthy lighting. However, efficient cyan-emitting phosphors are quite scarcity. The cyan-emitting phosphor Ba₉Lu_1.5Al_0.5Si₆O₂₄:Ce³⁺ (BLASO:Ce³⁺) was reported for the first time. Under 400 nm excitation, BLASO:Ce³⁺ shows a emission peak at 488 nm with an FWHM of about 117 nm. At room temperature, the internal quantum efficiency (IQE) can reach as high as 90.8%. At 150 °C, the IQE decreases to 81.5%, indicating an excellent thermal stability. The effect of the Al substitution for Lu on crystal structures and photoluminescence were investigated. The homogeneity of the luminescence was diagnosed by viewing microscopic particles based on the scanning electron microscope (SEM) equipped a cathodoluminescence (CL) system.     

Erosion behavior and luminescence properties of Y3Al5O12:Ce3+-embedded calcium bismuth borate glass-ceramics for WLEDs

Current white light emitting diodes (WLEDs) have poor thermal stability and lack red-light, which restrict their applications in high-power and high-color-rendering-index solid-state lighting. YAG glass-ceramics provide an efficient way to resolve these problems. Herein, novel YAG-embedded calcium bismuth borate glass-ceramics (YAG-GCs) with Eu³⁺ doping were prepared using a rapid melt quenching technique. The precursor glass exhibits superior YAG refractive index matching and high transmittance. Differential scanning calorimeter simulations verify YAG particles react with the precursor glass. The degree of YAG erosion is slight but monotonously increases with the co-sintering temperature from 640 to 700°C. The erosion products probably contain YAB (Al₃Y(BO₃)₄), Al₃Eu(BO₃)₄, Bi₂₄B₂O₃₉, and Ca₁₂Al₁₄O₃₃ phases, and the Bi ion valence state is maintained during the reaction process. The energy transfer from Ce³⁺ to Eu³⁺ is suppressed. The YAG-GC PL intensities monotonously increase as the co-sintering temperature decrease from 640 to 700°C and the YAG content increase from 2.5 to 7 wt.%. The optical parameters of a WLEDs packed by YAG-GCs and blue chips are a luminous efficiency of 105.3 lm/W, correlated color temperature of 3940 K and color rendering index of 70.1. The as-prepared YAG-GCs are promising candidates for high-power, warm WLEDs due to their superior thermal stability, high quantum efficiency, and low cost.     

Design of a narrow-band blue-emitting Rb2Ba3(P2O7)2:Eu2+ phosphor with low thermal quenching for plant growth LEDs

Phosphor-converted light-emitting diodes (pc-LEDs) are commonly used to regulate the light environment to control the growth rates and improve the production efficiency of plant. Among them, the exploration of blue-emitting phosphors with high efficiency, low thermal quenching and excellent spectrum resemblance matching with the plant response spectrum is still challenging. Herein, a narrow-band blue-emitting Rb₂Ba₃(P₂O₇)₂:Eu²⁺ phosphor with high color purity of 93.4% has been developed. Under 345 nm excitation, it exhibits a blue emission band centered at 413 nm with a full width at half-maximum (FWHM) of 36 nm, and the emission spectrum of Rb₂Ba₃(P₂O₇)₂:0.060Eu²⁺ sample shows 85.7% spectrum resemblance with the absorption spectrum of chlorophyll-a in the blue region from 400 to 500 nm. In addition, the temperature-dependent emission spectra demonstrate that the Rb₂Ba₃(P₂O₇)₂:0.060Eu²⁺ phosphor has good thermal stability and small chromaticity shift, with the emission intensity dropping to 72.5% at 423 K of the initial intensity at 298 K and a chromaticity shift of 38 × 10^-3 at 498 K. All results suggest that the blue-emitting Rb₂Ba₃(P₂O₇)₂:Eu²⁺ phosphor has potential application in plant growth LEDs.     

Dual effect synergistically triggered Ce:(Y,Tb)3(Al,Mn)5O12 transparent ceramics enabling a high color-rendering index and excellent thermal stability for white LEDs

Ce:Y₃Al₅O₁₂ transparent ceramics (TCs) with appropriate emission light proportion and high thermal stability are significant to construct white light emitting diode devices with excellent chromaticity parameters. In this work, strategies of controlling crystal-field splitting around Ce³⁺ ion and doping orange-red emitting ion, were adopted to fabricate Ce:(Y,Tb)₃(Al,Mn)₅O₁₂ TCs via vacuum sintering technique. Notably, 85.4 % of the room-temperature luminescence intensity of the TC was retained at 150 °C, and the color rendering index was as high as 79.8. Furthermore, a 12 nm red shift and a 16.2 % increase of full width at half maximum were achieved owing to the synergistic effects of Tb³⁺ and Mn²⁺ ions. By combining TCs with a 460 nm blue chip, a warm white light with a low correlated color temperature of 4155 K was acquired. Meanwhile, the action mechanism of Tb³⁺ ion and the energy transfer between Ce³⁺ and Mn²⁺ ions were verified in prepared TCs.     

An orange-emitting phosphor BaSrGa4O8:Bi3+,K+ with unique one-dimensional chain structure for high index color WLEDs

It has been an urgent need for developing a new bright long-wave emitting phosphor to improve the color rendering index (CRI) of white light-emitting diodes (WLEDs). Here, based on the concept of oxygen vacancy-induced long-wave emission by Bi³⁺ doping, we selected BaSrGa₄O₈ as the matrix, which has a low-dimensional chain structure that can produce enough oxygen vacancies. After the introduction of Bi³⁺, orange emission was successfully achieved. To further improve the luminescence efficiency, the system of BaSrGa₄O₈:Bi³⁺,K⁺ was designed. Interestingly, although significant emission enhancement was obtained, the material showed reduced absorption with increased oxygen vacancies. More detailed experimental evidences confirm that oxygen vacancies can activate Bi³⁺ to achieve long-wave emission. Our results provide a new way to design Bi³⁺-based long-wave emitting phosphors with low-dimensional crystal structure. Finally, a WLED device containing BaSrGa₄O₈:Bi³⁺,K⁺ was fabricated and exhibited an enhanced CRI, which shows a promising application in WLEDs.     

Photoluminescence and energy transfer of Lu3Al5O12:Ce3+, Pr3+ phosphors

Ce³⁺ and Pr³⁺ co?doped Lu₃Al₅O₁₂ phosphors were synthesized by the sol–gel process, and their crystal structure, photoluminescence (PL) properties, and energy transfer (ET) from the Ce³⁺ to Pr³⁺ were studied. The Lu_2.94?yAl₅O₁₂:0.06Ce³⁺, yPr³⁺ phosphors (0.002 ≤ y ≤ 0.008) showed the green?yellow emission from the ²D_3/2 → ²F_{5/2, 7/2} transition of Ce³⁺ and the red emission at 610 and 637 nm, which were caused by the ¹D₂→³H₄ and ³P₀→³H₅ transitions of Pr³⁺, respectively. The optimal concentration of Pr³⁺ for efficient ET was found to be x = 0.006. The electric quadrupole?quadrupole interaction was responsible for the concentration quenching in the Lu_2.94?yAl₅O₁₂:0.06Ce³⁺, yPr³⁺ phosphors, based on Dexter's theory. The incorporation of Pr³⁺ for Lu³⁺ enhanced the red PL intensity in the Lu_2.94Al₅O₁₂:0.06Ce³⁺ phosphor.