Temperature-dependent Emission Research Articles

Thermally stable illuminating characteristics of Tb3+/Sm3+ ions activated BaO–SrO–Al2O3–B2O3–SiO2 glasses for photonic applications

A set of Tb3+ and Tb3+/Sm3+ co-doped barium strontium aluminium borosilicate (BaSrAlBSi) glasses were produced to examine optical properties carefully. The transparent BaSrAlBSi glass amorphous nature was established by the XRD pattern. The absorption profile demonstrates the various peaks from n-UV to NIR range caused by the Tb3+ as well Sm3+ ions in BaSrAlBSi glass. BSi:Tb1.0 glasses give intense green emission under λex = 368 nm, BSi:Sm1.0 glasses exhibit the emission spectrum caused by the transitions of the Sm3+ ions. The Tb3+/Sm3+ co-doped BaSrAlBS glasses exhibit a mixture of emission exhibited by individual ions when excited at 368 nm, whereas it exhibits only red-orange light emission when excited under 402 nm. The PL lifetimes demonstrated a reduction in decay time as Sm3+ ions concentration increased in Tb3+ doped BaSrAlBSi glasses. CIE coordinates show the green emission was tuned towards the warm white region via co-doping of Sm3+ in Tb3+ doped BaSrAlBSi glasses. The strong thermal stability of BSi:TbSm1.0 glass is confirmed via a temperature-dependent emission profile. The observed results indicate that the transparent BSi:TbSm1.0 glasses as made will be directly useful for photonic device applications as n-UV pumping results in green warm white and orange emissions.

Parametric study of intensity-ratio-based phosphor thermometry using Mg4FGeO6:Mn4+ for instantaneous temperature measurement

Intensity-ratio-based phosphor thermometry is advantageous for instantaneous temperature measurement because it avoids interframe displacement due to moving phosphor coated samples that is encountered with lifetime-based methods. This study was aimed at investigating the effects of exposure time, excitation energy, and wavelength on intensity-ratio-based phosphor thermometry using Mg4FGeO6:Mn4+ (MFG). First, the temperature-dependent emission spectra of MFG were obtained under 355 nm and 405 nm excitations. The spectra exhibited different trends in the two cases, potentially because of thermally enhanced phonon-assisted absorption. Next, the shot-to-shot calibration uncertainties were evaluated from the temperature calibration results under different exposure time and excitation irradiance/fluence values for light-emitting diode/laser. The uncertainties under 355 nm and 405 nm excitations exhibited similar trends, i.e. they increased and decreased with increasing temperature and exposure time, respectively. For the minimum exposure time of 4 μs under 355 nm excitation, the uncertainty increased from 1.5 K at 323 K to 3.3 K at 673 K at a constant excitation fluence of 3.14 mJ cm−2. The uncertainties under 405 nm excitation were higher than those under 355 nm excitation. In addition, the inaccuracies due to excitation non-uniformity were evaluated from the calibration results under different excitation irradiance/fluence. The calibration curves were more sensitive to excitation irradiance at higher temperatures under 405 nm excitation. Consequently, the excitation non-uniformity induced inaccuracies under 405 nm excitation and different exposure time values were small at low temperatures (0.4–1.1 K at 323 K) and increased rapidly with temperature (2.6–14.4 K at 673 K). In the case of 355 nm excitation, the calibration curves exhibited small sensitivity to excitation fluence only at low temperatures. As the temperature increased, the inaccuracies under 355 nm excitation decreased and then increased, and exhibited values between 0.5 K and 2.5 K.

Mapping Temperature Heterogeneities during Catalytic CO2 Methanation with Operando Luminescence Thermometry.

Controlling and understanding reaction temperature variations in catalytic processes are crucial for assessing the performance of a catalyst material. Local temperature measurements are challenging, however. Luminescence thermometry is a promising remote-sensing tool, but it is cross-sensitive to the optical properties of a sample and other external parameters. In this work, we measure spatial variations in the local temperature on the micrometer length scale during carbon dioxide (CO2) methanation over a TiO2-supported Ni catalyst and link them to variations in catalytic performance. We extract local temperatures from the temperature-dependent emission of Y2O3:Nd3+ particles, which are mixed with the CO2 methanation catalyst. Scanning, where a near-infrared laser locally excites the emitting Nd3+ ions, produces a temperature map with a micrometer pixel size. We first designed the Y2O3:Nd3+ particles for optimal temperature precision and characterized cross-sensitivity of the measured signal to parameters other than temperature, such as light absorption by the blackened sample due to coke deposition at elevated temperatures. Introducing reaction gases causes a local temperature increase of the catalyst of on average 6-25 K, increasing with the reactor set temperature in the range of 550-640 K. Pixel-to-pixel variations in the temperature increase show a standard deviation of up to 1.5 K, which are attributed to local variations in the catalytic reaction rate. Mapping and understanding such temperature variations are crucial for the optimization of overall catalyst performance on the nano- and macroscopic scale.

Up-conversion phosphor Na2MoO4:Er3+/Yb3+ for the optical temperature sensing and anti-counterfeiting

Lanthanide-based upconversion (UC) materials exhibit remarkable temperature-sensing properties as excited by near-infrared light. This article aims to investigate the UC emission and its temperature-sensing behavior of Na2MoO4:Er3+/Yb3+. The molybdate powder Na2MoO4:Er3+, Yb3+ shows bright green UC emission under a 980 nm laser. By monitoring the temperature-dependent green emission, the optical thermometric properties of Na2MoO4:xEr3+/0.01 Yb3+ are investigated. 1.38% K−1 is the maximum absolute sensitivity (SA) and the relative sensitivity (SR) is 1.21% K−1 with a 0.09–0.22 K temperature resolution (ΔT) at 0.001Er3+. The material was successfully combined with acrylic to prepare invisible anti-counterfeit patterns. These significant findings provide a theoretical foundation for temperature-sensing capabilities and potential applications in anti-counterfeiting measures.

Origin of Eu2+/Eu3+ dual-fluorescence emission with temperature-dependency in borate glass containing Ca/SrAl2O4 crystals

At present, due to the existent trap levels, the investigation of the dual-fluorescence emission with temperature-dependency of Eu2+ and Eu3+ in long afterglow materials needs to be supplemented. In this work, Eu2+ and Eu3+ co-doped borate glass materials containing Ca/SrAl2O4 crystals are successfully prepared though solid phase melting method, presenting a temperature-dependent fluorescence emission changing from blue-violet to red-orange between 300 and 500K. This interesting finding is proved to be the different thermal quenching behavior caused by the varied luminescence transition mode of Eu2+ (440 nm) and Eu3+ (614 nm). Further, the instantaneous and the delayed trap carriers release is demonstrated to moderate the thermal quenching behavior, leading to better sensing performance at high temperatures in sample of more trap distribution, with Sr(max) being 1.3535% K−1 at 483K. Finally, good thermal cycling reversibility of the material shows that the temperature-dependent luminescence of Eu2+/Eu3+ assisted by traps is potential for optimizing the application of temperature sensing.

Synthesis, crystal structure, and characterizations of Eu3+-activated Ca2LnHf2(AlO4)3 (ln = Lu, Y and Gd) red-emitting phosphors for phosphors-converted white LEDs

High-brightness red-emitting Ca2LnHf2Al3O12:Eu3+ (Ln = Lu, Y and Gd) garnet phosphors with high photoluminescence efficiency are demonstrated for application in white light-emitting diodes (LEDs), and they have been successfully prepared using a high-temperature solid-state method. X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, photoluminescence excitation and photoluminescence spectra, decay lifetimes, photoluminescence quantum yield and temperature-dependent emission spectra have been used to characterize these samples. Under near-ultraviolet excitation into the 7F0→5L6 transition of Eu3+ at 394 nm, the Ca2LnHf2Al3O12:Eu3+ (Ln = Lu, Y and Gd) samples produce the characteristic red emissions of Eu3+ ions with peaks around 591, 611, 656, and 709 nm, corresponding to the 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions. These samples exhibit significant concentration-dependent luminescence behaviors, and the highest emission intensity is achieved at 50 mol% Eu3+ doping concentration owing to the concentration quenching effect caused by the dipole-dipole interaction between neighboring Eu3+ activators. The CIE color coordinates of these optimal Ca2LnHf2Al3O12:50%Eu3+ (Ln = Lu, Y and Gd) phosphors are (0.6339, 0.3654), (0.6341, 0.3653), and (0.6343, 0.3651), along with respective color purity of 92.4%, 92.6%, and 92.6%. The photoluminescence quantum yields of Ca2LnHf2Al3O12:50%Eu3+ are determined to be 39.2%, 56.6%, and 53.3% for Ln = Lu, Y, Gd, respectively. A white LED device has been fabricated through utilizing the Ca2YHf2Al3O12:50%Eu3+ phosphor as red-emitting color converter, which generates bright warm-white light with high color rendering index (80.8), low correlated color temperature (3920 K), CIE chromaticity coordinates (0.3827, 0.3742), and high luminous efficacy (11.56 lmW−1) under 40 mA driving current.

High-color-quality blue-light-pumped full-spectrum white-light-emitting diodes realized by efficient green-emitting CaY2HfScAl3O12:Ce3+ phosphors

Rare-earth doped inorganic phosphors are critical for solid-state white lighting. Particularly, efficient broadband, blue-light-excitable, green-emitting phosphors are highly needed for fabricating full-spectrum white-light-emitting diodes (WLEDs) with high-color-quality. Herein, we describe a new efficient blue-light-excited CaY2HfScAl3O12:Ce3+ green phosphor with high quantum efficiency (QE) and broad emission bandwidth. X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometer, excitation and emission spectra, CIE color coordinates, QE values, and temperature-dependent emission spectra have been used to characterize the samples. Rietveld refinement reveals that the CaY2HfScAl3O12 garnet compound has a cubic structure with lattice parameters of a = b = c = 12.38(13) Å, α = β = γ = 90°, and V = 1897.85(6) Å3. Impressively, the Ce3+ ions in the CaY2HfScAl3O12 host exhibit broadband excitation bands in the 300–500 nm spectral range with a maximum at 450 nm. Upon 450 nm excitation, the optimal phosphor doped with 2 mol% Ce3+ shows a broad green emission band in the wavelength range of 460–750 nm peaking around 532 nm, along with full width at half maximum of 121 nm as well as high internal QE of 78.9% and external QE of 46.6%. Ce3+ concentration-dependent luminescence properties and thermal stability at elevated temperature have been comprehensively studied. Finally, a WLED device is fabricated by utilizing CaY2HfScAl3O12:Ce3+ green phosphor, CaAlSiN3:Eu2+ red phosphor and a 450 nm blue LED chip, which generates bright full-spectrum warm-white light with ultrahigh color rendering index (Ra = 98.0, R9 = 97.5) and low correlated color temperature of 3602 K under 180 mA drive current. This work provides new insights into designing and developing efficient green phosphors for full-spectrum LED lighting.

Multiple Triplet Metal-Centered Jahn-Teller Isomers Determine Temperature-Dependent Luminescence Lifetimes in [Ru(bpy)3 ]2.

Understanding the factors that determine the luminescence lifetime of transition metal compounds is key for applications in photocatalysis and photodynamic therapy. Here we show that for (bpy = 2,2'-bipyridine), the generally accepted idea that emission lifetimes can be controlled optimizing the energy barrier from the emissive triplet metal-to-ligand charge-transfer (3 MLCT) state to the thermally-activated triplet metal-centered (3 MC) state or the energy gap between both states is a misconception. Further, we demonstrate that considering a single relaxation pathway determined from the minimum that is lowest in energy leads to wrong temperature-dependent emission lifetimes predictions. Instead, we obtain excellent agreement with experimental temperature-dependent lifetimes when an extended kinetic model that includes all the pathways related to multiple Jahn-Teller isomers and their effective reaction barriers is employed. These concepts are essential to correctly design other luminescent transition metal complexes with tailored emission lifetimes based on theoretical predictions.

Optical temperature-sensing properties of trivalent europium with high sensitivities in a wide temperature range

To develop new luminescent materials for optical thermometer, the Eu3+-activated BaY2ZnO5 (BYZ) phosphors were designed. Upon 394 nm excitation, several groups of 5D0-2→7FJ (J = 0–4) transitions are observed, and the dominant emission is located at 625 nm. The temperature-dependent emission spectra reveal that the emission peaks are weakened with different rates, depending on the excited states of Eu3+. The transient decay kinetics, studied at various temperatures, are in agreement with the emission spectral features. The optical temperature-sensing performance is evaluated with two strategies. For the thermally-coupled (TC) levels of Eu3+, the fluorescence intensity ratio (FIR) of the 536 and 593 nm emissions follows the Boltzmann distribution, and the sensor sensitivities rise with increasing temperature. For the non-TC levels of 5D0 and 5D2, the piecewise functions between the FIRs and absolute temperature are utilized, and the highest absolute and relative sensitivities in the BYZ:7%Eu3+ phosphor are obtained to be 0.674 and 2.19% K−1 at 533 K, respectively. Thus, the developed samples can show higher sensitivities at higher temperature.

Temperature-dependent THz properties and emission of organic crystal BNA.

As high-average power ultrafast lasers become increasingly available for nonlinear conversion, the temperature dependence of the material properties of nonlinear crystals becomes increasingly relevant. Here, we present temperature-dependent THz complex refractive index measurements of the organic crystal BNA over a wide range of temperatures from 300 K down to 80 K for THz frequencies up to 4 THz for the first time. Our measurements show that whereas the temperature-dependent refractive index has only minor deviation from room temperature values, the temperature-dependent absorption coefficient decreases at low temperature (-24% from 300 K to 80 K). We additionally compare these measurements with conversion efficiency and spectra observed during THz generation experiments using the same crystal actively cooled in the same temperature range, using an ultrafast Yb-laser for excitation. Surprisingly, the damage threshold of the material does not improve significantly upon active cooling, pointing to a nonlinear absorption mechanism being responsible for damage. However, we observe a significant increase in THz yield (+23%) at lower temperatures, which is most likely due to the reduced THz absorption. These first findings will be useful for future designs of high-average power pumped organic-crystal based THz-TDS systems.

“Double-high” field electron emission of screen-printed carbon nanotube cathodes

High performance cold cathodes based on carbon nanotubes (CNTs) are fabricated by using a screen-printing method. The CNT cathode shows stable electron emission with no significant deterioration and the temperature-dependent emission has been also investigated. The results demonstrate that the maximum emission current of CNT emitters can be reached to 16.9 mA at electric field of 7.6 V μm−1, corresponding to super-high current density of 562 mA cm−2 under continuous driving mode. Under pulse driving mode, the peak current of 70 mA with a high current density of 2333 mA cm−2 is further obtained at electric field of 11.5 V μm−1. The presented CNT emitters display high electron emission both in total current and current density under continuous and pulse driving modes. This work will open a new avenue towards designing “double-high” CNT cold electron sources for broad application prospects in vacuum electronic devices requiring high current and density simultaneously.

Photoluminescence of Eu3+ in silicate-based phosphors by near-infrared and near-ultraviolet excitation for multifunctional applications

In this work, a series of Eu3+/Yb3+ doped La1.55SiO4.33 (LSO) phosphors were prepared by solid state reaction method for multifunctional applications. The phase purity and particle morphology were characterized with XRD and SEM technique, respectively. Upon ultraviolet light excitation, the downshifting luminescence of Eu3+ was observed in the red region, and the strongest emission peak located at 612 nm is attributed to the forced electric dipole 5D0→7F2 transition. The optimal Eu3+ doping concentration was determined to be 20 mol%, for which the internal quantum efficiency of the phosphor reaches 75.1%. The temperature-dependent emission spectra of LSO:20%Eu3+ revealed that the quenching temperature T0.5 is 483 K. For the upconversion (UC) luminescence, the Yb3+-Eu3+ codoped LSO phosphors were designed, where the Yb3+ ion was used as a sensitizer. The UC mechanism for a cooperative energy transfer was learnt from the pump-power-dependent emission spectra. By excitation at various temperatures, the intensities of emissions from different excited states showed different changes with temperature. All the above spectral characteristics indicate that the LSO:Eu3+/Yb3+ phosphors can show potential applications in LEDs, anticounterfeiting and optical thermometer.

Radiative Heat Transfer in Models of DC Arc Plasma

The radiative heat transfer in arc plasma models of a free-burning arc and a plasma torch in atmospheric pressure argon is taken into account in a self-consistent way. This is realized by the P1 method for solving the equation of radiative transfer and the multi-band approximation that considers the division of the emitted spectrum into a number of spectral bands. Net emission coefficients are evaluated by solving the equation of radiative transfer in three dimensions in an isothermal cylindrical plasma. The arc plasma parameters of the free-burning arc and the plasma torch obtained accounting for radiative transport have been compared with those from the temperature-dependent net emission coefficient for a radius of 1 mm. The results show that in general, the models applying the net emission coefficient provide results in the arc core close to that using the P1 method. The discrepancy is stronger in the arc periphery and near walls, where the P1 method predicts absorption of radiation.

The effect of boron and scandium doping on the luminescence of LuAG:Ce and GdAG:Ce for application as scintillators

This study concerns cerium and boron doped Lu3Al4Sc1O12 and Gd3Al3Sc2O12 garnet µ-crystalline powders, which were synthesized for the first time. Rare earth ion, particularly Ce3+ activated garnets, due to their high density and efficient Ce3+ luminescence upon blue, UV, or x-ray excitation, can be used as scintillators that convert high-energy radiation into visible light. The incorporation of B3+ and Sc3+ ions into the garnet matrix corresponds to the improvement of the scintillating properties. Boron in these compounds could act like a flux and thus modulate particle morphology, while scandium solely changes the physical and luminescent properties of these garnets. From the measured radioluminescence emission spectra, it could be concluded that boron doping results in a higher emission intensity when the compounds are excited by high-energy radiation. The most striking effect is that the decay time is reduced, and the quantum efficiency of the compounds increases. After improving the kinetic properties of these compounds, it is possible to discuss a wider application of the synthesized materials. In addition to the aforementioned properties, room temperature as well as temperature dependent photoluminescence emission, excitation, and decay times at different temperatures were taken for all samples. The elemental composition of the samples was determined by using the ICP-OES technique. The crystal structure was analyzed by means of powder XRD. Particle morphology and size distribution were also investigated.The main idea of this research is to synthesize new and adjusted garnet type compounds that show better luminescent properties, which are required for scintillator materials.

Achieving Highly Efficient Warm-White Light Emission in All-Inorganic Copper-Silver Halides via Structural Regulation.

Single-component metal halides with white light emission are highly attractive for solid-state lighting applications, but it is still challenging to develop all-inorganic lead-free metal halides with high white-light emission efficiency. Herein, by rationally introducing silver (Ag) into zero-dimensional (0D) Cs3 Cu2 Br5 as new structural building unit, a one-dimensional (1D) bimetallic halide Cs6 Cu3 AgBr10 is designed that emits strong warm-white light with an impressive photoluminescence quantum yield (PLQY) of 94.5% and excellent stability. This structural transformation lowers the conduction band minimum while maintaining the localized nature of the valence band maximum, which is crucial in expanding the excitation spectrum and obtaining efficient self-trapped excitons (STEs) emission simultaneously. Detailed spectroscopy studies reveal that the white-light originates from triplet STEs emission, which can be remarkably improved by weakening the strong electron-phonon coupling and thus suppressing phonon-induced non-radiative processes. Moreover, the interesting temperature-dependent emission behavior, together with self-absorption-free property, make Cs6 Cu3 AgBr10 as sensitive luminescent thermometer and high-performance X-ray scintillator, respectively. These findings demonstrate a general approach to achieving effective single-component white-light emitters based on lead-free, all-inorganic metal halides, thereby opening up a new avenue to explore their versatile applications such as lighting, temperature detection and X-ray imaging.

Luminescence properties of Eu2+/3+ co-activated La6Sr4(SiO4)6F2 polychromatic phosphors towards white light-emitting diodes and anti-counterfeiting

To obtain emitting color regulation, series of Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors were synthesized. The crystal structure, morphology, elemental compositions and luminescence performances of the final products were discussed. Excited by 365 nm, all of the studied samples can emit the characteristic emissions of Eu2+ and Eu3+, in which their fluorescence intensities have various responses to doping content. Specially, as the dopant content increases, the emitting color is changed from green to yellow. Moreover, via changing the excitation wavelength, tunable emissions are also realized in the studied samples. On the basis of the temperature dependent emission spectra, it is found that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors possess good thermal stability. Through selecting the designed phosphors as yellow emitting components, a warm white light-emitting diode (white-LED) was packaged, in which its electroluminescence properties are hardly altered at high injection current. When the working current is 100 mA, the color coordinate, correlated color temperature and color rendering index of the fabricated white-LED are (0.358,0.358), 4580 K and 87.39, respectively. In addition, using the resultant compounds as luminescent labels, different patterns were prepared for the application in information encryption. The results demonstrated that Eu2+/3+-coactivated La6Sr4(SiO4)6F2 phosphors with multicolor emissions and outstanding thermal stability are suitable for white-LED and optical anti-counterfeiting as emitting components.

Three novel Mn2+-based halides: Heat/acid-induced structural transformation and luminescent conversion

Mn2+-based halides show great promise for solid-state lighting and display applications owing to their structural flexibility and excellent luminescence properties. Herein, three hybrid manganese halides (N-AEP)[MnBr3(H2O)3]2·Br (1), [(N-AEP)2MnBr6]·2Br (2) and [(N-AEP)2MnBr4]·3Br(H2O) (3) with the same organic ligand have been successfully synthesized by adjusting various HBr level or temperature of growth solutions. Systematic characterizations of halides including crystal structure, thermal and photophysical properties were carried out. Their distinct inorganic groups lead to the various luminescence colors: purple-red light in 1, orange-red light in 2 and green light in 3. Some interesting physicochemical features, for 1 the temperature-dependent emission properties, 2 the satisfactory thermostability with higher PLQY (13.36%), and 3 the weak ferromagnetic coupling effect, broaden their application prospects. This paper offers sufficient synthetic experiences for Mn2+-based halides with different inorganic groups in detail, and provides a reasonable research scheme for their optical properties.

A high-precision thermometry strategy by replacing the infrared with visible light for detection.

We have developed a high-precision thermometry strategy based on 4I9/2-4I15/2 (I800 nm) and 4S3/2-4I15/2 (I551 nm) transitions of Er3+, after replacing the measurement of the 4I11/2-4I15/2 (I1000 nm) transition with the 4S3/2-4I15/2 transition, i.e., using visible light for detection instead of infrared. Through rate equation model analysis, (I1000 nm)2 and I551 nm can be substituted for each other under certain conditions. Further, because the 4I9/2 and 4I11/2 levels of Er3+ are thermally coupled, a new idea of ratiometric thermometry is proposed based on the ratio of (I800 nm)2 and I551 nm, which has the advantages of anti-interference of excitation light source fluctuation and background-free detection. The feasibility of the idea was verified by researching the power-dependent emission spectra at different temperatures and temperature-dependent emission spectra of a CaWO4:Er3+,Yb3+ sample under 980-nm laser excitation. The maximum relative sensitivity for the new ratiometric thermometry reaches up to 7.4% K-1 and the optimal temperature uncertainty calculated is 0.03 K at 303 K. This study provides guidance for solving the problem of a weak response of an infrared detector.

Highly symmetric lattice environment induced orange-red emitting of Eu3+ in a novel tungstate phosphor with broad-band ultraviolet excitation

In this work, we reported the synthesis and characteristic luminescence of an orange-red emitting phosphor NaBa10Y5W4O30: Eu3+ for ultra-violet white light emitting diodes. The phase compound, crystalline structure and morphology are analyzed. The results indicate that a heavy doping of Eu3+ (x = 50%) is realized in NaBa10Y5-5xW4O30: xEu3+ without any impurity phase. Moreover, the optical band gap is analyzed by diffuse reflectance spectroscopy and further confirmed by density function theory (DFT). Meanwhile, the as-synthesized NaBa10Y5W4O30: Eu3+ phosphor can be efficiently pumped by strong broad-band excitation around 315 nm due to the charge transfer transition from [WO6]6- groups to Eu3+. Owing to the highly symmetric lattice environment of Eu3+ in YO6 sites, a strong orange-red emission at 596 nm with color purity of 95.34% is obtained, corresponding to the 5D0→7F1 magnetic dipole transition of Eu3+ ions. The critical concentration is obtained to be x = 15%, and the quenching mechanism is discussed to be dipole–dipole interaction. Furthermore, the temperature dependent emission behavior are analyzed, and the thermal quenching mechanism are explained by the variable temperature decay curve and configuration coordination diagram. Finally, an orange-red light emitting diode lamp is fabricated based on NaBa10Y5W4O30: 15%Eu3+ phosphor and 315 nm semiconductor chip. In summary, the results indicate that NaBa10Y5W4O30: Eu3+ phosphor has the potential to be an orange-red phosphor for white light emitting diodes.

Luminescence Performance of Mn4+ Activated BaLa2Al2O7 Phosphors

Mn4+ doped BaLa2Al2O7 phosphors were developed after a sintering process at 1400 °C for 3 h. The phase and luminescence performance of them were researched. The XRD patterns confirm single phase of the Mn4+ doped BaLa2Al2O7 phosphors. Upon the UV light excitation, the Mn4+ doped BaLa2Al2O7 phosphors emit strong deep-red emission. The concentration-dependence emission spectra demonstrate that the critical concentration for Mn4+ ion in BaLa2Al2O7 host is 0.006. On the basis of the temperature-dependence emission spectra, the activation energy for Mn4+ has been calculated as 0.292 eV, which suggests excellent thermostability of the Mn4+ activated BaLa2Al2O7 phosphors.