Effect of Sr2+ doping on the luminescence properties of YVO4:Eu3+,Sr2+ particles prepared by a solvothermal method

Well-dispersed Eu³⁺ and Sr²⁺ co-doped YVO₄ luminescent particles (YVO₄:Eu³⁺,Sr²⁺) on the submicron scale were prepared by a facile solvothermal method at low temperature. The effect of Sr²⁺ doping on the luminescence of YVO₄:Eu³⁺,Sr²⁺ particles was investigated by fixing the Eu³⁺ doping concentration at 7 mol%. It was found that the luminescence intensity of the as-prepared YVO₄:Eu³⁺,Sr²⁺ particles increased with the Sr²⁺ doping concentration x to reach a two-fold enhancement when x = 5 %, and then decreased for higher x. We also investigated the effect of thermal annealing on the luminescence properties of the YVO₄:Eu³⁺ and YVO₄:Eu³⁺,Sr²⁺ particles. A remarkable enhancement in their luminescence properties was observed after annealing at 900 °C in air for 30 min. It was showed that the annealed YVO₄:Eu³⁺,Sr²⁺ particles exhibited a two-fold stronger emission than the annealed YVO₄:Eu³⁺. This work indicates that Sr²⁺ doping is beneficial to the luminescence enhancement for both the as-prepared and annealed YVO₄:Eu³⁺,Sr²⁺ particles.     

Enhancing the Photocatalytic Activity of Sr4Al14O25: Eu2+, Dy3+ Persistent Phosphors by Codoping with Bi3+ Ions

The photocatalytic activity of Bismuth‐codoped Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ persistent phosphors is studied by monitoring the degradation of the blue methylene dye UV light irradiation. Powder phosphors are obtained by a combustion synthesis method and a postannealing process in reductive atmosphere. The XRD patterns show a single orthorhombic phase Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺, Bi³⁺ phosphors even at high Bismuth dopant concentrations of 12 mol%, suggesting that Bi ions are well incorporated into the host lattice. SEM micrographs show irregular micrograins with sizes in the range of 0.5–20 μm. The samples present an intense greenish‐blue fluorescence and persistent emissions at 495 nm, attributed to the 5d–4f allowed transitions of Eu²⁺. The fluorescence decreases as Bi concentration increases; that suggest bismuth‐induced traps formation that in turn quench the luminescence. The photocatalytic evaluation of the powders was studied under both 365 nm UV and solar irradiations. Sample with 12 mol% of Bi presented the best MB degradation activity; 310 min of solar irradiation allow 100% MB degradation, whereas only 62.49% MB degradation is achieved under UV irradiation. Our results suggest that codoping the persistent phosphors with Bi³⁺ can be an alternative to enhance their photocatalytic activity.     

Tailoring of Deep‐Red Luminescence in Ca2SiO4:Eu2+

We report a new dicalcium silicate phosphor, Ca_2?xEu_xSiO₄, which emits red light in response to blue‐light excitation. When excited at 450 nm, deep‐red emission at 650 nm was clearly observed in Ca_1.2Eu_0.8SiO₄, the external and internal quantum efficiencies of which were 44 % and 50 %, respectively. The red emission from Ca_2?xEu_xSiO₄ was strongly related to the peculiar coordination environments of Eu²⁺ in two types of Ca sites. The red‐emitting Ca₂SiO₄:Eu²⁺ phosphors are promising materials for next‐generation, white‐light‐emitting diode applications.     

Inverse-Tunable Red Luminescence and Electronic Properties of Nitridoberylloaluminates Sr2−xBax[BeAl3N5]:Eu2+ (x=0–2)

The nitridoberylloaluminate Ba₂[BeAl₃N₅]:Eu²⁺ and solid solutions Sr_2−xBa_x[BeAl₃N₅]:Eu²⁺ (x=0.5, 1.0, 1.5) were synthesized in a hot isostatic press (HIP) under 50 MPa N₂ atmosphere at 1200 °C. Ba₂[BeAl₃N₅]:Eu²⁺ crystallizes in triclinic space group (no. 2) (Z=2, a=6.1869(10), b=7.1736(13), c=8.0391(14) Å, α=102.754(8), β=112.032(6), γ=104.765(7)°), which was determined from single-crystal X-ray diffraction data. The lattice parameters of the solid solution series have been obtained from Rietveld refinements and show a nearly linear dependence on the atomic ratio Sr : Ba. The electronic properties and the band gaps of M₂[BeAl₃N₅] (M=Sr, Ba) have been investigated by a combination of soft X-ray spectroscopy and density functional theory (DFT) calculations. Upon irradiation with blue light (440–450 nm), the nitridoberylloaluminates exhibit intense orange to red luminescence, which can be tuned between 610 and 656 nm (fwhm=1922–2025 cm⁻¹ (72–87 nm)). In contrast to the usual trend, the substitution of the smaller Sr²⁺ by larger Ba²⁺ leads to an inverse-tunable luminescence to higher wavelengths. Low-temperature luminescence measurements have been performed to exclude anomalous emission.     

The effect of calcium substitution on the afterglow of Eu2+/Dy3+ doped Sr4Al14O25

The effect of calcium substitution on the afterglow of tetrastrontium aluminate phosphors (Sr₄Al₁₄O₂₅:Eu²⁺, Dy³⁺) was investigated. A series of (Sr₁-_xCa_x)O⊎nAl₂O₃:Eu²⁺(1%), Dy³⁺(0.5%), with variation of calcium content (x = 0 − 1), were synthesized by a high temperature solid state reaction in a reducing atmosphere. The photoluminescence, persistent luminescence (afterglow), and lumen equivalents of these materials were studied and compared. It turned out that the afterglow properties of the phosphors were strongly dependent on the Sr/Ca ratio. As the Ca content increased, a phase transition and blue shift in emission spectra were observed.      

A Novel Synthesis of Alkaline Earth Silicate Phosphor Sr3MgSi2O8： Eu^2＋, Dy^3＋

A novel method for synthesizing long afterglow silicate phosphor Sr3MgSi2O8：Eu^2＋,Dy^3＋using TEOS and inorganic powders as reactants was reported. Acetic acid as a catalyzer controlled the hydrolysis of TEOS by adjusting pH value of the system. The morphologies of precursor were characterized by transmission electron microscope （TEM）. The structure and optical properties of the phosphor powders were systematically investigated by means of X-ray diffraction and spectrofluorometry. TEM images have reflected the core-shell structure and quasi-spherical morphology of the precursor particles. It was found that the single-phase Sr3MgSi2O8 crystalline structures were obtained at 1050 and 1250 ℃ for the samples prepared with the nano-coating method and the solid state reaction, respectively. The emission intensities of the phosphors prepared by the present method were higher than those by the conventional process. Also, the afterglow characteristic was better than that prepared by solid-state reaction in the comparable condition.     

Reddish-orange,neutral and warm white emissions in Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses

Eu³⁺, Dy³⁺ and Dy³⁺/Eu³⁺ doped CdO-GeO₂-TeO₂ glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with TeOTe and GeOGe related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370–420 nm) based LEDs. The Eu³⁺ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy³⁺ singly doped glass excited at 388 nm. The Dy³⁺/Eu³⁺ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy³⁺ and Eu³⁺ relative excitation. The Dy³⁺ excitation bands observed in the Dy³⁺/Eu³⁺ glass by monitoring the 611 nm Eu³⁺ emission, suggest that Dy³⁺ → Eu³⁺ energy transfer takes place, despite the fact that the Dy³⁺ emission decays in the Dy³⁺ and Dy³⁺/Eu³⁺ doped glass, remain without changes. The shortening of Eu³⁺ decay in presence of Dy³⁺ was attributed to an Eu³⁺ → Dy³⁺ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s⁻¹, respectively.     

Unexpected Luminescence Properties of Sr0.25Ba0.75Si2O2N2:Eu2+—A Narrow Blue Emitting Oxonitridosilicate with Cation Ordering

Owing to a parity allowed 4f⁶(⁷F)5d¹→4f⁷(⁸S_7/2) transition, powders of the nominal composition Sr_0.25Ba_0.75Si₂O₂N₂:Eu²⁺ (2 mol % Eu²⁺) show surprising intense blue emission (λ_em=472 nm) when excited by UV to blue radiation. Similarly to other phases in the system Sr_1?xBa_xSi₂O₂N₂:Eu²⁺, the described compound is a promising phosphor material for pc‐LED applications as well. The FWHM of the emission band is 37 nm, representing the smallest value found for blue emitting (oxo)nitridosilicates so far. A combination of electron and X‐ray diffraction methods was used to determine the crystal structure of Sr_0.25Ba_0.75Si₂O₂N₂:Eu²⁺. HRTEM images reveal the intergrowth of nanodomains with SrSi₂O₂N₂ and BaSi₂O₂N₂‐type structures, which leads to pronounced diffuse scattering. Taking into account the intergrowth, the structure of the BaSi₂O₂N₂‐type domains was refined on single‐crystal diffraction data. In contrast to coplanar metal atom layers which are located between layers of condensed SiON₃‐tetrahedra in pure BaSi₂O₂N₂, in Sr_0.25Ba_0.75Si₂O₂N₂:Eu²⁺ corrugated metal atom layers occur. HRTEM image simulations indicate cation ordering in the final structure model, which, in combination with the corrugated metal atom layers, explains the unexpected and excellent luminescence properties.     

Luminescence Tuning of Sr8MgCe(PO4)7:Eu2+,Mn2+ Phosphors: Structure Refinement,Site Occupancy,and Energy Transfer

Sr₈MgCe(PO₄)₇:Eu²⁺,Mn²⁺ phosphor with whitlockite‐type structure was prepared by a combustion‐assisted solid‐state reaction. The crystal structure and luminescence properties were investigated. Under UV radiation, Sr₈MgCe(PO₄)₇ host exhibits a violet‐blue emission band from Ce³⁺ ions. When Eu²⁺/Mn²⁺ are doped into the host, the samples excited with 270 nm UV radiation present multicolor emissions due to the energy transfer (ET) from Ce³⁺ to Eu²⁺/Mn²⁺. The emitting color of Sr₈MgCe(PO₄)₇:Eu²⁺ can be tuned from violet‐blue to yellow‐green, whereas Sr₈MgCe(PO₄)₇:Mn²⁺ can emit red light. Under excitation with long wavelength at 360 nm, Sr₈MgCe(PO₄)₇:Eu²⁺ phosphor shows a broadband emission from 390 to 700 nm, which is attributed to the 4f⁶5d¹→4f⁷ transition of Eu²⁺ without the contribution from Ce³⁺ emission. Tunable full‐color emitting light can be achieved in the Eu²⁺ and Mn²⁺‐codoped Sr₈MgCe(PO₄)₇ phosphor by ET_Eu–Mn through control of the levels of doped Eu²⁺ and Mn²⁺ ions. These results suggest that Sr₈MgCe(PO₄)₇:Eu²⁺,Mn²⁺ phosphor has potential applications in NUV chip pumped white LEDs.     

Luminescent Nitridophosphates CaP2N4:Eu2+, SrP2N4:Eu2+, BaP2N4:Eu2+, and BaSr2P6N12:Eu2+

Nitridophosphates MP₂N₄:Eu²⁺ (M=Ca, Sr, Ba) and BaSr₂P₆N₁₂:Eu²⁺ have been synthesized at elevated pressures and 1100–1300 °C starting from the corresponding azides and P₃N₅ with EuCl₂ as dopant. Addition of NH₄Cl as mineralizer allowed for the growth of single crystals. This led to the successful structure elucidation of a highly condensed nitridophosphate from single‐crystal X‐ray diffraction data (CaP₂N₄:Eu²⁺ (P6₃, no. 173), a=16.847(2), c=7.8592(16) Å, V=1931.7(6) ų, Z=24, 2033 observed reflections, 176 refined parameters, wR₂=0.096). Upon excitation by UV light, luminescence due to parity‐allowed 4f⁶(⁷F)5d¹→4f⁷(⁸S_7/2) transition was observed in the orange (CaP₂N₄:Eu²⁺, λ_max=575 nm), green (SrP₂N₄:Eu²⁺, λ_max=529 nm), and blue regions of the visible spectrum (BaSr₂P₆N₁₂:Eu²⁺ and BaP₂N₄:Eu²⁺, λ_max=450 and 460 nm, respectively). Thus, the emission wavelength decreases with increasing ionic radius of the alkaline‐earth ions. The corresponding full width at half maximum values (2240–2460 cm^?1) are comparable to those of other known Eu²⁺‐doped (oxo)nitrides emitting in the same region of the visible spectrum. Following recently described quaternary Ba₃P₅N₁₀Br:Eu²⁺, this investigation represents the first report on the luminescence of Eu²⁺‐doped ternary nitridophosphates. Similarly to nitridosilicates and related oxonitrides, Eu²⁺‐doped nitridophosphates may have the potential to be further developed into efficient light‐emitting diode phosphors.     

Eu2+ & Mn2+‐Coactivated Ba3Gd(PO4)3 Orange‐Yellow‐Emitting Phosphor with Tunable Color Tone for UV‐Excited White LEDs

A novel orange‐yellow‐emitting Ba₃Gd(PO₄)₃:x Eu²⁺,y Mn²⁺ phosphor is prepared by high‐temperature solid‐state reaction. The crystal structure of Ba₃Gd(PO₄)₃:0.005 Eu²⁺,0.04 Mn²⁺ is determined by Rietveld refinement analysis on powder X‐ray diffraction data, which shows that the cations are disordered on a single crystallographic site and the oxygen atoms are distributed over two partially occupied sites. The photoluminescence excitation spectra show that the developed phosphor has an efficient broad absorption band ranging from 230 to 420 nm, perfectly matching the characteristic emission of UV‐light emitting diode (LED) chips. The emission spectra show that the obtained phosphors possess tunable color emissions from yellowish‐green through yellow and ultimately to reddish‐orange by simply adjusting the Mn²⁺ content (y) in Ba₃Gd(PO₄)₃:0.005 Eu²⁺,y Mn²⁺ host. The tunable color emissions origin from the change in intensity between the 4f–5d transitions in the Eu²⁺ ions and the ⁴T₁‐⁶A₁ transitions of the Mn²⁺ ions through the energy transfer from the Eu²⁺ to the Mn²⁺ ions. In addition, the mechanism of the energy transfer between the Eu²⁺ and Mn²⁺ ions are also studied in terms of the Inokuti–Hirayama theoretical model. The present results indicate that this novel orange‐yellow‐emitting phosphor can be used as a potential candidate for the application in white LEDs.     

Investigation of Luminescence Properties of Eu3+, Dy3+ and Gd3+ Doped MgAl2Si2O8 Red‐emitting Phosphors

Rare‐earth‐doped aluminosilicates of alkaline earth MgAl₂Si₂O₈: Eu³⁺, Dy³⁺ and MgAl₂Si₂O₈: Eu³⁺, Gd³⁺ were synthesized by the solid state reaction method at 1300 ^oC. The phosphors were characterized by X‐ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). X‐ray powder diffraction studies show that the phosphors were crystallized in the triclinic crystal system. The phosphors show characteristic broad band phosphorescence of Eu³⁺. This broad band phosphorescence has red emission bands in the range of 580–705 nm corresponding to ⁵D₀ → ⁷F_j (j:0,2,3,4) transitions of Eu³⁺.     

Photoluminescence properties of rare earths (Eu3+, Tb3+, Dy3+ and Tm3+) activated NaInW2O8 wolframite host lattice

The photoluminescence (PL) studies on NaIn_1?xRE_xW₂O₈, with RE=Eu³⁺, Tb³⁺, Dy³⁺ and Tm³⁺ phases have shown that the relative contribution of the host lattice and of the intra-f–f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy³⁺ and Tm³⁺ activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu³⁺, with intense red emission, the host absorption is less pronounced and the intra-f–f transitions of the Eu³⁺ ions play a major role, whereas for Tb³⁺ intra-f–f transitions are only observed, giving rise to green emission.     

Kinetics and thermoluminescence glow curve study of Ba2MgSi2O7:Eu3+, Dy3+

This paper reports thermoluminescence glow curves of Eu³⁺, Dy³⁺-doped Ba₂MgSi₂O₇ phosphor for different UV exposure times. Kinetic data were evaluated by the peak-shape method. The glow curves shift toward higher intensity with increasing exposure time to UV at 365 nm. When the heating rate was 5 °C s^?1, peaks were observed at 101.76, 109.69, 102.67, and 104.05 °C, respectively, after UV exposure for 5, 10, 15, and 20 min. The glow peaks are indicative of second-order kinetics. Different kinetic data, i.e. trap depth, order of kinetics, activation energy, and frequency factor were also calculated. To evaluate the persistence characteristics of the luminescence of the phosphor, the lifetime of the charge in the trap was calculated; it was 348, 660, 368, and 428 s for UV exposure of 5, 10, 15, and 20 min, which indicates the luminescence of the phosphor is persistent.     

Enhanced photoluminescence of Ba2GdNbO6: Eu/Dy phosphors by Li doping

The Ba₂GdNbO₆: Eu³⁺/Dy³⁺ and Li⁺-doped Ba₂GdNbO₆: Eu³⁺/Dy³⁺ phosphors were prepared by solid-state reaction process. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) as well as lifetimes, was utilized to characterize the resulting phosphors. Under the excitation of ultraviolet light, the Ba₂GdNbO₆: Eu³⁺/Dy³⁺ and Li⁺-doped Ba₂GdNbO₆: Eu³⁺/Dy³⁺ show the characteristic emissions of Eu³⁺ (⁵D₀-⁷F_1,2,3 transitions dominated by ⁵D₀-⁷F₁ at 593 nm) and Dy³⁺ (⁴F_9/2-⁶H_15/2,_13/2 transitions dominated by ⁴F_9/2-⁶H_15/2 at 494 nm), respectively. The incorporation of Li⁺ ions into the Ba₂GdNbO₆: Eu³⁺/Dy³⁺ phosphors has enhanced the PL intensities depending on the doping concentration of Li⁺, and the highest emission was obtained in Ba₂Gd_0.9NbO₆: 0.10Eu³⁺, 0.01Li⁺ and Ba₂Gd_0.95NbO₆: 0.05Dy³⁺, 0.07Li⁺, respectively. An energy level diagram was proposed to explain the luminescence process in the phosphors.     

Thermoluminescent Properties of Tridymite SiO2 : Al3+, Eu3+

SiO₂ crystals have been used in electroluminescence devices and thermoluminescence (TL) dosimeters. However, their emission mechanisms have not yet been clearly explained. Recently, it has become possible to obtain amorphous, highly pure, SiO₂ prepared by the sol-gel method. The emission mechanism of TL was investigated using Al³⁺ and/or Eu³⁺-doped SiO₂ crystalline samples prepared by heat-treating under much lower temperature than the melting point of SiO₂. The TL spectrum of Eu³⁺-doped sample had main peaks due to the electron transitions from ⁵D₂ to ⁷F₅ (ca. 570 nm, yellow peak) and from ⁵D₀ to ⁷F₂ (ca. 610 nm, red peak). The yellow peak intensity has a maximum value in the SiO₂ doped with near 1 mmol% of Eu₂O₃, while the red peak intensity was almost constant. These facts suggest that bright yellow emission of SiO₂TL phosphor is synthesized by the diffusion of Eu³⁺ ion in SiO₂ matrix prepared by sol-gel method.     

Improved water resistance of SrAl2O4: Eu2+, Dy3+ phosphor directly achieved in a water-containing medium

In this paper, a heterogeneous precipitation method utilizing urea hydrolysis was adopted to coat a SiO₂ layer on the surface of SrAl₂O₄:Eu²⁺, Dy³⁺ long persistence phosphors. To avoid phosphor hydrolysis in a water-containing coating medium, the hydrolysis and polymerization reactions of tetraethyl orthosilicate (TEOS) were concerned and carried out. The crystal phases, surface morphologies, hydrolysis stability and water resistance on afterglow properties of coated phosphors were investigated. Scanning electron microscopy, energy dispersive spectrum analysis, transmission electron microscope and Fourier transform infrared spectrum results confirmed that a continuous, uniform and compact SiO₂ coating layer was successfully obtained on the phosphors surface. A theoretical coating amount of 5% or higher was found to be good for hydrolysis stability. Photoluminescence results revealed the coated phosphors showed much better water resistance on afterglow properties than the uncoated phosphor. We also discussed and proposed the hydrolysis restriction mechanism of SrAl₂O₄:Eu²⁺, Dy³⁺ in the water-containing coating medium.     

Research on Molecular Structure and Electronic Properties of Ln3+ (Ce3+, Tb3+, Pr3+)/Li+ and Eu2+ Co-Doped Sr2Si5N8 via DFT Calculation

We use density functional theory (DFT) to study the molecular structure and electronic band structure of Sr₂Si₅N₈:Eu²⁺ doped with trivalent lanthanides (Ln³⁺ = Ce³⁺, Tb³⁺, Pr³⁺). Li⁺ was used as a charge compensator for the charge imbalance caused by the partial replacement of Sr²⁺ by Ln³⁺. The doping of Ln lanthanide atom causes the structure of Sr₂Si₅N₈ lattice to shrink due to the smaller atomic radius of Ln³⁺ and Li⁺ compared to Sr²⁺. The doped structure’s formation energy indicates that the formation energy of Li⁺, which is used to compensate for the charge imbalance, is the lowest when the Sr2 site is doped. Thus, a suitable Li⁺ doping site for double-doped lanthanide ions can be provided. In Sr₂Si₅N₈:Eu²⁺, the doped Ce³⁺ can occupy partly the site of Sr₁²⁺ ([SrN₈]), while Eu²⁺ accounts for Sr₁²⁺ and Sr₂²⁺ ([SrN₁₀]). When the Pr³⁺ ion is selected as the dopant in Sr₂Si₅N₈:Eu²⁺, Pr³⁺ and Eu²⁺ would replace Sr₂²⁺ simultaneously. In this theoretical model, the replacement of Sr²⁺ by Tb³⁺ cannot exist reasonably. For the electronic structure, the energy level of Sr₂Si₅N₈:Eu²⁺/Li⁺ doped with Ce³⁺ and Pr³⁺ appears at the bottom of the conduction band or in the forbidden band, which reduces the energy bandgap of Sr₂Si₅N₈. We use DFT+U to adjust the lanthanide ion 4f energy level. The adjusted 4f-CBM of Ce_Sr1Li_Sr1-Sr₂Si₅N₈ is from 2.42 to 2.85 eV. The energy range of 4f-CBM in Pr_Sr1Li_Sr1-Sr₂Si₅N₈ is 2.75–2.99 eV and its peak is 2.90 eV; the addition of Ce³⁺ in Eu_Sr1Ce_Sr1Li_Sr1 made the 4f energy level of Eu²⁺ blue shift. The addition of Pr³⁺ in Eu_Sr2Pr_Sr2Li_Sr1 makes part of the Eu²⁺ 4f energy level blue shift. Eu²⁺ 4f energy level in Eu_Sr2Ce_Sr1Li_Sr1 is not in the forbidden band, so Eu²⁺ is not used as the emission center.     

Ba3P5N10Br:Eu2+: A Natural‐White‐Light Single Emitter with a Zeolite Structure Type

Illumination sources based on phosphor‐converted light emitting diode (pcLED) technology are nowadays of great relevance. In particular, illumination‐grade pcLEDs are attracting increasing attention. Regarding this, the application of a single warm‐white‐emitting phosphor could be of great advantage. Herein, we report the synthesis of a novel nitridophosphate zeolite Ba₃P₅N₁₀Br:Eu²⁺. Upon excitation by near‐UV light, natural‐white‐light luminescence was detected. The synthesis of Ba₃P₅N₁₀Br:Eu²⁺ was carried out using the multianvil technique. The crystal structure of Ba₃P₅N₁₀Br:Eu²⁺ was solved and refined by single‐crystal X‐ray diffraction analysis and confirmed by Rietveld refinement and FTIR spectroscopy. Furthermore, spectroscopic luminescence measurements were performed. Through the synthesis of Ba₃P₅N₁₀Br:Eu²⁺, we have shown the great potential of nitridophosphate zeolites to serve as high‐performance luminescence materials.     

Tunable luminescence and energy transfer process between Tb3+ and Eu3+ in GYAG:Bi3+, Tb3+, Eu3+ phosphors

A series of Eu³⁺ ions co-doped (Gd_0.9Y_0.1)₃Al₅O₁₂:Bi³⁺, Tb³⁺ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi³⁺, Tb³⁺, Eu³⁺ phosphors consists of broad bands in the shorter wavelength region due to 4f⁸ → 4f⁷5d¹ transition of Tb³⁺ ions overlapped with 6s² → 6s¹6p¹ (¹S₀ → ³P₁) transition of Bi³⁺ ions and the charge transfer band of Eu³⁺–O^2?. The present phosphors exhibit green and red colors due to ⁵D₄ → ⁷F₅ transition of Tb³⁺ ions and ⁵D₀ → ⁷F₁ transition of Eu³⁺ ions, respectively. The emission was shifted from green to red color by co-doping with Eu³⁺ ions, which indicate that the energy transfer probability from Tb³⁺ to Eu³⁺ ions are dependent strongly on the concentration of Eu³⁺ ions.