Effects of Bi3+ on down-/up-conversion luminescence,temperature sensing and optical transition properties of Bi3+/Er3+ co-doped YNbO4 phosphors

A series of YNbO₄:Bi³⁺ and YNbO₄:Bi³⁺/Er³⁺ phosphors were prepared by a conventional high temperature solid–state reaction method. The results of XRD and Rietveld refinement confirm that monoclinic phase YNbO₄ samples are achieved. The down-/up-conversion luminescence of Er³⁺ ions was investigated under the excitation of ultraviolet light (327 nm) and near infrared light (980 nm). Under 327 nm excitation, broad visible emission band from Bi³⁺ ions and characteristic green emission peaks from Er³⁺ ions are simultaneously observed, while only strong green emissions from Er³⁺ ions are detected upon excitation of 980 nm. Remarkable emission enhancement is observed in down-/up-conversion luminescence processes by introducing Bi³⁺ ions into Er³⁺-doped YNbO₄ phosphors. Pumped current versus up-conversion emission intensity study shows that two-photon processes are responsible for both the green and the red up-conversion emissions of Er³⁺ ion. Through the study of the temperature sensing property of Er³⁺ ion, it is affirmed that the temperature sensitivity is sensitive to the doping concentration of Bi³⁺ ions. By comparing the experimental values of the radiative transition rate ratio of the two green emission levels of Er³⁺ ions and the theoretical values calculated by Judd-Ofelt (J-O) theory, it is concluded that the temperature sensing property of Er³⁺ ions is greatly affected by the energy level splitting.     

Synthesis and optical characterization of Eu2+,Tb3+-codoped Sr3Y(PO4)3 green phosphors

A series of Eu~(2+),Tb~(3+)-codoped Sr_3 Y(PO_4)_3(SYP) green phosphors were synthesized by hightemperature solid-state reaction. Several techniques, such as X-ray diffraction, UV-vis spectrum,and photoluminescence spectrum, were used to investigate the obtained phosphors. The present study investigates in detail photoluminescence excitation and emission properties, energy transfer between the two dopants, and effects of doping ions on optical band gap. SYP:0.05 Eu2+ phosphor shows an intense and broad excitation band ranging from 220 to 400 nm and exhibits a bright green emission band with CIE chromaticity coordinates(0.189, 0.359) under 350 nm excitation. Green emission of SYP:0.03 Tb3+ is intensified by codoping with Eu~(2+), and energy transfer mechanism between them is demonstrated to be a dipole-dipole interaction. Upon 350 nm excitation, SYP:Eu~(2+),Tb~(3+) phosphors exhibits two dominating bands peaking at 466 and 545 nm, which are assigned to 4 f~65 d~1→4 f~7 transition of Eu~(2+) ions and ~5 D_4→~7 F_5 transition of Tb~(3+) ions, respectively. Optimal doping concentrations of Eu~(2+) and Tb~(3+) in the SYP host are 5 mol% and 15 mol%, respectively. Results indicate that SYP:Eu~(2+),Tb~(3+) phosphors are potentially used as green-emitting phosphors for white light-emitting diodes.     

Y4GeO8:Er3+,Yb3+ up-conversion phosphors for optical temperature sensor based on FIR technique

Herein, we reported novel Y₄GeO₈:Er³⁺,Yb³⁺ phosphors elaborated via conventional solid-state reaction, and we further explored their properties as optical thermometer by using fluorescence intensity ratio (FIR) method complemented by detailed analysis on crystal structure, up-conversion luminescence and energy transfer from Yb³⁺ to Er³⁺. Upon 980 nm laser excitation, Y₄GeO₈:Er³⁺,Yb³⁺ phosphors present 525, 547 and 659 nm emission bands assigned to the characteristic transitions of Er³⁺. Furthermore, Y₄GeO₈:Er³⁺,Yb³⁺ samples show outstanding temperature sensing performances. To be specific, the minimal temperature resolution is 0.03 K (303 K), and the relative sensitivity of FIR can be up to 1.152%/K (303 K). Hence, Y₄GeO₈:Er³⁺,Yb³⁺ phosphors can be possible candidates for thermometry devices.     

Cooperative energy acceptor of three Yb3+ ions

Our previous work first reported the cooperative sensitized luminescence from Cu~(2+) or Pb~(2+) by three clustered Yb~(3+) ions, in which three NIR photons can be converted into a high energy photon. Could a reverse process happen that a high energy photon is cut into three NIR photons? This work demonstrated an example of three-photon quantum cutting(QC) phosphor,CaF_2:Ce~(3+),Yb~(3+), in which three clustered Yb~(3+) ions(Yb~(3+)-trimer) cooperatively and indirectly received a 306 nm ultraviolet(UV) photon energy transferred from a Ce~(3+) ion in 5 d excited state and emitted three 975 nm near-infrared(NIR)photons. The cluster destruction experiments were designed to verify the necessity of the presence of Yb~(3+)-trimers for QC. The dynamical analysis on luminescence of Ce~(3+) ions confirmed the energy transfer from Ce~(3+) ions to Yb~(3+)-trimers. The doping concentration effect on luminescence was investigated.Furthermore, the maximum energy transfer(ET) efficiency and the corresponding QC efficiency were estimated to be 61% and 222%, respectively. Therefore, the reported three-photon QC phosphor has an attractive prospect in efficiently harvesting solar energy for silicon solar cells.     

A single-phase full-color phosphor Sr2Ca2La(PO4)3O:Eu2+,Tb3+,Mn2+: Photoluminescence and energy transfer

A single-phase full-color emitting phosphor Sr₂Ca₂La(PO₄)₃O:Eu²⁺,Tb³⁺,Mn²⁺ was synthesized by the high temperature solid-state method. The phase formation, luminescence properties, thermal stability, and energy transfer from Eu²⁺ to Tb³⁺ and Eu²⁺ to Mn²⁺ in Sr₂Ca₂La(PO₄)₃O were investigated in details. Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu²⁺ to Tb³⁺ or Mn²⁺ ions by varying the ratio of Eu²⁺/Tb³⁺ or Eu²⁺/Mn²⁺ ions. White light was obtained with chromaticity coordinates of (0.3558, 0.3500) in the Sr₂Ca₂La(PO₄)₃O:0.04Eu²⁺,0.08Tb³⁺,0.40Mn²⁺ phosphor, suggesting their potential applications in white light emitting diodes.     

Synthesis and luminescence properties of Tb3+/Eu3+ co-doped GdAlO3 phosphors with enhanced red emission

The(Gd_(0.97-x)Eu_xTb_(0.03))AIO_3(x= 0.005-0.07) phosphors were synthesized by the co-precipitation method,using ammonium bicarbonate as a precipitant.The combined technologies of FT-IR,XRD,FESEM,PLE/PL and photo luminescence decay analysis were used to study the phase evolution,morphologies and luminescent properties.The phosphors with good dispersion exhibit strong vivid red emission located at 617 nm(~5 D_0-~7 F_2 transition of Eu~(3+)) under the optimal excitation wavelength of 275 nm(~4 f~8-4 f~75 d~1 transition of Tb~(3+),~8 S_(7/2)→6~I_J transition of Gd~(3+)).The presence of Gd~(3+) and Tb~(3+) excitation bands on the PLE spectra monitoring the Eu~(3+) emission directly gives an evidence of Tb~(3+) → Eu~(3+) and Gd~(3+) → Eu~(~(3+)) energy transfer,The emission intensity varies with the Eu~(3+) amount,and the quenching concentration is ～5 at% which is close to the calculated value.The quenching mechanism is determined to be the exchange reaction between Eu~(3+).The temperature-dependent PL analysis indicates that the best(Gd_(0.92)Eu_(0.05)Tb_(0.03))AlO_3 sample possesses good thermally stable properties.All the(Gd_(0.97-x)Eu_xTb_(0.03))AIO_3 phosphors in this work have similar CIE chromaticity coordinates and color temperatures,which are(0.65 ± 0.02,0.35 ± 0.02) and ～2558 K,respectively.Fluorescence decay analysis shows that the lifetime for～617 nm emission decreases with the content of Eu~(3+) and temperature increasing.Owing to the Tb~(3+)→ Eu~(3+) energy transfer,the luminescent properties of the(Gd_(0.92)Eu_(0.05)Tb_(0.03))AlO_3 phosphors are superior to the single Eu~(~(3+)) doped sample(Gd_(0.95)Eu_(0.05))AlO_3.As a result,the prepared phosphors may be widely used in solid-state display and light emitting devices.     

Synthesis,crystal structure and photoluminescence properties of novel double perovskite La2CaSnO6:Eu3+ red-emitting phosphors

A series of new double perovskite La_2–xEu_xCaSnO₆ (0 ≤ x ≤ 0.8) red phosphors were synthesized by traditional solid-state reaction. The phase, microstructure, photoluminescence (PL) properties, quantum efficiency, and thermal stability of the phosphors were investigated. La₂CaSnO₆ matrix has a monoclinic double perovskite structure with space group P2₁/n. Under near-ultraviolet (UV) light at 395 nm, La_2–xEu_xCaSnO₆ phosphors exhibit the most typical red emission peak at 614 nm, which corresponds to ⁵D₀→⁷F₂ electric dipole transition of Eu³⁺. The optimum Eu³⁺ doping content is attained at x = 0.5, and the La_1.5Eu_0.5CaSnO₆ phosphor shows a moderate quantum efficiency (32.3%) and high color purity (92.2%). Besides, the temperature-dependent spectrum of the phosphor was studied. The emission intensity of Eu³⁺ at 423 K decreases to 70.94% of the initial intensity at 303 K, and the activation energy ΔE is estimated to be 0.232 eV, suggesting that the phosphors possess good thermal stability. The fabricated w-LED based on the phosphors has higher R_a (89), lower CCT (4539K), and better chromaticity coordinates (0.371, 0.428). These results prove that the Eu³⁺-doped La₂CaSnO₆ red phosphor has great potential applications in w-LEDs.     

Synthesis and photoluminescence properties of Er3+ and Dy3+ doped Na2NbAlO5 phosphors

A series of Ln³⁺ (Ln³⁺ = Er³⁺/Dy³⁺) ions doped Na₂NbAlO₅ (NNAO) phosphors were synthesized by solid-state method. The Er³⁺ and Dy³⁺ ions doped phosphors were characterized by XRD, photoluminescence (PL) and decay profiles. The Ln³⁺-doped samples are consistent with the pure NNAO phase which is analyzed by the X-ray diffraction result. The PL graphs show that the intensity of luminescence increases with the increasing doping concentrations up to their critical certain values and then decreases at higher concentrations due to the concentration quenching effect of Er³⁺/Dy³⁺ ions. The energy level diagrams containing the positions of 4f and 5d energy levels of Er³⁺ and Dy³⁺ ions have been established and studied. In addition, under the ultraviolet light, the prepared NNAO:xLn³⁺ (Ln³⁺ = Er³⁺/Dy³⁺) phosphors show the characteristic green (Er³⁺), cyan (Dy³⁺) emission, respectively. Under the excitation of 365 nm, the quantum efficiencies of NNAO:0.01Er³⁺ and NNAO:0.03Dy³⁺ phosphors are measured to be 61.7% and 72.2%, respectively. The obtained results indicate that the new NNAO:xLn³⁺ (Ln³⁺ = Er³⁺/Dy³⁺) phosphors are promising applications in white-light emitting diodes field.     

Improving luminescence and thermometric performance of Ba2CaWO6:Er3+ by tri-doping with Yb3+ and Na+

The Er³⁺doped double perovskite Ba₂ CaWO₆ crystal is a promising ratiometric thermometer based on the fluorescence intensity ratio(FIR) of transitions from ² H_11/2 and ⁴ S_3/2to the lowered ⁴ I_15/2 level.However,the Ca²⁺vacancy defect caused by the charge difference between rare-earth ions and the substituted alkaline-earth ions gives rise to the non-radiative probability and limits the t...     

Upconversion multicolor tuning of NaY(WO4)2:Tb3+ with Eu3+ doping

A series of Tb~(3+) and Eu~(3+) co-doped NaY(WO_4)_2 phosphors were synthesized by hydrothermal reactions.The crystal structure,morphology,upconversion luminescent properties,the energy transfer from Tb~(3+) to Eu~(3+)ions and the ~5 D_4→ ~7 F_5 transition of the Tb~(3+) ion in NaY(WO_4)_2:Tb~(3+),Eu~(3+) phosphors were investigated in details.The results indicate that all the synthesized samples are of pure tetragonal phase NaY(WO_4)2.Furthermore,the micrometer-sized needle spheres and excellent dispersion of the particles are obtained by adding polyethylene glycol(PEG-2000) as the surfactant.Phosphors of NaY(WO_4)_2:Tb~(3+),Eu~(3+) exhibit the492 nm blue emission peak,546 nm green emission peak,595 nm orange emission peak and 616 nm red emission peak under 790 nm excitation.The energy transfer from Tb~(3+) to Eu~(3+) is a resonant transfer,in which electric dipole-dipole interaction plays a leading role.By adjusting the doping concentration of Eu~(3+) in NaY(WO_4)_2: 1.0 mol%Tb~(3+),xmol%Eu~(3+) phosphors,the emitting color of UC phosphors can be tuned from green to red.     

Tunable emission,energy transfer and thermal stability of Ce3+, Tb3+ co-doped Na2BaCa(PO4)2 phosphors

A series of single Ce³⁺ doped and Ce³⁺ and Tb³⁺ co-doped Na₂BaCa(PO₄)₂ (NBCP) phosphors was synthesized by conventional solid-stated reaction method. The crystal structure, luminescence properties, thermal stability and energy transfer were carefully investigated. Ce³⁺ is inferred to substitute the Ba²⁺ site in NBCP lattice. The color-tunable emission from blue to green is observed by adjusting Tb³⁺ concentration among NBCP:0.03Ce³⁺,yTb³⁺ phosphors. The energy transfer behavior from Ce³⁺ to Tb³⁺ ions is both illustrated by co-doped PL spectra and decay curves. The energy transfer efficiency is as high as 91.5%. The mechanism of energy transfer is resonance type of dipole-dipole transition. In this work, the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150 °C. The Ce³⁺ and Tb³⁺ co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.     

Synthesis and luminescent properties of BaGd2O4:Eu3+ phosphors with highly efficient red-emitting

The BaGd_(2-2 x)Eu_(2 x)O_4(BG, x = 0.01-0.09) phosphors were successfully synthesized via the sol-gel method,and BaY_(2-2 y)Eu_(2 y)O_4(BY, y = 0.005-0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe_2 O_4-type structure are obtained by annealing at 1300℃ for5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu~(3+)emission with the strongest peak at 613 nm(~5 D_0→~7 F_2 transition of Eu3+) under optimal excitation band at 262 nm(CTB band). The presence of Gd~(3+) excitation bands on the PLE spectra monitoring the Eu3+emission directly proves an evidence of Gd~(3+)-Eu~(3+) energy transfer. Owing to the concentration quenching, the optimum content of Eu3+ addition is 5 at%(x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu3+. All the BG samples have similar color coordinates and temperature of(0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K,respectively. The lifetime value of BaGd_(1.9)Eu_(0.1)O_4 for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu~(3+) concentration does not change the lifetime significantly. Owing to the Gd~(3+)-Eu~(3+) energy transfer, the luminescent intensity of the BaGd_(1.9)Eu_(0.1)O_4 phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas.     

Luminescence properties of Pr3+ and Bi3+ co-doped NaCaTiNbO6 phosphor for red-LEDs

This paper investigates the photoluminescence properties of NaCaTiNbO_6:Pr~(3+) and NaCaTiNbO_6:Pr~(3+),Bi~(3+) phosphors. NaCaTiNbO_6:Pr~(3+) and NaCaTiNbO_6:Pr~(3+),Bi~(3+) powder were synthesized successfully by solid state reaction method. Phase purity was checked using X-ray powder diffractometry(XRD). The excitation and emission spectra were recorded to elucidate the photoluminescence properties of NaCaTiNbO_6:Pr~(3+) and NaCaTiNbO_6:Pr~(3+),Bi~(3+). Furthermore,fluorescence lifetime measurements were performed. The excitation spectra of NaCaTiNbO_6:Pr~(3+) show a main band centered at around 357 nm.The luminescence spectra of NaCaTiNbO_6:Pr~(3+) exhibit a red emission peak at 615 nm from the ~1 D_2→~3 H_4 transition of Pr~(3+) ions. With the introduction of the Bi~(3+) ion into NaCaTiNbO_6:Pr~(3+), the luminescence intensity is enhanced nearly two times. Meanwhile,the absorption band edge of NaCaTiNbO_6:Pr~(3+) is shifted from 380 to 420 nm. Thus, this study shows that the red phosphor NaCaTiNbO_6:Pr~(3+) incorporated with Bi~(3+) is advantageous for light-emitting diode applications.     

Synthesis and luminescent properties of Ba3Y3.88Gd0.12O9:Eu3+ phosphors with enhanced red emission

In this work, the Gd³⁺/Eu³⁺ activated Ba₃Y₄O₉ (BYO) phosphors were successfully synthesized via coprecipitation method at 1400 °C. The precursor composition, crystal structure stability, microscopic morphology, photoluminescence (PL)/photoluminescence excitation (PLE) spectra and fluorescence attenuation analysis of the phosphors are discussed in detail. The chemical composition of the precursor was determined by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG) analysis; According to field emission-scanning electron microscopy (FE-SEM) analysis, it is found that the particle size of phosphor is uniform and the agglomeration is few. According to PL/PLE spectra analysis, Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors has the strongest excitation band at 260 nm and the strongest emission band at 614 nm, and the fluorescence intensity of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ is higher than that of Ba₃Y_3.4Eu_0.6O₉. The quenching concentration of Eu³⁺ in Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors is x = 0.15 and the mechanism of quenching concentration of Eu³⁺ is electric dipole-quadrupole type interactions. The lifetime value of Ba₃Y_3.88–4xEu_4xGd_0.12O₉ (x = 0.15) phosphors is 0.686 ms and decreases with the increase of Eu³⁺ content. In addition, the CIE chromaticity diagram of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors is (0.66, 0.34). Finally, the lamp beads assembled with Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors have an ideal luminous effect. Therefore, the Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors designed in this work may hopefully meet the requirements of various lighting and optical display applications.     

White up-conversion luminescence and highly-sensitive optical temperature sensing in Na3La(VO4)2:Yb,Er,Tm,Ho phosphors

In this work,tunable white up-conversion luminescence was achieved in the Yb³⁺,Er³⁺,Tm³⁺,Ho³⁺ codoped Na₃La(VO₄)₂ phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the ²H_11/2/⁴S_3/2→⁴I_15/2 transitions of Er³⁺,¹G₄→³H₆ transition of Tm³⁺,and_5...     

EXAFS investigation and luminescent properties of nanosized Tb: Lu2O3 phosphors

Nanosized terbium doped Lu2O3 phosphors were synthesized via a modified co-precipitation processing.The as-prepared Tb:Lu2O3 phosphors was consisted of well crystallized nanosized sphere particles with a diameter of about 30 nnx Local structure of Tb ions in Lu2O3 lattice was investigated by an analytical approach based on Fourier transformation of the extended X-ray absorption fine structure(EXAFS) data.X-ray near edge structure (XANES) spectra suggested that all Tb ions doped were tervalonce.EXAFS results indicated that Tb ions have entered the Lu2O3 cubic lattice by means of solid solution.The coordination number and first shell Tb-O distance dropped with the increasing of Tb concentration.Emission spectra of the phosphors was shown to be typical for Tb3+ with main components at 542,550 and 490 nm,derived from irradiative relaxation of 5D4 level.The emission intensity decreased severely with the increasing of Tb concentration from 1 mol.% to 15 tool.%,suggesting a significant concentration quenching above 1 mol.% Tb.The reduction of emission intensity was interpreted by higher distortion derived relaxation among the surface state resident Tb3+ ions.     

A NIR to NIR rechargeable long persistent luminescence phosphor Ca2Ga2GeO7:Yb3+,Tb3+

Near infrared to near infrared (NIR–NIR) photo-stimulated persistent luminescence (PSPL) has shown excellent potential in high-resolution bioimaging for deep tissues. However, the PSPL in NIR-Ⅱ region (900–1700 nm) is still lacking. In this work, Ca₂Ga₂GeO₇:Yb³⁺,Tb³⁺ (CGGYT) phosphor with unique low-dimensional crystal structure was synthesized by high-temperature solid–state reaction. Thanks to the carriers transferring from deep traps to shallow ones induced by low energy light, the 978 nm PSPL originating from ²F_5/2 to ²F_7/2 transition of Yb³⁺ induced by multimode stimulating (980 nm or WLED) is successfully realized after pre-excited by UV lamp. The NIR PSPL of the specimen can be repeatedly stimulated after placed in dark for 12 h. Moreover, the results indicate that codoping with Tb³⁺ can significantly enhance the NIR-II PSPL owing to the quantum cutting persistent energy transfer (QC PET) from Tb³⁺ to Yb³⁺. Our study points to a new direction for the future development of multimode PSPL materials for bioimaging or multimode optical storage applications.     

Preparation and luminescence properties of orange-red Ba3Y4O9:Sm3+ phosphors

A novel orange-red emitting Ba₃Y₄O₉:Sm³⁺ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra, fluorescence decay and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties. The results show that the excitation spectrum includes a series of linear peaks at 350, 367, 382, 410, 424, 445, 470 and 495 nm, respectively. Under 410 nm excitation, the emission peaks were located at 574 nm (⁴G_5/2—⁶H_5/2), 608 nm (⁴G_5/2—⁶H_7/2), 659 nm (⁴G_5/2—⁶H_9/2) and 722 nm (⁴G_5/2—⁶H_11/2), respectively. The concentration quenching occurs when x equals 0.08 for Ba₃Y_4–xO₉:xSm³⁺ phosphor and its mechanism is ascribed to the dipole–dipole interaction. The chromaticity coordinates of Ba₃Y_3.92O₉:0.08Sm³⁺ phosphor are in the orange-red region. The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability. And the luminescence intensity of Ba₃Y_3.92O₉:0.08Sm³⁺ phosphor at 473 K only declines by about 25.75% of its initial intensity. The experimental data indicate that Ba₃Y₄O₉:Sm³⁺ phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.     

Structure and luminescence properties of color-tunable phosphor Sr2La3(SiO4)3F:Tb3+,Sm3+

A series of single-phase and color-tunable phosphors Sr₂La₃(SiO₄)₃F:0.15Tb³⁺,xSm³⁺(SLSOF:0.15Tb³⁺,xSm³⁺) was prepared using solid-state route.The X-ray diffraction(XRD) was used to characterize the phase of the as-prepared samples.The synthesized phosphors have apatite-type structure without other impurities.Sm³⁺ and Tb³⁺ ions substitute La³⁺ into the lattice and form a single...     

White-light emitting single-phase phosphor La3Si6N11:Dy3+,Tb3+: Color tunable emission,thermal stability and energy transfer process

A novel white-light emitting single-phase phosphor La₃Si₆N₁₁:Dy³⁺, exhibiting two emission peaks centering at 475 and 575 nm, was prepared via conventional solid-state reactions. The structure and morphology of La₃Si₆N₁₁:Dy³⁺/Tb³⁺ were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The emission colors can be tuned from white to yellow-green through increasing the Tb³⁺ concentration in La₃Si₆N₁₁:Dy³⁺,Tb³⁺. The mechanism of energy transfer (ET) from Dy³⁺ to Tb³⁺ is confirmed according to the excitation, emission spectra and decay lifetimes curve. The temperature-dependent luminescence measurements of La_2.83Si₆N₁₁:0.1Dy³⁺,0.07Tb³⁺ were also performed, and a good thermal stability is shown, suggesting superior properties for the application as white light-emitting diodes (w-LEDs) phosphor.