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.     

Luminescent ionic lattice occupation and wide tunable emission spectra of La2MgZrO6:Bi3+,Eu3+ double perovskite phosphors for white light LED

La₂Mg_1-x/2Zr_1-x/2O₆:xBi³⁺(x=0.01-0.035,abbreviated as LMZ:Bi³⁺) and La_2-yMg_0.99Zr_0.99O₆:0.02Bi³⁺,yEu³⁺(y=0.1-0.11,abbreviated as LMZ:Bi³⁺,Eu³⁺) double-perovskite phosphors were prepared through high-temperature solid-phase method.The emission spectrum of LMZ:xBi³⁺(x=0.01-0.035)phosphors excited at 353 nm is asymmetric in the range be...     

Eu2+-doped Sr5(PO4)3Br blue-emitting phosphor with high color purity for near-UV-pumped white light-emitting diodes

Eu²⁺-doped bromophosphateapatite Sr₅(PO₄)₃Br phosphors were synthesized by the conventional high-temperature solid-state reaction. The crystal structure and luminescence properties of the phosphors, as well as their thermal stability and CIE chromaticity coordinates were systematically investigated. Photoluminescence spectra of Sr₅(PO₄)₃Br:Eu²⁺ exhibit a single blue emission at 450 nm under the excitation of 345 nm, which is ascribed to the 4f–5d transition of Eu²⁺. The phosphor shows very good thermal stability. The CIE color coordinates are very close to those of BaMgAl₁₀O₁₇:Eu²⁺ (BAM). All the properties indicate that the blue-emitting Sr₅(PO₄)₃Br:Eu²⁺ phosphor has potential application in white LEDs.     

Influence of reaction parameters on the luminescence properties of monodisperse NaGd(1−x−y)(WO4)2:xEu3+,yTb3+ phosphor by molten salt synthesis

Eu~(3+) activated and Eu~(3+), Tb~(3+) co-activated monodisperse sodium double tungstates NaGd(WO4)2 phosphors were prepared by molten salt method at 750 ℃ for 10 h using NaCl as a flux. The crystal structure and morphology of the as-synthesized phosphors were measured by XRD and SEM, respectively. The photoluminescence properties were characterized by PL spectra, decay lifetime and CIE. The presence of NaCl plays an important role in the morphology and luminescence properties. In this work,NaCl and one of the raw material Na_2 CO_3 in a certain proportion will form a low eutectic salt to decrease the reaction temperature and benefit the formation of monodisperse NaGd(WO_4)_2 crystals. The color of Eu~(3+) and Tb~(3+) co-doped NaGd(WO_4)_2 phosphors can be tuned from creamy white to orange, red and green by adjusting the doping concentration of rare earth ions, since the emission contain the broad blue-green emission origin from NaGd(WO_4)_2 host and characteristic red and green emission origin from Eu~(3+) and Tb~(3+) ions. The electroluminescent spectra and CIE measurement shows that the LED device with NaGd_((1-x))(WO_4)_2:xEu~(3+)(x = 0.24) phosphor can be excited by 365 nm and 380 nm LED chip, and their CIE coordinate is(x = 0.45, y = 0.45) and(x = 0.36, y = 0.37), Ra is 80.3 and 86.3, T_c is 3196 and4556 K, respectively. As a single-component phosphor, NaGd(WO_4)_2:Eu~(3+),Tb~(3+) have potential application in UV-pumped WLEDs.     

Enhanced afterglow performance of CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors by co-doping Gd~(3+)

In order to effectively improve the afterglow properties of CaAl_2 O_4:Eu~(2+),Nd~(3+) phosphors,a series of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)(x=0,0.012,0.024,0.036,0.048,0.060 mol) phosphors were prepared by a high-temperature solid-phase approach.Crystalline composition and microstructure were characterized by XRD,TEM,HRTEM,and XPS,luminescence properties were systematically analyzed by fluorescence spectra,afterglow decay curves and TL glow curve.Results show that all of Ca_(0.982-x)Al_2 O_4:0.012 Eu~(2+),0.006 Nd~(3+),xGd~(3+)phosphors belong to monoclinic CaAl_2 O_4,without other cystalline phase.The blue emission at 442 nm is observed,which is assigned to the 4 f~65 d→4 f~7 transition of Eu~(2+) ions.Doping with appropriate amount of Gd~(3+) ions(x=0.036 mol) significantly improves the afterglow properties of phosphors,but the excessive doping of Gd~(3+) induces the fluorescent quenching.The doping of moderate Gd3+changes the traps states,the trap depth varies from 0.598 to 0.644 eV and the trap concentration is also greatly improved,thus significantly improving afterglow performance.     

Tunable luminescence in co-doped Zn3Al2Ge2O10:Cr3+ by controlling crystal field splitting and nephelauxetic effect

Ce³⁺/Dy³⁺/Tb³⁺/Eu³⁺/Mn²⁺ and Cr³⁺ ions co-doped Zn₃Al₂Ge₂O₁₀ phosphor were prepared by a high-temperature solid-state method. X-ray diffraction patterns prove the cubic phase structure of prepared Zn₃Al₂Ge₂O₁₀ phosphor. Emission, excitation spectra and decay curves confirm the tunable luminescence. Different degrees of the decrease of emission FWHM in Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,RE (RE = Ce³⁺, Dy³⁺, Tb³⁺, Eu³⁺) and Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,Mn²⁺ are observed. The reason of variable FWHM is the effect of crystal field splitting and nephelauxetic effect, and the nephelauxetic effect is dominant. Therefore, the emission FWHM decreases with the increasing concentration of Mn²⁺/Tb³⁺/Eu³⁺ in Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺, and for Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,Ce³⁺ and Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,Dy³⁺, it is a constant. The variation of Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,Tb³⁺ is more obvious than that of Zn₃Al₂Ge₂O₁₀:0.02Cr³⁺,Eu³⁺, because Tb³⁺ ion has smaller electronegativity. Thus, the tunable luminescence of Cr³⁺ can be realized by co-doping different ions. And these phosphors have potential applications in light-emitting diodes for plant growth.     

A comparison research on replacements of Ba2+ by Lu3+ and Ba2+-Si4+ by Lu3+-Al3+ in BaSi2O2N2:Eu phosphors

As a cyan-emitting oxonitridosilicate phosphor,BaSi₂O₂N₂:Eu²⁺can be used as a competent cyan compensator to improve the color rendering index of white light-emitting diodes(WLEDs).However,low luminescence efficiency and poor thermal stability of this type of phosphor seriously suppress its actual application in full-spectrum lighting.The replacements of Ba²⁺by Lu³⁺and Ba²⁺-Si⁴⁺by Lu³⁺-Al³⁺can greatly increase the luminescence intensity and improve the thermal stability at the same time.With Lu³⁺doping,the internal quantum efficiencyηIQE Ba_0.925Si₂O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺is 24.08%higher than that of Ba_0.97Si₂O₂N₂:0.03 Eu²⁺.After Al³⁺co-doping,theηIQE is further increased by 10.31%compared to Ba_0.925Si₂O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺.When the temperature rises to 473 K,the luminescence intensity of Ba_0.925Si₂O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺maintains 62.32%of that at room temperature,which increases by 17.35%in relative to the Ba_0.97Si₂O₂N₂:0.03 Eu²⁺,while the luminescence intensity of Ba_0.925Si_1.97O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺,0.03 Al³⁺keeps 73.87%of the initial value,which increases by18.52%compared to Ba_0.925Si₂O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺.The mechanisms for luminescence and thermal stability improvement are proposed.The Ba_0.925Si_1.97O₂N₂:0.03 Eu²⁺,0.045 Lu³⁺,0.03 Al³⁺cyan phosphor,Y3 Al5 O12:Ce3+yellow phosphor and CaAlSiN3:Eu²⁺red phosphor are mixed thoroughly and coated on a blue LED(450 nm)to assemble a WLED.The WLED demonstrates a color rendering index(Ra)of 97.1 at150 mA,and the R1-R15 values are all above 90.The results indicate that as an effective cyan compensator in WLED,the BaSi₂O₂N₂:Eu²⁺,Lu³⁺,Al³⁺phosphor has great application prospect in the field of full-spectrum lighting.     

Optical and luminescence characteristics of Eu3+-doped B2O3:SiO2:Y2O3:CaO glasses for visible red laser and scintillation material applications

Europium(Eu~(3+)) doped glasses of chemical compositions(55-x)B_2O_3:10 SiO_2:25 Y_2O_3:10CaO:xEu_2O_3,where x denotes mol% and ranges 0≤ x ≤ 2.5, were synthesized by adopting conventional melt quenching technique, Physical properties like density, molar volume, polaron radius, inter-ionic distance and field strength of the glass samples were investigated to assess the impact of Eu_2O_3. Optical and luminescence properties of the glasses were characterized with optical absorption, photoluminescence,X-ray induced emission spectra, temperature dependence emission spectra and decay times. Judd-Ofelt(JO) intensity parameters(Ω_λ) of the glasses were evaluated based on the absorption spectrum of 0.5 mol%. JO parameters, calculated from absorption spectra with thermal corrections on oscillator strength, were used to evaluate radiative properties such as radiative transition probability(A_R),branching ratio(β_R), stimulated cross section emission(σ) and radiative lifetime(τ_R) for ~5D_0→~7 F_J(J = 0,1,2,3 and 4) transitions. The decay rate of ~5D_0 fluorescent level for all the glass samples was single exponential. Lifetimes of the ~5D_0 level were decreased with increasing concentrations of Eu~(3+)ions from 0.05 mol% to 2.5 mol% which might be due to energy transfer through cross-relaxation in the glasses. The chromaticity coordinates(x, y) were similar for all BSYCaEu glasses and were located at the red region of CIE 1931 color chromaticity diagram. Hence, these results confirm that the Eu~(3+) doped BSYCaEu glasses could be useful for visible red lasers and glass scintillation applications.     

Luminescence thermal quenching of M_2SiO_4:Eu~(2+)(M=Sr,Ba) phosphors

In this paper,luminescence thermal quenching of M_2SiO_4:Eu~(2+)(M=Sr,Ba) orthosilicate phosphors and mechanisms for thermal quenching proposed by different authors are briefly reviewed.Depending on preparation conditions and/or Eu~(2+)-doping concentrations,the quenching temperature(T_(1/2)) and activation energy for thermal quenching of the same orthosilicate phosphor reported by different authors are inconsistent.The common conclusion is that T_(1/2) of the intermediate compound(Ba_(1-x)Sr_x)_2 SiO_4:Eu~(2+)(x≈0.5) is higher than that of either Sr_2So_4;Eu~(2+)or Ba_2SiO_4;Eu~(2+)end-member.Moreover,T_(1/2) of the best-performing SrBaSiO_4:Eu~(2+)is evidently lower than that of YAG:Ce~(3+)and some Eu~(2+)-doped nitride phosphors.Rega rding the quenching mechanism,most of the investigators attributed thermal quenching to a thermally assisted 4f-5d cross-over in the configuration coordinate diagram.Only a few authors ascribed thermal quenching to a thermally assisted photoionization of 5 d electron to conduction band of the host.Nonetheless,a close inspection of T_(1/2) and Stokes shift derived from the vibrational spectra of the intermediate compound and end-member phosphors indicates that the 5d electron photo ionization model instead of the 4f-5d crossing decay model should be the genuine mechanism for the thermal quenching of M_2 SiO_4:Eu~(2+)(M=Sr,Ba) phosphors.Since the relationship between T_(1/2) and Stokes shift of the phosphors does not support the 4 f-5 d crossing decay model.The ionization probability of the 5 d electron depends on the energy gap(E_(dC)) between 5 d_1 level of the Eu~(2+)and conduction band minimum(CBM) of the host at higher temperatures.Lattice thermal expansion would result in an elevating 5 d_1 level of the Eu~(2+)along with a diminishing CBM of the host and as a consequence a reduction in E_(dC) and an enhanced photo ionization probability at elevated temperatures.A less rigid lattice and hence a larger coefficient of thermal expansion of M_2SiO_4 hosts should be the physical origin of poorer thermal quenching properties of the orthosilicate phosphors.     

Single-phase white-emitting and tunable color phosphor Na3Sc2(PO4)3:Eu2+,Dy3+: Synthesis,luminescence and energy transfer

A series of Eu²⁺/Dy³⁺ single doped and co-doped Na₃Sc₂(PO₄)₃ phosphors were synthesized by the high-temperature solid-state method, and their phase, morphology, and luminescence properties were characterized. Under the excitation of 370 nm, the Na₃Sc₂(PO₄)₃:Eu²⁺,Dy³⁺ phosphor can emit white light whose spectrum is composed of a broad emission band centered at 460 nm and the other three peaks at 483, 577, and 672 nm, respectively. There is energy transfer from Eu²⁺ to Dy³⁺ ion in Na₃Sc₂(PO₄)₃:Eu²⁺,Dy³⁺ phosphor due to the good overlap between the emission spectrum of Na₃Sc₂(PO₄)₃:Eu²⁺ and the excitation spectrum of Na₃Sc₂(PO₄)₃:Dy³⁺, which is further confirmed by the fluorescence lifetime decrease of Eu²⁺ ion with the increase of Dy³⁺ concentration. The process of energy transfer is via dipole–quadruple interaction which is confirmed by applying Dexter's theory. By increasing the Dy³⁺ concentration, the color coordinates of the Na₃Sc₂(PO₄)₃:0.01Eu²⁺,xDy³⁺ phosphors can be adjusted from blue to white, and then to yellow. The optimized concentration of Dy³⁺ ions is 4.0 mol%, beyond which the concentration quenching will take place. The Na₃Sc₂(PO₄)₃:Eu²⁺,Dy³⁺ phosphor shows fairly good resistance to thermal quenching behavior, of which the emission intensity at 423 K can maintain 90.3% of the initial value (298 K). These results suggest that the Na₃Sc₂(PO₄)₃:0.01Eu²⁺,xDy³⁺ phosphors have potential applications as the color-tunable or a single-phase white emitting phosphor in white LEDs.     

Synthesis and luminescence properties of a novel phosphor Ca2–x/2Si1–xPxO4:Eu2+for near UV-excited white-light-emitting diodes

A novel green-emitting phosphor,Eu2+-doped Ca2-x/2 Si1-x Px O4(0.25≤x≤0.30),was prepared through a conventional solidstate reaction.X-ray diffraction(XRD),photoluminescence(PL) and decay studies were employed to characterize the sample,which was assigned to P63mc space group in the hexagonal system.The effect of P-doping on the α-Ca2 SiO4 was studied and P2 O5 broken down by the raw material of(NH4)2 HPO4 played an important role in stabilizing α-Ca2 SiO4 which can only be stable at high temperature.The XRD patterns of the Ca2-x/2 Si1-x Px O4 host were found pure and optimized when the mole fraction of P2 O5 was 14.5%.The diffuse reflectance spectra of the Ca1.855 Si0.71 P0.29 O4 and Ca1.845 Si0.71 P0.29 O4 :0.01Eu2+covered the spectral region of 230-400 nm,implying that the phosphor was suitable for UV or near-UV LED excitation.The phosphor could be effectively excited in the near UV region with the maximum at 372 nm.The emission spectrum of the Ca1.845 Si0.71 P0.29 O4 :0.01Eu2+phosphor showed an asymmetrical single intensive band centered at 513 nm,which corresponded to the 4f65d1→4f7transition of Eu2+.Eu2+ions might occupy two types of Ca2+sites in the Ca1.855 Si0.71 P0.29 O4 lattice and form two corresponding emission centers,which led to the asymmetrical emission of Eu2+in Ca1.855 Si0.71 P0.29 O4.The effects of Eu2+-doped concentration in Ca1.855-x Si0.71 P0.29 O4 :xEu2+on the PL were also discussed,the optimum doping concentration of Eu2+was 1 mol.% and the critical distance of the energy transfer was also calculated by the concentration-quenching method.The non-radiative energy transfer between Eu2+seemed to be caused by the multipole-multipole interaction.The fluorescence lifetime of Eu2+was found to be 0.55711 μs.The results suggested that these phosphors might be promising candidates used for near UV light excited white LEDs.     

Effect of fluxes on synthesis and luminescence properties of BaSi2O2N2:Eu2+ oxynitride phosphors

Eu²⁺ activated BaSi₂O₂N₂ oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF₂, Na₂CO₃ and NH₄Cl were used as the fluxes. The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photoluminescence properties. The results indicate that with the addition of BaF₂ flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi₂O₂N₂:Eu²⁺ phosphor can be improved effectively. The photoluminescence intensity of BaSi₂O₂N₂:Eu²⁺ phosphor with BaF₂ as flux gets enhanced obviously, which is much higher than that of Na₂CO₃, NH₄Cl and without flux. The optimum content of BaF₂ flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi₂O₂N₂:Eu²⁺ phosphor prepared with BaF₂ flux rises to 141%, meanwhile, the phosphors with BaF₂ flux exhibits low thermal quenching. The results indicate that the BaSi₂O₂N₂:Eu²⁺ is sort of promising bluish-green phosphor for application in full-spectra LED.     

Luminescence properties of composite material Sr2MgSi2O7:Eu2+,Dy3+/light conversion agent with multilayer structure

In order to improve the red luminescent properties,Sr₂ MgSi₂ O₇:Eu²⁺,Dy³⁺was selected as a blue persistent luminescent donor phosphor,while light conversion agent was utilized to tune the persistent luminescent spectra from blue to red.Composite red luminescent material Sr₂ MgSi₂ O₇:Eu²⁺,Dy³⁺/light conversion agent(SMED/LCA) was fabricated with light conversion agent and Sr₂ M...     

A green-yellow emitting β-SreSiO4：Eu^2＋ phosphor for near ultraviolet chip white-light-emitting diode

Sr2SiO4：xEu^2＋ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4：xEu^2＋ phosphor manipulated by Eu^2＋ concentration was studied. The phase transited from β to α＇ in Sr2SiO4：xEu^2＋ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α＇ phase when x〉0.01. The emission spectrum of the β-Sr2SiO4：Eu^2＋ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4：Eu^2＋ phosphors were fabricated. The luminous efficiency （15.7lm/W） was higher than α＇-Sr2SiO4：Eu^2＋ phosphor white LED.     

Luminescence properties of red phosphors Ca_（10）Li（PO_4）_7：Eu~（3＋）

A series of red phosphors Ca10Li (PO4)7:Eu3+ were synthesized by high temperature solid-state reaction method. Their luminescence properties were characterized by means of photoluminescence excitation and emission spectra,CIE chromaticity and quantum efficiency. Results indicated that the phosphors could be effectively excited by the near ultraviolet (NUV) light (393 nm). The main emission peaks of the phosphor were ascribed to the transition 5D0-7F2 (613 and 617 nm) of Eu3+ ion when samples were excited by...     

Characterization of Y2O2S： Eu^3＋, Mg^2＋, Ti^4＋ Long-Lasting Phosphor Synthesized by Flux Method

Long-lasting phosphor Y₂O₂S: Eu³⁺, Mg²⁺, Ti⁴⁺ was synthesized by a flux method and their luminescence properties were investigated. The result indicates that the unit cell parameter c is linearly increased with the increase of Eu₂O₃ content in Y₂O₂S: Eu_x³⁺ (0.01 ≤ x ≤ 0.10). On the other hand, the change of unit cell parameter a is not linear dependence. In the Y₂O₂S: Eu³⁺ crystal structure, Eu³⁺ ions only replaced Y³⁺ ions' places in which it posited center position of c axis. With the increase of Eu₂O₃ content, the position of the strongest emission peak changed from 540 nm (⁵D₁→⁷F₂ transition) to 626 nm (⁵D₀→⁷F₂ transition), and the maximum intensity was obtained when x = 0.09 in Y₂O₂S: Eu_x³⁺ (0.01 ≤ x ≤ 0.10). This is due to the environment of trivalent europium in the crystal structure of Y₂O₂S. Doping with Mg²⁺ or Ti⁴⁺ ions alone cannot get the good long-lasting afterglow effect, whereas co-doping with Mg²⁺ and Ti⁴⁺ ions and excited with 365 nm ultraviolet light, a strong thermoluminesence peak appeared, red and orange long-lasting phosphorescence (LLP) was also observed and the phosphorescence lasted nearly 3 h in the light perception of the dark-adapted human eye (0.32 mcd · m⁻²). Thus the LLP mechanism was analyzed.     

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.     

Phase structure and temperature dependent luminescence properties of Sr2LiSiO4F: Eu2+ and Sr2MgSi2O7: Eu2+ phosphors

Green-emitting Sr2LiSiO4F:Eu2+ and blue-emitting Sr2MgSi2O7:Eu2+ phosphors were synthesized by the conventional high temperature solid-state route,respectively.Their structures and photoluminescenee properties were comparatively investigated.It was found that the mixture phases of Sr2MgSi2O7 and SrF2 were obtained when a part of Sr2+ in Sr2LiSiO4F was replaced by some amount of Mg2+ in order to design the possible SrMgLiSiO4F:Eu2+ phosphor.Based on the photoluminescence analysis,Sr2LiSiO4F:Eu2+ phosphor exhibited a green broad emission band of main peak at 513 nm under the excitation of 365 nm,while the Sr2MgSi2O7:Eu2+ and SrMgLiSiO4F:Eu2+ phosphor showed blue emission centered at 467 nm.The temperature dependent photoluminescence properties and room temperature decay time for the three kinds of phosphors were also discussed in this paper.     

A novel Eu3+-doped phosphor-in-glass for WLEDs and the effect of borophosphate matrix

Phosphor-in-glass(PiG) is a potential color convertor for high power WLEDs.A novel glass matrix with advanced performance is still a challenge.Recently,Eu³⁺ doped glass matrix has attracted much consideration mainly due to its red compensation.A new borophosphate matrix to realize Eu³⁺ red light was designed in the Na₂O-ZnO-P₂O₅-B₂O₃-Eu₂O₃ system.Meanwhile,a series of PiGs composed of different con...     

Green and red phosphor for LED backlight in wide color gamut LCD

Wide color gamut(WCG) backlight for liquid crystal display(LCD) utilizing white light-emitting diodes(LED) has attracted considerable attention for their high efficiency and color reduction.In this review,recent developments in crystal structure,luminescence and applications of phosphors for wide color gamut LED backlight are introduced.As novel red phosphors,Mn~(4+)activate fluoride and aluminate phosphors are advanced in quantum efficiency,thermal quenching and color saturation for their characteristic spectrum with broad excitation band and linear emission.The crystal structure and fluorescence properties of Mn~(4+)doped fluosilicate,fluorogermanate,fluotitanate,as well as Sr_4 Al_(14)O_(25),CaAl_(12)O_(19) and BaMgAl_(10)O_(17) phosphors are discussed in detail.A serial of narrow-band red-emitting Eu~(2+),Eu~(3+)and Pr~(3+)-doped nitride silicates and molybdate phosphors are also introduced.Rare-earth-doped oxynitride and silicate green-emitting phosphors have attracted more and more attention because of the wide excitation,narrow emission,high quenching temperature,high quantum efficiency,such as β-sialon:Eu~(2+),Ba_3Si_6O_(12)N_2:Eu~(2+),MSi_2O_2N_2:Eu~(2+)(M=Ca,Sr,Ba),y-AlON:Mn~(2+)and Ca_3Sc_2Si_3O_(12):Ce~(3+).All above phosphors demonstrate their adaptability in wide color gamut LCD display.Especially for Mn~(4+)doped fluosilicate red phosphor and β-sialon:Eu~(2+)green phosphor.To achieve an ultra-high color gamut in white LED backlight and against the OLED,innovative narrow-band-emission red and green phosphor materials with independent intellectual property rights are continuously pursed.