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The white-light-emitting devices (WLEDs) for urban ecological lighting remain the challenge. The current urban lighting system destroys the growth habits of plants and leads to inhibition of plant growth, reduced branching, smaller leaf area and reduced total dry weight due to excessive blue light. In this work, a series of blue-green and red dual-emission Na 3 Ba 2 Ca(PO 4) 3 :Eu2+, Mn2+ phosphors have been successfully synthesized by the high-temperature solid-state reaction method. The crystal structure, the occupancy of the dopant ions and the luminescence characteristics were carefully investigated. The excitation and emission spectra as well as the decay lifetime confirm the effective energy transfer from Eu2+ to Mn2+, which leads to a tunable luminescence with greatly reduced blue emission. Especially, the optimal Na 3 Ba 2 Ca(PO 4) 3 :0.02Eu2+, 0.11Mn2+ phosphor demonstrates a high internal quantum yield of 99.7%. At 150 °C, the luminescence intensity of Na 3 Ba 2 Ca(PO 4) 3 :0.02Eu2+, 0.11Mn2+ can maintain 64.5% of room temperature intensity. In addition, the WLED device fabricated with Na 3 Ba 2 Ca(PO 4) 3 :Eu2+, Mn2+ phosphor shows white light emission with CIE coordinates of (0.3800, 0.3852), rendering index (Ra) of 65.4 and correlated color temperature (CCT) of 3640 K. These results confirm that the Na 3 Ba 2 Ca(PO 4) 3 :Eu2+, Mn2+ phosphor can be applied as a white light source in the urban ecological field. [Display omitted] • Tunable white Na 3 Ba 2 Ca(PO 4) 3 :Eu2+,Mn2+ were synthesized for the first time. • Occupancy of dopant ions in the matrix is fully analyzed. • The conversion mechanisms are described as cooperative energy transfers from Eu2+ to Mn2+. • The Na 3 Ba 2 Ca(PO 4) 3 :0.02Eu2+,0.11Mn2+ owns high internal quantum yield and urban ecological lighting. • This phosphor can be applied as a white light source in the urban ecological field. [ABSTRACT FROM AUTHOR]

During the process of developing commercial chips, the phosphors with single broadband emission are indispensable. In this report, a new ternary phosphate phosphor Na 3 Ba 2 Ca(PO 4) 3 :Eu2+ has been successfully synthesized by the high-temperature solid-state reaction (HSSR) method, which shows broad emitting band in the range of 350–600 nm centered at 436 nm (FWHM ∼ 72.3 nm). The crystal structure of the Na 3 Ba 2 Ca(PO 4) 3 and Eu2+ doped Na 3 Ba 2 Ca(PO 4) 3 were determined by the Rietveld method, indicating the trigonal system with P 31 c space group. The selective two-site occupancy tendency of Eu2+ ions at Ba1O 9 and Ca2O 8 sites in the matrix was comprehensively revealed according to the split peaks (433 nm and 469 nm) at 298 K and 11 K, computational validation and fluorescence lifetime analysis of photoluminescence spectrum. Impressively, the optimal Na 3 Ba 2 Ca(PO 4) 3 :0.02Eu2+ phosphor exhibits appropriate spectrum resemblance (SR) indexes (58.5% and 72.2%), proper thermostability (78.6%) and excellent chromaticity stability (Δ x = 8.68 × 10−6 and Δ y = 3.64 × 10−5). Besides, the phosphor prepared by HSSR owns the higher internal quantum efficiency of 62.1% in comparison with that synthesized by polymerizable complex (PC) method. The new phosphor can serve as a potential broadband and blue-emitting phosphor for the application of solid-state lighting and plant growth. [Display omitted] • First synthesis of Eu2+ ion doped Na 3 Ba 2 Ca(PO 4) 3 phosphor by high temperature solid phase method. • The internal quantum efficiency of phosphor prepared in this work is 9 times of polymerizable complex (PC) method. • Two site-occupancy of Eu2+ in host was carefully determined. • The Na 3 Ba 2 Ca(PO 4) 3 : 0.02Eu2+ owns good thermostability and chromaticity stability. [ABSTRACT FROM AUTHOR]

The new dual-emitting and color tunable single phase of Na 2 BaSr(PO 4) 2 :0.03Eu2+, x Mn2+ (NBSP:0.03Eu2+, x Mn2+) phosphor are successful prepared in this work. The phase purity and photoluminescence properties are investigated. Regarding to the coordination, valence and cation radius, the Eu2+ ions occupy the Sr2 and Sr3 site and Mn2+ ions occupy the Sr3 site. According to the photoluminescence (PL) spectra of NBSP:0.03Eu2+, x Mn2+ (x = 0–0.09), the strong energy transfer (ET) between Eu2+ and Mn2+ exists in these phosphors. The strong ET efficiency from Eu2+ to Mn2+ is as high as 92%, while the ET mechanism of Eu2+ and Mn2+ is quadrupole-quadrupole interaction. Moreover, the CIE coordinate of Eu2+ and Mn2+ co-doped Na 2 BaSr(PO 4) 2 phosphors can realize the color tunable emission from blue to cold white. The temperature dependent photoluminescence intensity of NBSP:0.03Eu2+, 0.05Mn2+ phosphor still keeps 75.8% of that initial intensity when the temperature is 150 °C. In summary, the NBSP:0.03Eu2+, x Mn2+ phosphors have a promising application in white light LED. [Display omitted] • A series of NBSP:0.03Eu2+, x Mn2+ (x = 0–0.09) phosphors have been synthesized. • The strong energy transfer efficiency from Eu2+ to Mn2+ is as high as 92% in those phosphors. • The temperature dependent emission still keeps 75.8% of initial intensity at 150 °C in NBSP:0.03Eu2+, 0.05Mn2+ phosphor. • Realizing the color tunable emission from blue to cold white by co-doped Eu2+, Mn2+ into NBSP phosphor. [ABSTRACT FROM AUTHOR]

The development of novel single-component white-emitting phosphors with high thermal stability is essential for improving the illumination quality of white light-emitting diodes. In this work, we synthesized a series of Ce3+, Tb3+, Mn2+ single- and multiple-doped Ca 9 La(PO 4) 7 (CLPO) phosphors with β-Ca 3 (PO 4) 2 -type structure by the simple high-temperature solid-state reaction. The crystallization behavior, crystal structure, surface morphology, photoluminescence performance, decay lifetime and thermal stability were systematically investigated. The PL spectra and decay curves have evidenced the efficient energy transfer from Ce3+ to Tb3+ and from Ce3+ to Mn2+ in the CLPO host, and corresponding energy transfer efficiency reaches 41.8% and 54.1%, respectively. The energy transfer process of Ce3+→Tb3+ and Ce3+→Mn2+ can be deduced to the resonant type via dipole-dipole and dipole-quadrupole interaction mechanism, and corresponding critical distance were determined to be 12.23 and 14.4 Å, respectively. Based on the efficient energy transfer, the white light emission can be successfully achieved in the single-component CLPO:0.15Ce3+, 0.10Tb3+, 0.04Mn2+ phosphor, which owns CIE chromaticity coordinates of (0.3245, 0.3347), CCT of 5878 K, internal and external quantum efficiency of 84.51% and 69.32%. Especially, compared with the emission intensity at 25 °C, it still remains 98.5% at 150 °C and 92.0% at 300 °C. Based on these results, the single-component white light emission phosphor CLPO:0.15Ce3+, 0.10Tb3+, 0.04Mn2+ is a potential candidate for UV-converted white LEDs. [ABSTRACT FROM AUTHOR]

Using functional phosphors that have a range of benefits, such as quick response to n-UV/blue light excitation, high quantum efficiency and low thermal quenching is crucial. In this work, we have utilized the traditional high-temperature solid-state reaction to synthesized Ce3+, Tb3+ single- and co-doped KBaBP 2 O 8 (KBBPO) phosphors. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the luminescence properties and energy transfer process from Ce3+ to Tb3+ were investigated in details. Due to the Ce3+ can adequately sensitize Tb3+, the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The emission color chromaticity for the various KBBPO phosphors varies from dark blue to bright green with the increased concentration of Tb3+. The energy transfer mechanism between Ce3+ and Tb3+ is dominated by the exchange interaction, while the efficiency of the energy transfer is calculated as 59.29%. The optimal KBaBP 2 O 8 : 0.02Ce3+, 0.05 Tb3+ phosphor demonstrated low thermal quenching, which only reduces 19.3% of the initial intensity at 150 °C. The new KBaBP 2 O 8 : Ce3+, Tb3+ phosphor will be a potential candidate for wide-color-gamut display backlights. [Display omitted] • A series of Ce3+, Tb3+ co-doped KBaBP 2 O 8 phosphors have been synthesized. • The energy transfer efficiency from Ce3+ to Tb3+ can reach to 59.29% in Ce3+, Tb3+ co-doped KBaBP 2 O 8 phosphors. • The emission color can be tuned from blue to green by co-doped Ce3+ and Tb3+ into KBaBP 2 O 8 host. • Compared with the emission intensity at 25 °C, the overall emission intensity still remains 80.7% at 150 °C. [ABSTRACT FROM AUTHOR]

Exploring for red-emitting phosphor materials with supper property plays a key role in the development of white light-emitting diodes (WLEDs). Simultaneously, the crystal structure has a crucial effect on its luminescence properties. In this work, we synthesized a type of new red-emitting Li 4 Ca 2 B 8 O 16 : Eu3+ phosphor via the solid-state reaction. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the correspondence between local symmetry and luminescence properties were investigated in detail. Under the optimal 393 nm excitation, Li 4 Ca 2 B 8 O 16 : 0.33Eu3+ shows a strong red emission located at 612 nm ascribed to the 5D 0 →7F 2 transition of Eu3+. The calculated Judd-Ofelt parameters (Ω 2 and Ω 4) have clarified that Eu3+ has lower symmetry without an inversion center, resulting in the high value of R/O (the emission intensity ratio of 5D 0 →7F 2 to 5D 0 →7F 1) of 7.95 at x = 0.33 mol. The Li 4 Ca 2 B 8 O 16 : 0.33Eu3+ phosphor exhibits a high color purity of 94.99% with the chromaticity coordinates of (0.6547, 0.3449), perfect internal quantum efficiency (99.75%) and excellent thermal stability at high temperature (90.91% at 150 °C). The results indicate that this new Li 4 Ca 2 B 8 O 16 : Eu3+ phosphor can be used as the potential red component for pc-WLEDs. [Display omitted] • A series of new red-emitting Eu3+ doped Li 4 Ca 2 B 8 O 16 phosphors have been synthesized. • The incorporation of more Eu3+ ions leads to lower structural coordinated symmetry and higher color purity. • The Li 4 Ca 2 B 8 O 16 :0.33Eu3+ owns a high color purity of 94.99% and CIE of (0.6547, 0.3449). • Compared with the emission intensity at 25 °C, the overall emission intensity still remains 90.91% at 150 °C. [ABSTRACT FROM AUTHOR]

In order to investigated the new single-component white light emitting phosphate, Tm3+/Dy3+ doped KBaIn 2 (PO 4) 3 (KBIP) were successfully synthesized by solid state reaction. The structures of the compounds were investigated by XRD technique and Rietveld refinement methods. The luminescence properties were acquired and carefully analyzed. Meanwhile, the energy transfer process of Dy3+ and Tm3+ co-doped KBIP were investigated in detail. The KBIP: 0.05Dy3+ phosphor can obtain the single neutral white with the chromaticity coordinate of (0.3218, 0.3307) and CCT value of 6018 K, while the emitting color of Dy3+ and Tm3+ co-doped KBIP could be adjusted from blue to near white. Furthermore, the overall integral intensity at 150 °C of 0.05 Tm3+ and 0.05Dy3+ co-doped KBIP is 80.5% of that at 25 °C. The results are indicate Dy3+/Tm3+ doped KBIP phosphors own potential application in future wLEDs. [Display omitted] • A series of Dy3+/Tm3+ doped KBaIn 2 (PO 4) 3 phosphors were synthesized successfully. • The KBIP: 0.05Dy3+ phosphor can obtain the single neutral white with CIE of (0.3218, 0.3307). • The emitting color of Dy3+ and Tm3+ co-doped KBIP phosphors can be adjusted from blue to near white. • Compared with the emission intensity at 25 °C, the overall emission intensity still remains 80.5% at 150 °C. [ABSTRACT FROM AUTHOR]

High thermal stability and quantum efficiency are the two very significant factors for phosphors when concerning all kinds of related applications. Therefore, it is still main research topics as long as referencing to the luminescence phosphors. It is well known that deep trap and large band gap are beneficial to excellent thermal stability. In this work, a series of Na 2 BaCa 1- x Sr x (PO 4) 2 :0.03Eu2+ phosphors have been prepared by traditional solid state reaction. When the Sr2+ content increases, the emission intensity exhibits a blue shift phenomenon with the highest peak around 448 nm caused by the varied centroid shift (ε c) and the crystal field splitting (ε cfs). The thermal stability of Na 2 BaCa 0.2 Sr 0.8 (PO 4) 2 :0.03Eu2+ phosphor still approaches to 100.3% of that room temperature at 150 °C, while the external and internal quantum efficiency are greatly enhanced from 19.92% to 62.53%. It is due to the effect of the cation disorder by introducing the high level of Sr ion, which create the deep trap and broaden the bandgap, resulting in the anti-thermal quenching behavior and enhanced quantum efficiency. Moreover, Rietveld refinements, microstructure, decay curves and thermoluminescence are also adopted to shed light on related mechanism of luminous performance. Furthermore, a pc-WLED device has been fabricated through Na 2 BaCa 0.2 Sr 0.8 (PO 4) 2 :0.03Eu2+ blue phosphor mixed with commercial yellow phosphor (SrSi 2 O 2 N 2 :Eu2+) and red phosphor (Sr 2 Si 5 N 8 :Eu2+), which performs a color temperature of 4721 K with a high color rendering index of Ra = 91.9. In view of zero thermal quenching and favorable quantum efficiency, this new phosphor is a prospect candidate for blue phosphors in WLED application. Further, the work provides a new method and reference for the great enhancement of thermal stability and quantum efficiency of luminescence materials. Based on the crystal structure of Na2BaCa(PO4)2:Eu2+ phosphors, the PL, thermal dependent spectra and application in WLED of Na2BaCa0.2Sr0.8(PO4)2:Eu2+ phosphors have been detected. [Display omitted] • A series of solid solution Na 2 BaCa x Sr 1 -x (PO 4) 2 (x = 0–1.0) have been synthesized. • The thermal stability of Na 2 BaCa 0.2 Sr 0.8 (PO 4) 2 :0.03Eu2+ is 100.3% of that room temperature at 150 °C. • The external quantum efficiency of Na 2 BaCa 0.2 Sr 0.8 (PO 4) 2 :0.03Eu2+ is improved from 19.92% to 40.78%. • The fabricated white WLED shows the CIE of (0.3532, 0.3561), the CCT of 4721 K and CRI of 91.9. [ABSTRACT FROM AUTHOR]

Abstract: The rigid-plastic finite element Deform-3D software was employed to describe the plastic deformation behavior of TiAl billet (Ti-46.5Al-2.5V-1.0Cr-0.3Ni alloy) during its axisymmetric extrusion through a conical die. Under various extrusion conditions, the present numerical analysis investigated the strain distribution, the damage factor distributions and the die load during the extrusion process. The relative influences of the die semi-angle and the extrusion ratio were examined. The results show that the extrusion force was enhanced from 1.54 × 106 N to 2.81 × 106 N with a certain slop coefficient (about 0.04) when die semi-angle increased in the range 40°≤α ≤ 70°. The uniform effective strain and the lower propensity for fracture could be obtained at the 60° die semi-angle. The 60° die semi-angle will be an appropriate choice for the extrusion of TiAl alloy. With the raising of extrusion ratio, the effective strain, extrusion load and the damage factor in billet would also be increased. [ABSTRACT FROM AUTHOR]

Ce3+ doped CaAlSiN 3 is a promising broadband orange phosphor that can be applied in white light-emitting diodes (wLEDs) solid state lighting for general illumination. However, its emission color and quantum efficiency are not good enough to achieve high color rendering properties and luminous efficacy of wLEDs. In this work, we proposed to realize the spectral tuning and property enhancement of CaAlSiN 3 :Ce3+ by bandgap engineering via the cationic substitution of Ca by Sr. The relationship between photoluminescence and local coordination structure as well as electronic structure were revealed. The substitution led to a blue-shift in emission maximum by 13 nm (from 595 to 582 nm) and a highest external quantum efficiency of 55% (enhanced by 10%). This broadband yellow phosphor enabled to produce wLEDs with a color rendering index of 83.3, luminous efficacy of 114.6 l m/W and a color temperature of 4604 K. With the substitution of Ca by Sr in broadband yellow phosphor CaAlSiN 3 :Ce3+, a blue-shift in the emission maximum (from 595 to 582 nm) was attained, while the quantum efficiency and thermal stability of the phosphor containing 40% Sr were increased by 10 and 7.2% due to the decreased crystal field splitting and increased bandgap of the host. Image 1 • The bandgap engineering was adopted to realize the spectral tuning of CaAlSiN 3 :Ce3+ via the substitution of Ca by Sr. • The relationship between local structure and luminescence properties in Sr x Ca 1-x AlSiN 3 :Ce3+ was comprehensively discussed. • With the substitution, a blue-shift in the emission maximum (from 595 to 582 nm) was attained. • The quantum efficiency and thermal stability of the sample containing 40% Sr were raised by 10 and 7.2%, respectively. • This broadband yellow phosphor enabled to produce wLEDs with a color rendering index of 83.3. [ABSTRACT FROM AUTHOR]

Highly biocompatible and efficiently luminescent whiskers of the hydroxyapatite (Ca10(PO4)6(OH)2, HAp) doped with various concentrations (0‐5 at.%) of europium were prepared by hydrothermal synthesis and the Eu‐doped Hap‐coating layers onto the surface of titanium substrate were fabricated by the electrophoretic deposition (EPD) process for fluorescent probe application. The maximum doping concentration of Eu accommodating into the host lattice of HAp was detected as ~1.5 at.% and all the hydrothermally synthesized Eu‐doped HAp whiskers were found to have high crystallinity and orientation growth along the c‐axis by X‐ray diffraction (XRD) identification. The valence of the doped Eu was identified as trivalent and divalent coexistence at a concentration percentage of Eu3+: Eu2+ = 78%: 22% by X‐ray photoelectron spectroscopy (XPS) spectra. The replacement site of the doped Eu ions in the crystal structure of HAp host was clarified by Rietveld refinement. The whisker morphology of the hydrothermally synthesized particle was demonstrated by field‐emission scanning electron microscopy (FE‐SEM) observation and their component elements were analyzed by energy dispersive X‐ray (EDX) mapping. The photoluminescence (PL) emissions of the Eu‐doped HAp whiskers and fabricated their coating layers were both revealed mainly at ~615 nm (5D0 → 7F2) and ~697 nm (5D0 → 7F4), which is a wavelength that easily transmitting through living system for biological imaging. The PL emission are falling in the region of reddish orange and belonging to color temperature below 1500 K. Decay time and internal and external quantum efficiencies (QEs) were also measured to reveal them depending on the doping concentration of Eu. The hydrothermally prepared Eu‐doped HAp whiskers would be aimed at biomedical application, due to their promising fluorescent function of probe for in vivo imaging in medical diagnose by utilizing the superior biocompatibility of the HAp host and highly efficient luminescent property of the Eu activator. [ABSTRACT FROM AUTHOR]