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In this paper, Ce 3+ -activated iso-structural solid solutions La 5.99 Ce 0.01 M 4 (SiO 4 ) 6 F 2 (M = Ca, Sr and Ba) compounds were prepared for the first time. The structure and luminescence properties of the samples were investigated to explore the difference of cation substitution. The phase analysis indicated that all XRD peaks of the samples were indexed by a hexagonal cell with the space group of P 6 3 /m, and the phosphors showed strong blue light emission with broad bands. With the isomorphous substitution of Ba → Sr → Ca, the average bond length between Ce 3+ and anions is decreased and the crystal field around Ce 3+ is strengthened, resulting in the red-shift (from 410 nm to 423 nm) of the emission wavelength for La 5.99 Ce 0.01 M 4 (SiO 4 ) 6 F 2 (M = Ca, Sr, Ba). [ABSTRACT FROM AUTHOR]

A series of novel KLaSr3−x(PO4)3F:xEu2+ phosphors were synthesized for the first time. The crystal structure, photoluminescence properties, concentration quenching, decay analysis, and the temperature dependent luminescence properties were investigated in detail. The unit cell parameters for KLaSr3(PO4)3F were estimated to be a = 9.8997 Å, c = 7.4075 Å, and V = 628.7 Å3. The photoluminescence excitation spectrum of KLaSr3(PO4)3F:Eu2+ shows a broad band from 225 nm to 450 nm with a maximum at about 320 nm. KLaSr3−x(PO4)3F:xEu2+ phosphors exhibit a wide emission band ranging from 425 to 550 nm. KLaSr3(PO4)3F:Eu2+ phosphors exhibit good thermal stability up to 423 K. KLaSr3(PO4)3F:Eu2+ was fabricated with commercial green (Ba,Sr)SiO4:Eu2+ and red CaAlSiN3:Eu2+ phosphors to obtain a white-light-emitting diode. All the results demonstrate that KLaSr3(PO4)3F:Eu2+ are promising blue phosphors for white-light ultraviolet light-emitting diode applications. [ABSTRACT FROM PUBLISHER]

In this paper, La 1.45 Ce 0.05 Ba 3.5 (SiO 4 ) 1.5 (PO4) 1.5 F compound with apatite structure was synthesized via solid state reaction method. The phosphor exhibits two strong excitation bands at 279 nm and 345 nm in near ultraviolet light region. When excited at 345 nm, the emission peaks of the phosphor give a red-shift from 406 nm to 418 nm compared with that of 279 nm excitation. Besides, the site occupation of Ce 3+ was proposed based on structure refinement, luminescence, fluorescence decay curves, as well as CIE diagram. All the results indicated that Ce 3+ can occupy sites of La 3+ with nine and seven coordination and a possible mechanism was proposed to explain the luminescence properties observed. [ABSTRACT FROM AUTHOR]

A series of blue-emitting La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ ( x = 0, 1, 2, and 3) phosphors with apatite structure were synthesized by a solid-state reaction. The crystal structure and the photoluminescence properties were investigated in detail. The crystallographic occupancy of Ce 3+ in La 2.90 Ce 0.10 Ba 7 (SiO 4 ) 3 (PO 4 ) 3 F 2 and La 5.90 Ce 0.10 Ba 4 (SiO 4 ) 6 F 2 were studied based on Rietveld refinements results and the crystal chemistry rules. La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ exhibited strong blue light emission in the range of 407–414 nm with high thermal stability upon excitation at 276 nm. Besides, the activation energy E of La 5.90 Ce 0.10 Ba 4 (SiO 4 ) 6 F 2 and La 2.90 Ce 0.10 Ba 7 (SiO 4 ) 3 (PO 4 ) 3 F 2 phosphors were calculated to be 0.152 and 0.177 eV. These results suggest that La 5.90− x Ba 4+ x (SiO 4 ) 6− x (PO 4 ) x F 2 :0.10Ce 3+ is a potential blue phosphor candidate for near-UV-pumped w -LEDs. [ABSTRACT FROM AUTHOR]

In this paper, a series of novel luminescent Sr 1− x Al 12 O 19 : x Eu 2+ phosphors were synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, as well as the decay curves were investigated. The quenching concentration of Eu 2+ in SrAl 12 O 19 was about 0.15 (mol). Upon excitation at 378 nm, the composition-optimized Sr 0.85 Al 12 O 19 :0.15Eu 2+ exhibited strong broad-band green emission at 530 nm with the CIE chromaticity (0.2917, 0.5736). The results indicate that Sr 1− x Al 12 O 19 : x Eu 2+ phosphors have potential applications as green-emitting phosphors for UV-pumped white-light LEDs. [ABSTRACT FROM AUTHOR]

Single-phase Ba 10− x − y (PO 4 ) 6 O: x Eu 2+ , y Mn 2+ samples with apatite structure have been synthesized via a solid-state reaction method. The phase structure, luminescence properties, lifetime, PL thermal stability, as well as fluorescence decay curves of the samples were investigated. Effective energy transfer occurs from Eu 2+ to Mn 2+ in Ba 10 (PO 4 ) 6 O and a possible mechanism of the energy-transfer from Eu 2+ to Mn 2+ is proposed. The critical distances R c was calculated by concentration quenching and turned out to be about 0.817 nm ( x c =0.21). The CIE and thermally stable luminescence behaviors of Ba 9.94 (PO 4 ) 6 O:0.06Eu 2+ phosphor were also studied in detail. All the results indicate that Ba 10− x − y (PO 4 ) 6 O: x Eu 2+ , y Mn 2+ phosphors have potential applications as near UV-convertible phosphors for white light-emitting diodes. [ABSTRACT FROM AUTHOR]

A series of novel luminescent phosphors Sr 10 (PO 4 ) 6 O:Eu 2+ with apatite structure were synthesized via a high temperature solid-state reaction. The phase structure, photoluminescence (PL) properties, the PL thermal stability, as well as the fluorescence decay curves of the samples were investigated to characterize the resulting samples, and the selected Sr 9.97 (PO 4 ) 6 O:0.03Eu 2+ phosphor exhibits strong thermal quenching resistance, retaining the luminance of 88.73% at 150 °C. The quenching concentration of Eu 2+ in Sr 10 (PO 4 ) 6 O was about 0.03 attributing to the dipole–quadrupole interaction. The Sr 10 (PO 4 ) 6 O:Eu 2+ phosphor exhibited a broad-band blue emission at 439 nm upon excitation at 346 nm. The results indicate that Sr 10 (PO 4 ) 6 O:Eu 2+ phosphors have potential applications as near UV-convertible phosphors for white-light UV LEDs. [ABSTRACT FROM AUTHOR]

A series of new luminescent emission-tunable phosphors Sr 2 La 8 (SiO 4 ) 6 O 2 :Ce 3+ , Tb 3+ with apatite structure have been synthesized by a high temperature solid-state reaction. The phase structure, photoluminescence emission and excitation spectra, lifetime, as well as the effect of Tb 3+ concentration are investigated to characterize the resulting samples. The critical distance was calculated to be 8.26 Å by using the concentration quenching method. The intense green emission was observed in the Sr 2 La 8 (SiO 4 ) 6 O 2 :Ce 3+ , Tb 3+ phosphors on the basis of the efficient energy transfer from Ce 3+ to Tb 3+ with an efficiency of 68.55%. And a possible mechanism of the energy-transfer from Ce 3+ to Tb 3+ ion is also proposed. The results indicate that Sr 2 La 8 (SiO 4 ) 6 O 2 :Ce 3+ , Tb 3+ phosphors have potential applications to be used as near UV-convertible phosphors for white light-emitting diodes because of the broad excitation in the near-ultraviolet range and the efficient green emission light. [ABSTRACT FROM AUTHOR]

Abstract: We report a series of color-tunable Sr3.45Y6.5O2(PO4)1.5(SiO4)4.5:Eu2+,Mn2+ (SYPSO:Eu2+,Mn2+) phosphors in this work. The photoluminescence excitation and emission spectra, lifetime, and concentration-dependent effect were investigated, respectively. The energy transfer (ET) mechanism was verified as the dipole–dipole interaction, and the ET efficiency as well as the critical distance is also estimated. The emission colors of the obtained phosphors can be tuned from green to yellow by controlling the doping content of the Mn2+ ions with the fixed Eu2+ content. These results indicate that SYPSO:Eu2+,Mn2+ can be acted as a good candidate for the application in white light-emitting diodes. [Copyright &y& Elsevier]

Single-phase Ba10-x-y (PO4)6O:xEu2+,yMn2+ phosphors are prepared by solid state reaction of stoichiometric mixtures of BaCO3, NH4H2PO4, Eu2O3, and MnCO3 (alumina crucibles, flowing 10% H2/90% N2, 1200 °C, 5 h). [ABSTRACT FROM AUTHOR]

Sr10(PO4)6O:Eu2+x (x = 0.005-0.07) is prepared by solid state reaction of stoichiometric amounts of SrCO3, (NH4)2HPO4, and Eu2O3 in a reducing atmosphere of 5% H2/N2 (alumina crucible, 1300 °C). [ABSTRACT FROM AUTHOR]

The title phosphors are prepared by solid state reactions of SrCO3, SiO2, CeO2, La2O3, and Tb4O7 (alumina crucible, flowing 5%H2/95%N2, 1350 °C, 5 h). [ABSTRACT FROM AUTHOR]

The Ca 9 La(PO 4 ) 5 (SiO 4 )Cl 2 :Dy 3+ (CLPSCl:Dy 3+ ) powder phosphor with apatite structure has been successfully synthesized via high-temperature solid state method. Single phase in such phosphor was verified through X-ray diffraction (XRD) technique. The Dy ions concentration dependent luminescence properties including emission, excitation and lifetimes of Dy ions were characterized using photoluminescence (PL) spectroscopy. The results showed that CLPSCl:Dy 3+ phosphor could efficiently assimilate the n -UV light and emit blue (~486 nm) and yellow light (~578 nm), originating from the f-f transitions of Dy 3+ . The critical Dy 3+ quenching concentration (QC) was determined to be about 12 mol%. The concentration quenching mechanism was also determined to be dipole–dipole interaction. [ABSTRACT FROM AUTHOR]

Tb 3+ -Sm 3+ co-doped Sr 9 Gd(PO 4 ) 5 (SiO 4 )F 2 (SGPSF) phosphors were prepared through a solid-state reaction, and their luminescence properties as well as energy transfer mechanism have been investigated in detail. The SGPSF:Tb 3+ , Sm 3+ phosphors system could be efficiently excited at wavelengths ranging from 200 to 500 nm, which is well matched with the spectra of near ultraviolet chips. The emission of SGPSF:Tb 3+ , Sm 3+ phosphor covers the entire visible region with sharp peaks in the blue, green, and red regions. The emission color of SGPSF:Tb 3+ , Sm 3+ could be adjusted from green (0.275, 0.378) to red (0.519, 0.295) by controlling the doping content of Sm 3+ /Tb 3+ . [ABSTRACT FROM AUTHOR]

An anti-defect engineering strategy, inspired by photocatalytic and photovoltaic materials, was proposed to develop high-efficiency phosphors in whitlockite families. Significant enhancement of photoluminescence intensity (2.46 times), thermal stability (87.92% at 150 °C), cathodoluminescence intensity (3.34 times), quantum efficiency (IQE sharply up to nearly 100%) were simultaneously realized by constructing a rigid structure and removing vacancy defects. The developed phosphors exhibited promising applications in the fields of warm-white LEDs, plant growth lighting and information security. [Display omitted] • Anti-defect engineering strategy is proposed to develop high-efficiency phosphors. • The internal quantum yield is sharply improved from 38.90% to 99.07%. • The mechanism of improvement is revealed by defect-related characterizations. • DFT calculation shows the positive role of Debye temperature and alkali metal ions. • Promising applications in warm-white LEDs / plant-growth lighting are demonstrated. Lacking an effective strategy to simultaneously address the challenges of quantum efficiency, luminescence intensity and thermal stability has become the key bottleneck for further development and large-scale application of solid-state lighting technology. Herein, inspired by the defect-engineering used in photoelectrocatalytic and photovoltaic materials, we acted in a diametrically opposite way and unprecedentedly proposed an anti-defect engineering strategy to develop high-efficiency phosphors. By constructing a rigid structure and introducing alkali metals M to remove cation vacancy defects, similar to building blocks and jigsaw puzzle, we developed three groups of whitlockite phosphors, namely Ca 3- x Sr x (PO 4) 2 :Ce3+, Ca 3 (PO 4) 2 :Ce3+, M and (Ca 0.5 Sr 0.5) 3 (PO 4) 2 :Ce3+,Na+,Mn2+, and synchronously realized the significant enhancement of photoluminescence intensity (2.46 times), thermal stability (87.92% at 150 °C), cathodoluminescence intensity (3.34 times), quantum yield (from 38.90% to 99.07%). We characterized the defect concentration by positron annihilation technique (PAT), and calculated Debye temperature (ΘD) and simulated the occupation of M according to DFT theory to reveal the improvement mechanism. Some advanced applications were also explored in this work, including warm-white LEDs, plant growth lighting and information security. The anti-defect engineering proposed in this work may contribute to the further development of high-efficiency phosphors for the next-generation smart solid-state lighting technologies. [ABSTRACT FROM AUTHOR]

Novel reddish Mg 3 Gd 2 Ge 3 O 12 : RE3+ (RE = Sm, Eu) phosphors with high thermal stability have been designed and developed. In this work, Mg 3 Gd 2 Ge 3 O 12 was first synthesized for being used as the phosphor host. The X-ray diffraction and Rietveld refinement testified that the MGGO: Sm3+ and MGGO: Eu3+ crystallized in a cubic unit cell with space group I a-3d (230). The photoluminescence properties were studied in detail, MGGO: Sm3+ and MGGO: Eu3+ can be obviously excited at 403 and 395 nm, which could guarantee efficient absorption through commercial n -UV chip. Benefiting from the inverse garnet highly rigid framework, MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors had a favorable thermal resistance due to large activation energies (MGGO: 0.04Sm3+: 0.291 eV, MGGO: 0.9Eu3+: 0.238 eV). The emission intensity of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ can still preserve about 97.85% and 91.58% at working temperature (423 K) compared to the initial intensity (298 K). All results indicated Mg 3 Gd 2 Ge 3 O 12 : RE3+ (RE = Sm, Eu) phosphors have potential usage for full-spectrum w-LED applications as red component. • Crystal structure of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors are investigated in detail. • MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ phosphors have a favorable thermal resistance due to large activation energies. • MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ can be obviously excited at 403 and 395 nm. • CIE chromaticity coordinates of MGGO: 0.04Sm3+ and MGGO: 0.9Eu3+ are (0.5153, 0.4709) and (0.4937, 0.3765). [ABSTRACT FROM AUTHOR]