Single-doped Phosphors Research Articles

Modulation and Enhancement of Red Luminescence in Ca2GdSbO6: Eu3+ Phosphor by Co-Doping with Bi3.

The double perovskite structure of Ca2GdSbO6 as a fluorescent phosphor matrix material possesses a stable structure, making it an excellent candidate for a matrix material. In this study, single-doped Ca2GdSbO6: Eu3+ fluorescent phosphors and Bi3+ sensitized Ca2GdSbO6: Eu3+, Bi3+ fluorescent phosphor materials were synthesized using the high-temperature solid-state method. The luminescence of this phosphor is based on the 5D0→4F2 transition emission of Eu3+ ions, which occurs at 612nm. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra, high-temperature fluorescence spectra, and fluorescence decay lifetimes to study the phase structure, optical properties, crystal structure, and chemical purity of the samples. The performance of the single-doped phosphor was significantly improved by the addition of Bi3+ sensitizer. The luminescence intensity increased by nearly 100% compared to Ca2GdSbO6: Eu3+ phosphor, with a quantum efficiency increase of 124%. The thermal quenching activation energy was found to be 0.299eV, and the luminescence intensity remained at 70.3% of room temperature at 453K. These results indicate that the co-doping of Bi3+ has a modulation and enhancement effect on the luminescence of Ca2GdSbO6: Eu3+ red phosphor, showing great potential for application in near-ultraviolet-excited white LED devices.

Adjustable ultraviolet and white light dual emission phosphor Y2Sr(Ga1-yAly)4SiO12:xPr3+ for health lighting.

Mid-ultraviolet light (290-320 nm) can promote human vitamin D synthesis, which helps in the prevention and treatment of rickets and cartilage disease. For people who lack sufficient ultraviolet radiation all year round, it is significant to supplement the ultraviolet component in daily lighting sources. However, there are few luminous materials showing a combination of mid-ultraviolet light and white light emission on the market. Here, we designed a new material, Y2Sr(Ga1-yAly)4SiO12:xPr3+ (YSGAS:xPr3+), which achieves dual emission of 320 nm ultraviolet and white light from a single substrate with a single doped phosphor. Without Al3+ ions, the emission intensity of the Y2SrGa4SiO12:xPr3+ phosphor shows a contribution-dependent relationship, and concentration quenching due to exchange interaction. The crystal field environment was regulated by partially replacing Ga3+ ions with Al3+ ions. After introducing Al3+, YSGAS:xPr3+ phosphors exhibit dual ultraviolet emission (320 nm) and visible light emission. The emission color of YSGAS:xPr3+ can be adjusted by changing the Al3+ concentration, and Y2Sr(Ga0.6Al0.4)4SiO12:1%Pr3+ emits both ultraviolet light and white light. The LED device prepared by using the YSGAS:Pr3+ phosphor and chips shows a color temperature of 4858 K and appropriate CIE coordinates of (0.3474, 0.3390), indicating wide application prospects in the field of "health lighting" for particular populations.

Luminescence properties of Tb3+/Eu3+ ions activated LiLaSiO4 phosphors for solid-state lighting and flexible display applications

The synthesis and luminescence properties of Tb3+ and Eu3+ single- and co-doped LiLaSiO4 (LLSO) phosphors with energy transfer mechanisms were reported. The rare-earth ions doped LLSO phosphors were synthesized via a solid-state reaction method and their physical characterizations such as phase purity, surface morphology, and elemental analysis were investigated systematically. For the Tb3+ and Eu3+ single- and co-doped LLSO phosphors, their photoluminescence (PL) properties were studied in detail. The LLSO:Tb3+ and LLSO:Eu3+ single-doped phosphors showed superior red and green emissions due to 5D4→7F5 and 5D0→7F2 in the optimized characteristic electronic transitions under ultraviolet (UV) irradiation, respectively. The luminescence performances for both the LLSO:Tb3+ and LLSO:Eu3+ phosphors were optimized at 0.125 mol of doping ion concentration. Under UV excitation, by adjusting the Eu3+ ion concentration in LLSO:0.125Tb3+/Eu3+ phosphors, the tunable emissions from green to red via yellow-orange were obtained. Thus, the tunable emission spectra and luminescence decay lifetimes with increasing the doping content of acceptor ions (Eu3+) confirmed an efficient energy transfer from Tb3+ to Eu3+ ions in the co-doped samples. The critical distance between Tb3+ and Eu3+ was determined to be 13.26 Å and the energy transfer mechanism from Tb3+ to Eu3+ ions was demonstrated to be a dipole-dipole mechanism interaction. In addition, the temperature-dependent PL study was carried out for the LLSO:0.125Tb3+/0.025Eu3+ co-doped phosphor sample and it showed better thermal stability against the temperature quenching. The Tb3+ and Eu3+ single- and co-doped LLSO/polydimethylsiloxane (PDMS) flexible composite films were fabricated by mixing the phosphor powders and PDMS solution. Benefiting from the effective protection of the PDMS matrix, the luminescence stability of the composite films was greatly enhanced. Based on the excellent properties of the synthesized phosphors, Tb3+ and Eu3+ single-doped and Tb3+/Eu3+ co-doped LLSO phosphors could serve as a single-phase multicolor-emitting phosphor under UV excitations.

A novel Mn4+ -activated far-red Sr2 MgWO6 phosphor: synthesis, luminescence enhancement, and application prospect.

A novel far-red emitting phosphor Sr2 MgWO6 : Mn4+ was fabricated using high-temperature solid-state reaction. X-ray diffraction patterns, scanning electron microscopy images, and photoluminescence excitation and photoluminescence spectra for this phosphor were analyzed in detail. The analysis revealed that its emission ranged from 600 to 800 nm and peaked at 699 nm, which was attributed to the 2 Eg →4 A2g transition of Mn4+ under 314 nm excitation. Moreover, we introduced rare-earth Yb3+ ions into the Sr2 MgWO6 :Mn4+ to improve its far-red emitting intensity. The photoluminescence (PL) intensity of the Yb3+ co-doped phosphor was three times higher than that of the single-doped phosphor. Therefore charge compensation is an efficient approach to improving PL intensity. The phosphor emitted a far-red light that resembled the pigments essential for plant growth in terms of the absorption spectrum. Therefore, the obtained phosphor, Sr2 MgWO6 :0.006Mn4+ ,0.2Yb3+ , had the potential to be a new type of far-red luminescent powder for indoor plant growth LEDs.

Investigation of photoluminescence, thermoluminescence, and energy transfer mechanism in Ce/Dy co-doped Sr2Al2SiO7

In the present manuscript, we report the luminescence properties and energy transfer mechanism of Ce/Dy co-doped Sr2Al2SiO7 (SASO) phosphors prepared through the solid-state reaction method. Phase identification was done through a powder X-Ray diffraction tool and the obtained diffractogram confirms the formation of the desired phase. The Photoluminescence excitation and emission spectra of the prepared samples were investigated. Photoluminescence studies revealed that the luminescence intensity rises with increasing Dy concentration and optimized intensity was observed at 1 mol%. The energy transfer in the host has been attained successfully to produce color tunability. The Commission International de I'Eclairage (CIE) chromaticity coordinates and correlated color temperature (CCT) has been calculated. The energy transfer mechanism is further investigated via Thermoluminescence (TL) spectra. Further, the TL properties of synthesized phosphors were analyzed via the glow curve method along with varying UV doses. As compared to the single-doped phosphors, the TL glow curve indicates that very high intensity is observed at very low UV doses and the major TL peak is located in a higher temperature region. The calculated kinetic parameter indicates that Ce/Dy co-doped SASO has both shallow and deeper traps. All these findings suggest the potential applicability of synthesized phosphors as a low UV dosimeter.

Eu3+ Single-Doped Phosphor with Antithermal Quenching Behavior and Multicolor-Tunable Properties for Luminescence Thermometry

To date, non-contact luminescence thermometry methods based on fluorescence intensity ratio (FIR) technology have been studied extensively. However, designing phosphors with high relative sensitivity (Sr) has become a research hotspot. In this work, Eu3+ single-doped Ca2Sb2O7:Eu3+ phosphors with a high Sr value for dual-emitting-center luminescence thermometry are developed and proposed. The anti-thermal quenching behavior of Eu3+ originating from the energy transfer (ET) of host → Eu3+ is found and proved in the designed phosphors. Interestingly, adjustable color emission from blue to orange can be achieved. Surprisingly, the degree of the anti-thermal quenching behavior of Eu3+ gradually reduces from 240 to 127% as the Eu3+ doping content increases from 0.005 to 0.05 mol, attributed to most Eu3+ being located in the low symmetrical [Ca1O8] dodecahedral site. According to the differentiable responses of the host and Eu3+ to temperature, the maximal Sr value reaches 3.369% K-1 (383 K). Moreover, the ambient temperature can be intuitively predicted by observing the emitting color. Owing to the excellent performance in optical thermometry, color-tunable properties, and outstanding acid and alkali resistance for polydimethylsiloxane (PDMS) films, the developed Eu3+ single-doped Ca2Sb2O7:Eu3+ phosphors are expected to be prospective candidates in luminescence thermometers and LED devices in various conditions.

Color-tunable persistent luminescence in LiTa3O8 based phosphors for dynamic anticounterfeiting

Rare earth-doped persistent luminescent (PersL) phosphors are excellent candidates for anticounterfeiting due to their superior properties, including various luminescent colors, multifarious luminescent modes, and dynamic emission intensity. For classical PersL phosphors, single-doped phosphor always shows monotonous luminescent color in different emission modes, such as photoluminescence (PL) and PersL, which limits the anticounterfeiting level to a low degree. To optimize the optical properties of phosphors for anticounterfeiting applications, constructing multiactivator-doped phosphors with polychromatic luminescence emissions can be a feasible strategy in practical material development. In this study, a novel multicolor PersL material, Pr3+/Tb3+-doped LiTa3O8, was reported for the first time, where the PersL color of Pr3+ in LiTa3O8 host was red whereas terbium(III) (Tb3+) ions exhibited green PersL color. Two improvement strategies were implemented, including substitution of tin(IV) (Sn4+) and codoping with gadolinium(III) (Gd3+), to enhance PersL properties by regulating distribution of traps. Gd3+ codoping strategy effectively improved PersL intensity while the Sn substitution strategy increased the initial PersL intensity by four-fold and the duration prolonged by 2.5-fold. Based on the results of luminescent properties, a multicolor tunable PersL material, LiTa3O8:0.7 %Pr3+ 1 % Tb3+, was synthesized and conceptually designed into a multimode anticounterfeiting application. Based on this scheme, prototype anticounterfeiting devices were developed, which could display the anticounterfeiting patterns in both dynamic and static states. Thus, this study fabricated a novel PersL material with multicolor light in different luminescent modes, thus deepening the fundamental understanding of PersL materials and diversifying the potential candidates of optical anticounterfeiting materials.

Enhanced luminescence efficiency and thermal stability via introduction of non-rare earth Bi3+ in Gd5Si2BO13:Eu3+

A series of Gd5Si2BO13:Eu3+ and non-rare earth Bi3+ ions doped Gd5Si2BO13:Eu3+ phosphors was successfully synthesized via high-temperature solid-state method, and the as-obtained phosphors were studied on their phase structures, luminescence characteristics, thermal stability and luminescence lifetime. Transient fluorescence spectroscopy data show that the addition of Bi3+ can obviously enhance the emission intensity of Eu3+ in the near-ultraviolet band owing to energy transfer from Bi3+ to Eu3+. Besides, the addition of Bi3+ can improve the thermal stability of a single-doped phosphor Gd5Si2BO13:0.35Eu3+ from 70.33% to 87.45% at 150 °C and the quantum yield from 58.80% to 78.61% at room temperature. Finally, Gd5Si2BO13:Eu3+,Bi3+ was used to encapsulate white light-emitting diodes (WLEDs) with green ((Ba,Sr)2SiO4:Eu2+) and blue (BaMgAl10O17:Eu2+) commercial phosphors. The color rendering index of WLEDs was calculated to be larger than 90, and the color temperature was estimated to be 4300–4500 K, which demonstrate that Gd5Si2BO13:Eu3+,Bi3+ can be regarded as a red phosphor with great potential application. This paper can provide a new insight into design of high-efficiency phosphors by introducing non-rare earth Bi3+ ions via energy transfer from Bi3+ to Eu3+.

Up-conversion luminescence properties and temperature sensing performances of Ba5Y8Zn4O21:Yb3+, Er3+ phosphors

A serials of Er3+ single-doped and Yb3+, Er3+ co-doped Ba5Y8Zn4O21 phosphors were manufactured through high-temperature solid-state reaction technique to explore the application for optical thermometer. In the course of experiment, the samples were designed based on the orthogonal experimental method to find the optimal sample with the strongest green emission that can bring in high measurement accuracy. The relationship between doping content and luminescent intensity was systematically explored and the variation tendencies of green and red emission intensity were presented intuitively. Er3+ single-doped phosphors exhibit bright up-conversion emission under stimulation of 980 nm laser. With the addition of Yb3+, the characteristic emission intensity of Er3+ was greatly enhanced. Based on the luminescent features, the power dependent spectra and the energy structure of Yb3+ and Er3+, conceivable luminescent mechanism was deduced. Meanwhile, the temperature sensing behaviors were explored by the temperature dependent up-conversion spectra. The maximum relative sensitivity (SR) is 1.36 × 10−2 K−1 (at 293 K). The above investigations manifest that the Yb3+, Er3+ co-doped Ba5Y8Zn4O21 phosphors have potential applications for optical thermometer.

Construction of Novel Luminescent Thermometers Using Single-Doped Phosphors with Color-Tuning Properties

Construction of Novel Luminescent Thermometers Using Single-Doped Phosphors with Color-Tuning Properties

A Comparatitive Study on Photoluminescence and Color Propertites between Amorphous and Crystalline Organic-Inorganic Hybrids As Single-Phased and Single-Phased Phosphor for White-Light Emission

We have examined some zirconium organic complexes via an array of characterization techniques, showing that they are amorphous single-phased and single-doped phosphors for white-light emission. Combined with thermogravimetric measurement coupled with a quadrupole mass spectrometer, and inductively coupled plasma-atomic emission spectroscopy and/or mass spectrometry measurements, the detailed infrared spectroscopy analyses indicate that the amorphous phosphor is a sulphur species-doped zirconium oxy-hydroxyl acetate complex.The phosphors exhibit the photoluminescence and color properties comparable to or better than those of the crystalline metal-organic frameworks (MOFs). or organic-inorganic hybrid semiconductors for white-light emission.

Color-tunable Eu3+- or Sm3+-doped perovskite phosphors as optical temperature-sensing materials

Abstract Eu3+- or Sm3+-doped Sr2GaNbO6 perovskite phosphors are synthesized by a high-temperature solid-phase method, and their luminescence performance, energy transfer, and thermal sensitivity are studied. The results showed that Sr2GaNbO6 phosphor is an effective self-activated host, and successful doping with rare-earth ions is proven by their characteristic emission. At 332-nm excitation, both the broadband emissions from s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups and the sharp emissions from Eu3+ or Sm3+ ions are observed for Sr2GaNbO6:R3+ (R = Eu, Sm) phosphors, respectively. The emission color can be modulated from blue to white by regulating the doping concentration of Eu3+ or Sm3+, which is attributed to the effective energy transfer from s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups to Eu3+ or Sm3+. Based on the emission fluorescence intensity ratio of the s-orbital mixing of the transition metal ions Nb5+ and Sr2+ and GaO6 groups to the Eu3+ or Sm3+ ions in the range of 298–623 K, optical temperature sensing properties of Sr2GaNbO6:R3+ showed the maximum absolute and relative sensitivities are 0.0193 K−1 and 1.86% K−1 at 298 K of Sr2GaNbO6:0.018Eu3+ phosphor, respectively, as well as 0.00862 K–1 and 1.70% K−1 at 298 K and at 623 K, respectively, of Sr2GaNbO6:0.08Sm3+ phosphor. These results demonstrate a viable strategy to tune the emitting color and achieve optical temperature sensing in single-doped phosphors by controlling the energy transfer between the self-activated host and the activator. This strategy provides application potential for the white light-emitting diodes and non-contact thermometric multifunctional materials.

A novel single-phase Na3.6Y1.8(PO4)3:Bi3+,Eu3+ phosphor for tunable and white light emission

A new type of Bi3+,Eu3+ single- and co-doped Na3.6Y1.8(PO4)3 phosphate phosphors were manufactured using conventional high-temperature solid-state reaction technique to explore their application for solid-state lighting. The crystal structure, luminescent properties, luminescent mechanism and quantum efficiency were thoroughly explored. Results show that there are two crystallization sites for Bi3+ and Eu3+ ions. Upon the excitation of 342 and 373 nm, Bi3+ single-doped phosphors exhibit green and blue emission, derived from the 3P1 to 1S0 transition of Bi3+ located in different occupancy sites. Thanks to radiative energy transfer process from Bi3+ to Eu3+, adjustable emission could be acquired by altering Eu3+ content in co-doped phosphors. Pure white-light emission with quantum efficiency value of 22.9% can be realized in Na3.6Y1.8(PO4)3:0.01Bi3+,0.1Eu3+ sample and the integrated intensity of white light emission at 417 K remains 85% of that at room temperature. Our results indicate that Na3.6Y1.8(PO4)3:Bi3+,Eu3+ phosphors have feasible application in high-power ultraviolet driven solid-state lighting.

Multicolor emission leading by energy transfer between Dy3+ and Eu3+ in wolframite InNbTiO6

Exploring new color-tunable phosphors is of significance for light-emitting applications. In this work, multicolor-emitting InNbTiO6:Dy3+,Eu3+ phosphors were formulated and synthesized using the classic solid-state reaction technique. Phase identification indicates the pure wolframite crystal structure of as-prepared samples. According to the Rietveld refinement, dopants have been confirmed to occupy the In3+ site in the InNbTiO6 matrix. The phosphors exhibit strong absorption around 385 and 394 nm, due to the dominated transitions of 4F9/2->6H13/2 in Dy3+ and 5D0->7F2 in Eu3+, respectively, well matching the emissions from the commercial UV LED chips. In single doped phosphors, activators Dy3+ and Eu3+ under the UV light excitation respectively present their unique emission lines. As for the codoped phosphors, the co-activation and sensitization between Dy3+ and Eu3+ have been elucidated under a 394 nm excitation. The addition of Eu3+ into InNbTiO6:0.06Dy phosphor leads to the emission tuning from grass-green to orange-red crossing the warm-white region. The energy transfer can be proved through analyzing the PLE and PL profiles of the co-activated phosphors and evaluating the decay process for Dy3+ ions. According to the Dexter's theory and Reisfield's approximation, the mechanism of coupling effect has been identified to be the electric d-d (dipole-dipole) interaction. When the sum of dopants concentration equals to 0.09, the energy transfer efficiency reaches the maximum value 40.5. Moreover, the thermal stability of a representative InNbTiO6:0.06Dy3+,0.015Eu3+ phosphor have been investigated, which presented and a emission intensity maintenance of 42% at 423 K relative to room temperature 298 K. Besides, the quantum yields of InNbTiO6:0.06Dy3+, 0.04Eu3+ within the luminescence range 603–620 nm are measured to be 33.4% under the ultraviolet radiation of 394 nm. These results demonstrate that these new type phosphors have promising applications in UV LED based white light-emitting devices.

Broadband near-infrared luminescence and energy transfer of Cr3+, Ce3+ co-doped Ca2LuHf2Al3O12 phosphors

Broadband near-infrared phosphors are highly desirable for food testing. Targeted Ca2LuHf2Al3O12:Cr3+ (CLHA:Cr3+) and Ca2LuHf2Al3O12:Ce3+,Cr3+ (CLHA:Ce3+,Cr3+) phosphors were synthesized by the conventional high-temperature solid state reaction. The CLHA:Cr3+ phosphor, with a good thermal stability, shows a red shift owing to radiation reabsorption and non-radiative transition with increasing Cr3+ content. For co-doped sample, the emission intensity of Cr3+ can be enhanced by three times due to the energy transfer from Ce3+ to Cr3+, which can be evidenced by a significant overlap between the PLE of Cr3+ single-doped phosphor and the PL of Ce3+ single-doped phosphor. In addition, the mechanism of energy transfer is identified as a quadrupole-quadrupole interaction according to decay lifetime and Dexter's energy transfer formula. The broadband NIR emission peaked at 775 nm of CLHA:Cr3+,Ce3+ phosphor shows a bright prospect in nondestructive quality-control analysis systems for food.

Structure, energy transfer, and luminescence properties of NaLaMgWO6: Tb3+,Eu3+ phosphors for solid-state lighting

Novel NaLaMgWO6:Tb3+,Eu3+ phosphors with tunable color emissions were prepared by a solid-state reaction. The crystal structure, composition, and luminescent properties of the obtained phosphors were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and fluorescence spectrophotometer. The results reveal that NaLaMgWO6 crystallizes in a monoclinic double perovskite structure with C2/m space group. Tb3+ and Eu3+ single-doped phosphors show the intense green and red emissions at 545 and 617 nm, corresponding to the 5D4 → 7F5 transition of Tb3+ and the 5D0 → 7F2 transition of Eu3+, respectively, while for Tb3+ and Eu3+ co-doped phosphors, a tunable emission color from green to red is obtained by variation of the ratio of Eu3+ to Tb3+. The emission spectra and luminescence decay lifetimes verify the occurrence of energy transfer from Tb3+ to Eu3+ in NaLaMgWO6: Tb3+, Eu3+ phosphor, and the energy transfer mechanism is dominated by the dipole–quadrupole interaction. Furthermore, the thermal stability of NaLaMgWO6:Tb3+, Eu3+ phosphor was discussed from 305 to 515 K. The results exhibit the phosphors possess excellent thermal stability, and the activation energy is calculated to be 0.302 eV.

Modulating trap properties by Nd3+- Eu3+ co-doping in Sr2SnO4 host for optical information storage.

We report a novel Nd3+ and Eu3+ co-doped Sr2SnO4 (SSONE) phosphor showing the capability of "write-in" and "read-out" in optical information storage. As-prepared phosphors exhibit a dominant emission (PL) band centered at 596 nm under UV excitation, closely identical with its photo-stimulated luminescence (PSL) spectrum center (595 nm) upon near-infrared (NIR) light and thermal-stimulated luminescence (TSL) spectrum center (595 nm) under heat source. Remarkably, compared with Eu3+ single-doped phosphors, the co-doping strategy enhances the deep traps and also separates the deep traps with shallow traps, which are very crucial factors for optical information storage in electron trapping materials. Further, a demonstration confirmed the optical information storage capacity by photo- and thermal-stimulating the prepared phosphors filled in the designed patterns.

Luminescence and self-referenced optical temperature sensing performance in Ca2YZr2Al3O12:Bi3+,Eu3+ phosphors

Ca2YZr2Al3O12:Bi3+,Eu3+ phosphors were elaborated by a traditional solid-state reaction method. The luminescence of Ca2YZr2Al3O12:Bi3+ samples, energy transfer from Bi3+ to Eu3+, and the temperature sensing properties of Ca2YZr2Al3O12:Bi3+,Eu3+ samples have been systematically researched. Under the excitation of ultraviolet light, Bi3+ single doped phosphors give 313 and 392 nm emission bands, which origin from the substitutions of Bi3+ instead of Ca2+ and Y3+ sites, respectively. And the color-adjustable emission from blue to red were observed by increasing Eu3+ content in Ca2YZr2Al3O12:Bi3+,Eu3+ samples. Relying on different temperature dependent variation tendency, the fluorescence intensity ratio (FIR) values present outstanding temperature sensing properties. The absolute and relative sensitivity can be up to 0.826 %K-1 and 0.664 %K-1, respectively. All above results suggest that Ca2YZr2Al3O12:Bi3+,Eu3+ phosphor is a potential alternative for optical thermometer.

Na2Tb0.5(MoO4)(PO4):0.5Eu3+: A red-emitting phosphor with both high thermal stability and high colour purity

A novel red-emitting Na2Tb0.5(MoO4)(PO4):0.5Eu3+ phosphor was successfully synthesized via high temperature solid-state reaction method to explore new red emissions with high thermal stability and high colour purity. The results indicate that the alternating tetrahedrons of [PO4]3- and [MoO4]2- formed in the three-dimensional structure play a decisive role in isolating Tb3+ and Eu3+ ions. This structural isolation increases the concentration quenching of Tb3+ and Eu3+ in single-doped phosphors by more than 50%. In co-doped phosphors, the energy transfer from Tb3+ to Eu3+ was verified by the overlap of luminescent spectra and variations in decay curves. The emission colour of Na2Y1-x-y(MoO4)(PO4):yTb3+,xEu3+ can be tuned from green to red through the energy transfer process by adjusting the ratio of Tb3+/Eu3+. The emission intensity at 150 °C is 84.7% compared to room temperature, as well as the remarkable correlated colour temperature (2425 K) and high colour purity (95.3%) with CIE chromaticity coordinates (0.654, 0.345) make Na2Tb0.5(MoO4)(PO4):0.5Eu3+ as an incredible red-emitting phosphor for both display devices and warm white lighting applications.

Synthesis and luminescence properties of Eu3+ and Dy3+ ions single and co-doped Ba2LaV3O11 phosphors for white-light applications

We report the synthesis and luminescence properties of the rare-earth ions doped Ba2LaV3O11 phosphors. The Dy3+ and Eu3+ ions single doped and Dy3+/Eu3+ ions co-doped Ba2LaV3O11 phosphors were synthesized via a citrate-based sol-gel method. The surface morphology, phase purity, photoluminescence properties and thermal stability of the synthesized phosphors were determined from the X-ray diffractometer, field-emission scanning electron microscope and spectrofluorometer, respectively. The obtained results indicate that the prepared phosphor material was crystallized in monoclinic phase with the space group P21/c (14) and the diffraction peaks were well matched with the standard JCPDS (#40-0105) card values. Under charge transfer band excitation wavelengths, the Eu3+ (277 nm) and Dy3+ (274 nm) single doped phosphor samples exhibited characteristic red and yellow emissions, respectively. Meanwhile, the Dy3+/Eu3+ co-doped phosphor samples showed near white-light emission.