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Abstract: Orange emitting Sr2.96−x Ba x SiO5: Eu2+ phosphors have been synthesized by a method using Sr2SiO4 instead of simple oxides and carbonate as precursor. The photoluminescence properties, radiative lifetime and formation process were investigated by PL spectra, lifetime decay and XRD analysis, respectively. X-ray diffraction analysis indicates that the phosphor has a single phase of Sr3SiO5 without residual Sr2SiO4 and BaSi4O9 phases. Under 460nm excitation, the emission band of Sr2.96−x Ba x SiO5: Eu2+ has a red-shift from 580–598nm due to varied Ba2+ concentration. Particularly, the emission intensity of Sr2.56Ba0.4SiO5: 0.02Eu2+ sample increased significantly in comparison with the commercial SSE phosphor. The radiative lifetime τ 0 are estimated to be 1.999, 2.316, 2.716 and 2.932μs for samples of x=0, 0.2, 0.4 and 0.6, respectively. It indicates that Eu2+ ions are in different surroundings and the Sr2+ sites were substituted by Ba2+ completely. Compare with the conventional solid-state reaction method, the Sr2.96−x Ba x SiO5: Eu2+ phosphors synthesized by this method show higher crystallinity and more efficient orange emission. [Copyright &y& Elsevier]

Abstract: A green-emitting phosphor, Eu2+-activated Ba3Si6O9N4 phosphor, was synthesized by a conventional solid state reaction method. X-ray diffraction patterns showed that the synthesized phosphor sintered at 1300°C for 6h was a Ba3Si6O9N4 pure phase. It could be efficiently excited by UV–blue light (280–500nm) and showed a single intense broad emission band (470–625nm). Suitable excitation range makes it match well with the emission of near-UV or blue LEDs. Concentration quenching of the doped-Eu2+ ions occurred at x=0.15, and the critical distance is calculated to be about 1.807nm by theory of energy transfer. The result indicates that Ba3Si6O9N4:Eu2+ is a promising green-emitting phosphor for white LEDs. [Copyright &y& Elsevier]

An emission-tunable, Eu2+-activated, Ba2Ca(PO4)2:Eu2+ phosphor was synthesized by a conventional solid-state reaction. X-ray powder diffraction (XRD) and FT-IR spectroscopic analysis confirmed the phase formation. Electron paramagnetic resonance (EPR) analysis indicated there are three different crystallographic Ba2+ sites, namely, Ba(1), Ba(2) and Ba(3), occupied by the Eu2+ ions. The excitation and emission spectra, concentration dependence of the emission intensity and decay curves of the phosphor were investigated. The results showed that with increasing Eu2+ concentration, the emission peak wavelength redshifted from 457 to 500 nm, and the color hue can be tuned from a greenish blue to a yellowish green. A white LED was fabricated using a near ultraviolet (n-UV) 410 nm chip pumped with a blend of phosphors consisting of greenish blue-emitting Ba1.97Ca(PO4)2:0.03Eu2+ and red-emitting Ca3.97(PO4)2O:0.07Eu2+. When the applied current was 350 mA, the white LED had Commission International de l'Eclairage color coordinates of (0.3249, 0.3421) at a white light (correlated color temperature = 6020 K) and an excellent color rendering index of 93. [ABSTRACT FROM AUTHOR]

Abstract: Ba3Si6O9N4 phosphors co-doped with Ce3+ and Eu2+ were synthesized via the solid-state reaction method. The samples could display varied color emission from blue and ultimately to green under the excitation of ultraviolet (UV) light or blue light with the appropriate adjustment of the relative proportion of Ce3+/Eu2+. The luminescence intensity of Ba3Si6O9N4:Eu2+ can be efficiently enhanced by codoping with Ce3+. The energy transfer mechanism from Ce3+ to Eu2+ in Ba3Si6O9N4:Ce3+, Eu2+ is electric dipole–dipole interaction, and the critical distance is calculated to be about 24.86Å by the spectra overlap method. [Copyright &y& Elsevier]

Abstract: A novel phosphor Ba3Si6O9N4 doped with Eu and M (M=Ce3+, Mn2+ and Dy3+) has been synthesized by a solid state reaction at 1350°C for 6h under 90%N2/10%H2 atmosphere. It could be efficiently excited by UV–blue light (280–500nm) and showed a single intense broadband emission (470–625nm). Suitable excitation range make it match well with the emission of near-UV LEDs or blue LEDs. It was found that the luminescence intensity of the Ba3Si6O9N4:Eu2+ phosphors can be efficiently enhanced by codoping with M. The addition of M in Ba3Si6O9N4:Eu2+ remarkably enhances the luminescent intensity by the factor of 198%, 166% and 188% for Ce3+, Mn2+ and Dy3+, respectively. The Ba3Si6O9N4:Eu2+ phosphor has potential application as a phosphor for white light-emitting diodes. [Copyright &y& Elsevier]

Abstract: A novel Ce3+/Eu2+ co-activated LiSr4(BO3)3 phosphor has been synthesized by traditional solid-state reaction. The samples could display varied color emission from blue towards white and ultimately to yellow under the excitation of ultraviolet (UV) light with the appropriate adjustment of the relative proportion of Ce3+/Eu2+. The resonance-type energy transfer mechanism from Ce3+ to Eu2+ in LiSr4(BO3)3:Ce3+, Eu2+ phosphors is dominant by electric dipole–dipole interaction, and the critical distance is calculated to be about 29.14Å by the spectra overlap method. White light was observed from LiSr4(BO3)3:mCe3+, nEu2+ phosphors with chromaticity coordinates (0.34, 0.30) upon 350nm excitation. The LiSr4(BO3)3:Ce3+, Eu2+ phosphor has potential applications as an UV radiation-converting phosphor for white light-emitting diodes. [Copyright &y& Elsevier]

Abstract: A novel Eu2+ activated 60SiO2–40BaO (mol%) glass ceramics phosphor was prepared and the optical properties were investigated. X-ray diffraction (XRD) and Raman spectra confirmed the formation of Ba2Si3O8 nano-crystals in the glass matrix. The Eu2+ activated glass ceramics exhibited broad emission band centered at 518nm due to the 4f65d1→4f7 transition of Eu2+. Compared with the glass, the emission intensity of Eu2+ activated glass ceramics was much stronger, and the peak wavelength shifted toward shorter wavelength. The photoluminescence excitation (PLE) spectra of the glass ceramics showed an overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). According to the photoluminescence (PL) spectra, the CIE chromaticity coordinates of the Eu2+ activated glass and glass ceramics were calculated. The results indicated that the Eu2+ activated glass ceramics containing Ba2Si3O8 nano-crystals can be used as a potential green emitting phosphor under UV-LED excitation. [Copyright &y& Elsevier]

Abstract: In the present work, transparent Eu2+/Dy3+ co-doped white light-emitting glass ceramics containing CaF2 were successfully prepared under reducing atmosphere. Their luminescence properties have been studied by excitation and emission spectra. A combination of blue, yellow and red emissions has emerged in Eu2+/Dy3+ co-doped glass and glass ceramics, which allows the observation of bright white light when the samples are excited by the ultraviolet light. Energy transfer (ET) from Eu2+ to Dy3+ is discovered by directly observing the luminescence intensity of Dy3+ in the Eu2+/Dy3+ co-doped glass which is much stronger than that in the Dy3+-doped glass. ET from Eu2+ to Dy3+ in glass is further confirmed by fluorescence studies performed on the samples with various activator (Dy3+) concentrations. The color of luminescence could be adjusted by varying the proportions of europium and dysprosium. The optimal composition generates white light with chromaticity coordinates (0.296, 0.311). The results indicate that Eu2+/Dy3+ co-doped glass ceramics containing CaF2 nano-crystals is a potential material for white LED. [Copyright &y& Elsevier]

High-efficiency phosphor with excellent luminescence properties and thermal stabilities is essential for phosphor-converted white light-emitting diodes (w-LEDs). Compared with red and green phosphors, near-ultraviolet excited blue phosphors with high efficiency and excellent thermal stability are still scarce, and the development of efficient blue phosphors remains challenging. NaLi 3 SiO 4 : Eu2+ (NLSO: Eu2+) is a promising narrow-band blue phosphor. In this paper, a series of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ (0.05 ≤ y ≤ 0.2) phosphors were successfully synthesized by high-temperature solid-state reaction through co-doping a small amount of K+ ions in the matrix, significantly improving their luminescence property and thermal stability. Because of the weaker electronegativity of K+ ions, the emission peaks of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ were slightly blue-shifted from 467 to 463 nm compared with those of NLSO: Eu2+. With an increase in the number of K+ ions, the luminescence intensity of the phosphors increased. When the content of the K+ ion reached 0.2, the luminescence intensity of the Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ (NKLSO: 5%Eu2+) phosphor reached its maximum. Compared to the NLSO: 5%Eu2+ phosphor, the luminescence intensity increased by approximately 300 %. At 150 °C, the luminescence intensity of NLSO: 5%Eu2+ phosphor was retained at 75.98 % compared with room temperature, while the NKLSO: 5%Eu2+ phosphor maintained a luminescence intensity of 84.36 % relative to room temperature, demonstrating excellent thermal stability. The enhanced luminescence performance of the NKLSO: Eu2+ phosphor makes it a promising high-efficiency blue phosphor for phosphor-converted w-LEDs. Through co-doping a small amount of K+ ions into the NaLi 3 SiO 4 : Eu2+, significantly improving the luminescence property and thermal stability. [Display omitted] • A series of Na 1-y K y Li 3 SiO 4 : 5%Eu2+ (0.05 ≤ y ≤ 0.2) phosphors were successfully synthesized through co-doping K+ ions in the matrix. The weaker electronegativity of K+ ions makes it easier for Eu3+ to be reduced to Eu2+. • In luminescence properties, when the content of the K+ ion reached 0.2, the luminescence intensity of the Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ phosphor reached its maximum. Compared to the NaLi 3 SiO 4 : 5%Eu2+ phosphor, the luminescence intensity increased by approximately 300 %. • The Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ exhibited superior thermal stability compared to NaLi 3 SiO 4 : 5%Eu2+. The luminescent intensity of NaLi 3 SiO 4 : 5%Eu2+ at 150 °C remains 75.98 % of the room temperature intensity, while the luminescent intensity of Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ is significantly increased to 84.36 %. • The narrowband blue phosphor Na 0.8 K 0.2 Li 3 SiO 4 : 5%Eu2+ is a potential candidate for n-UV excited w-LEDs applications because of its excellent luminescence properties. [ABSTRACT FROM AUTHOR]

Full-spectrum white LED (w-LED) lighting is primarily achieved through the combination of multiple-color phosphors excited by the chip, and making the development of efficient multi-color phosphors based on single matrix is an excellent choice for full-spectrum w-LED. In this paper, a series of Rb 2 KNa(Li 3 SiO 4) 4 : xEu2+ (0.1 % ≤ x ≤ 15 %) phosphors were successfully synthesized via high-temperature solid-state reaction with varied Eu2+ concentration. At low doping concentration, the Eu2+ ions exhibit primarily green emission at 530 nm in the phosphor. However, as the doping concentration of Eu2+ ions increase, the emission spectrum undergoes a significant transformation. A cyan emission occurs at 478 nm, resulting in the spectral conversion from a green single-peak emission to a dual-peak emission of cyan and green. The spectral conversion is attributed to the changes in the positioning of Eu2+ ions within the crystal lattice. The obtained phosphors demonstrate excellent thermal stability and can be utilized in w-LED devices. After encapsulation with a blue LED chip, it achieves a color rendering index of 91.8 and a correlated color temperature of 4085 K, showcasing its significant application value in the field of full-spectrum w-LED. • By adjusting the doping concentration of Eu2+ ions and occupied lattice position, the emission spectrum of the Rb 2 KNa(Li 3 SiO 4) 4 : xEu2+ (0.1 % ≤ x ≤ 15 %) phosphor was regulated from a single-peak emission of 530 nm (green) to a dual-peak emission of 478 nm (cyan) and 530 nm (green) . • The phosphors demonstrated excellent thermal stability. Compared with room temperature, the emission intensities of 478 nm and 530 nm of Rb 2 KNa(Li 3 SiO 4) 4 : 0.08Eu2+ phosphor at 150 °C maintained 84.48 % and 83.71 % , respectively. • Rb 2 KNa(Li 3 SiO 4) 4 : Eu2+ proves to be a promising narrow-band cyan-green phosphor with excellent luminescent performance, making it suitable for application in w-LED . [ABSTRACT FROM AUTHOR]

Abstract We investigated thermal and fluorescence properties of Er3+ doped fluoroaluminate multi-component glasses modified by TeO 2 and CaCl 2. A better thermal stability with a higher Δ T (98 °C) was obtained for the TeO 2 modified sample, which had a high radiative transition probability (A rad) of the Er3+: 4I 11/2 →4I 13/2 transition. In addition, under 980 or 808 nm excitation, the Er3+ 2.7 µm emission intensity of the TeO 2 modified sample decreased owing to its increased hydroxyl content induced by TeO 2 modifiers. Excellent mid-infrared fluorescence along with a longer lifetime (3.48 ms) were observed in the glass tuned by CaCl 2. The CaCl 2 modified sample exhibited higher stimulated absorption and emission cross sections, obtained using the Füchtbauer-Ladenburg and McCumber formulas. Moreover, the strong effect of hydroxyl on the mid-infrared fluorescence properties was systematically analyzed. The oxygen network modifiers in the fluoroaluminate multi-component glass provide improved thermal properties, while the AlF 3 -based glasses with chlorine network modifiers have larger potentials for applications in the mid-infrared region. [ABSTRACT FROM AUTHOR]

Phosphor-in-glass (PiG) to generate white light outputs under excitement in laser diodes (LDs) has set off a research wave owing to its flexible and adjustable luminescence, but the unavoidable loss between two different materials (phosphor and glass) has limited possible improvements in quantum efficiency (QE) and luminous efficiency (LE). In this paper, an optimized phosphate glass is creatively designed, the low sintering temperature and high optical transmittance reduce unnecessary optical losses and ensures the LE. After being compounded with the matrix glass, the Y 3 Al 5 O 12 : Ce3+ (YAG: Ce3+) phosphor not only maintains the integrity of the particles but also shows excellent luminous performance with a high QE of 89.51%. Under the excitation of 450 nm blue LD, a maximum LE of 307 lm/W is reached, indicating that the designed material has an outstanding laser fluorescence conversion ability and broad application prospects in the fields of laser lighting and displays. • A new phosphate glass customized for high efficiency PiG through component regulation. • The introduction of ZnCl 2 ensures the low T g and high transmittance of phosphate glass. • The completed YAG phosphor particles maintain high quantum efficiency in PiG. • Outstanding laser lighting capability is demonstrated with the luminous efficiency of 307 lm/W. [ABSTRACT FROM AUTHOR]

In pursuit of healthy lighting, the exploitation of high-quality Eu2+-activated phosphors available for near-ultraviolet light-emitting diode (NUV-LED) chip-based white LED (WLED) has fetched growing interest. Herein, a novel NUV-light excitable Rb 3 GdSi 2 O 7 : Eu2+ phosphor is successfully synthesized via a high-temperature solid-state reaction method. The crystal structure of Rb 3 GdSi 2 O 7 is found to be hexagonal, belonging to space group P6 3 /mmc. The Rb 3 GdSi 2 O 7 : Eu2+ phosphor exhibits a broad excitation band in the 300–450 nm wavelength range, and it emits strong yellow-green light with peak at 543 nm upon 365 nm excitation. Benefitting from the high structure rigidity of host matrix, Rb 3 GdSi 2 O 7 : Eu2+ also possesses a desired luminescence thermal stability (423 K, 85.6%). The WLED device fabricated using a 365 nm chip and a blend of the as-prepared Rb 3 GdSi 2 O 7 : Eu2+ yellow-green phosphor and commercial BaMgAl 10 O 17 : Eu2+ blue phosphor displays an excellent color-rendering index of 95.9 at a low correlated color temperature of 4373 K. This work confirms the applicative potential of Rb 3 GdSi 2 O 7 : Eu2+ in NUV-converted warm WLEDs, which may promote the development of high-color-quality healthy lighting. [Display omitted] • Eu2+ emission band in Rb 3 GdSi 2 O 7 is located at 543 nm upon 365 nm excitation. • Rb 3 GdSi 2 O 7 : Eu2+ shows high thermal stability (423 K, 85.6%) due to the rigid host lattice. • The WLED fabricated by Rb 3 GdSi 2 O 7 : Eu2+ has high CRI (95.9) and low CCT (4373 K). [ABSTRACT FROM AUTHOR]

Abstract It was reported that the UC emission intensity can be improved by introducing a thermal field and this phenomenon is highly related to the Yb3+ ions. Herein, we verify the thermal-induced UC enhancement degree can be further increased by separating the Yb3+ ions in the core and shell to promote the population of the defect energy level and inhibit the back energy transfer from Ho3+ to Yb3+ ions. Graphical abstract Image 1 Highlights • Thermal-induced enhancement degree of Ho3+ decreases with increasing Ho3+ doping content. • High Yb3+ content benefit the population of the defect energy level. • High Yb3+ content also induce back energy transfer from Ho3+ to Yb3+ions. • The enhancement degree is further increased by constructing core-shell structure. [ABSTRACT FROM AUTHOR]

Highly rare earth（RE）ions doped glass laser materials can produce efficient single frequency mid-infrared laser. In this work, a series germanosilicate glasses with various high erbium-doping concentration (up to 4 mol%) and without concentration quenching are fabricated. Spectroscopic properties and energy transfer (ET) mechanism of efficient Er 3+ : 4 I 11/2 → 4 I 13/2 transition have been investigated in detail upon a conventional 980 nm Laser Diode. The dense structure of silicate glass can be dissolved effectively by the introduction of GeO 2, which was analyzed by Raman spectra, so that the compatibility and luminous intensity of RE ions were improved. The high predicted spontaneous transition probability (A rad = 37.65 s −1 ) based on the Judd-Ofelt theory and large calculated emission cross section (8.8 × 10 −21 cm 2 ) are obtained. The above results indicate that these glasses are promising to be the single frequency mid-infrared laser material. [ABSTRACT FROM AUTHOR]

We report a detailed spectroscopic investigation of a series of fluorotellurite glasses with different Er 3+ ions concentration in system 50TeO 2 -27BaF 2 -9ZnF 2 -8YF 3 -3MgF 2 -3NaF-xErF 3 -1HoF 3 (x = 1,2,3 mol%). Intense 2 μm emission and 2.75 μm emission with high absorption and emission cross-section were observed under 980 nm LD pumping, and the maximum gain coefficient around 2750 nm was as high as 2.41 cm −1 , suggesting the prepared glasses are a competitive candidate for mid-infrared laser materials. Besides, it was found that the trend of 2 μm and 2.75 μm emission intensity varied with Er 3+ ions concentration was different. Energy transfer process was discussed subsequently to explain this phenomenon. Furthermore, we quantitatively investigate the energy transfer efficiency from Er 3+ : 4 I 13/2 level to Ho 3+ : 5 I 7 level. [ABSTRACT FROM AUTHOR]

A series of β-Sr 1.98- y Mg y SiO 4-1.5 x N x : 0.02Eu 2+ ( x = 0, 0.3, 0.6, 0.9, 1.2 and 4/3, 0 ≤ y ≤ 0.5, β-S(M)SON: Eu 2+ ) phosphors were synthesized by a conventional solid state reaction method. The coordination environments of Eu 2+ are modified effectively via the introduction of N 3- and Mg 2+ using different concentration, which is confirmed by XRD refinement results and PL spectra. Both fourier transform infrared (FT-IR) spectra and energy dispersive spectroscopy (EDS) analysis qualitatively confirm that the existence of N 3- . The crystal structures of β-Sr 2 SiO 4-1.5 x N x (β-SSON): Eu 2+ and β-Sr 2- y Mg y Si(O,N) 4 : Eu 2+ (β-SMSON, x = 4/3, y = 0.1) have been determined effectively. Rietveld refinement indicates that N 3- dopants most likely partly substitute O 2 2− site. With the increase of N content, the unit cell volume and partial Si O and Sr N bond lengths gradually decrease, which are coincided each other. With the introduction of N 3- , the emission of Eu(I) (∼465 nm) hardly change but that of Eu(II) (∼540 nm) splits into two emission bands as Eu(II) (∼540 nm) and Eu(II) ′ (∼616 nm). According to the analysis of XRD data, unit cell volume, FT-IR spectra, photoluminescence (PL) and reflectance spectra of β-SMSON: Eu 2+ , it can be concluded that the incorporation of Mg 2+ into the host leads to interstitial sites rather than substitutional ones. Mg 2+ doping couldn't change the dominant peak wavelengths (DPWs) of Eu(I), Eu(II) and Eu(II) ′ sites but only affects the PL intensity of title phosphors and could offset the nitridation effects. The concentration quenching mechanism and thermal activation energy of β-SSON: Eu 2+ phosphors are determined effectively. The β-S(M)SON: 0.02Eu 2+ phosphor have the feature that it can achieve color-tunable white light-emitting combined with blue light emitting diodes (LEDs) with single activator doped and single-phase host, which enables these materials to be enormous possibilities used in white light emitting diodes. [ABSTRACT FROM AUTHOR]

A novel tunable red to yellow emitting phosphor, (Ca, Ba) 4 (PO 4 ) 2 O:Eu 2+ is reported that displays a broad emission from 500 to 800 nm, and its emitting color can be adjusted from red to yellow by changing Ba 2+ doping concentration. X-ray powder diffraction (XRD) analysis confirmed the phase formation. Excitation and emission spectra, and concentration dependence of emission intensity of the phosphor were investigated. The results showed that the emission peak wavelength take blue-shifted from 640 to 545 nm and the color hue can be tuned from red to yellow with increasing Ba 2+ concentration. When single-phase (Ca 3.85 Ba 0.10 )(PO 4 ) 2 O:0.05Eu 2+ phosphor is pumped by a blue InGaN light-emitting diode, we obtain white light with color rending index ( R a ) between 84.0 and 90.6 and color temperatures between 4000 and 5500 K, which suggests that this material is competitive as a color conversion material for solid state lighting. [ABSTRACT FROM AUTHOR]

Quantum dot (QD)-embedded glass, which is a high-performance multifunctional optical material, has the combined advantages of excellent optical properties of QDs and easy processing of glass. In this study, an inorganic PbS QD embedded multicomponent glass, which produces variable emission at different ultraviolet (UV) excitation wavelengths, is synthesized. The samples are fabricated via a facile melt-quenching method and their structural, optical, photoluminescent, and morphological properties are discussed. The QD glass exhibits broad-band UV excitation in the range of 250–400 nm, and the full width at half maximum of the emission peaks of the QD glasses reaches 177.8 and 158.5 nm at room temperature under an excitation of 365 and 310 nm, respectively. Notably, white light emission with a high color rendering index is obtained under UV excitation at 350 and 365 nm by doping blue light emitting rare earth (RE) Tm3+ ions into the system. The doped samples exhibit excellent color stability and their CIE coordinates shift along the Planck blackbody locus with increasing temperature. Further, based on the differences in the luminescence mechanisms of the PbS QDs and Tm3+ ions, the application potential of the RE-doped PbS QD-embedded glasses in optical thermometry is discussed. The results demonstrate the application potential of these optically multifunctional inorganic QD glasses in the fields of optical conversion, anti-counterfeiting, white light illumination, and non-contact optical temperature measurement. [Display omitted] • PbS QDs were successfully prepared in an inorganic glass with broad-band emission. • Variable emission of PbS QDs glass at different UV excitation were obtained. • High CRI white light was obtained by combining the emission of PbS QDs with Tm ions. • A novel optical thermometer based on the inorganic PbS QDs glasses was revealed. [ABSTRACT FROM AUTHOR]

A series of single-phase white-light-emitting phosphors, Eu 2+ -activated Ba 3 GdNa(PO 4 ) 3 F phosphors were synthesized by solid-state reactions. The crystal structure of Ba 3 GdNa(PO 4 ) 3 F was been identified by Rietveld refinement of X-ray diffraction pattern. The Eu 2+ -activated Ba 3 GdNa(PO 4 ) 3 F phosphors exhibit broad excitation spectra from 250 to 420 nm, which matched well with the n-UV LED chips. Under the excitation of 365 nm, the emission spectrum almost covered the entire visible region including two emission bands peaked at 472 nm and 640 nm. Three different Eu 2+ emission centers in Ba 3 GdNa(PO 4 ) 3 F:Eu 2+ phosphor were confirmed by their fluorescence decay lifetimes. The optimal concentration of Eu 2+ in Ba 3 GdNa(PO 4 ) 3 F: x Eu 2+ was 3 mol% and the corresponding concentration quenching mechanism was verified to be exchange coupling interaction. Furthermore, the white light-emitting diode fabricated with Ba 3 GdNa(PO 4 ) 3 F:0.05Eu 2+ phosphor and a 370 nm UV chip has a CIE of (0.3267, 0.2976) with a color-rendering index of 78.4 at the CCT of 5287 K. [ABSTRACT FROM AUTHOR]

Ho3+ ion has attracted attention owing to its rich energy level structures and ability to emit emissions covering from visible to mid-infrared region. However, finding a suitable host of solid luminescence matrix material for its luminescence is a huge challenge at present. In this paper, a new system of oxyhalide glass based on tellurite-germanate and modified with MgCl 2 is investigated. It is worth mentioning that through the mixed structural design, the thermal properties of the matrix are further optimized, and the symmetries of the coordination structure near Ho3+ are broken, thus making a great contribution to improving Ho3+ 2–3 μm luminescence, with more than 4-fold increase in fluorescence intensities, and long fluorescence lifetime of 1.24 ms for Ho3+: 5I 7 level. The combined experimental characterizations and theoretical calculations confirm that oxyhalide glass is a very advantageous matrix material, which provides more possibilities for the application of Ho3+ in MIR lasers. [ABSTRACT FROM AUTHOR]

Transparent Tb 3+ -doped glass ceramics containing BaF 2 nanocrystals were prepared by melt-quenching method with subsequent heat treatment. The XRD and EDS results showed the precipitated crystalline phase in the glass matrix was BaF 2 . Under 376 nm light, Tb 3+ doped oxyfluoride glass ceramics containing BaF 2 nanocrystals showed more intense green emission than the as-made glass, and the emission intensity increased with increasing heat treatment temperature and time. The lifetimes of 541 nm emission of Tb 3+ doped oxyfluoride glass ceramics were longer than that of as-made glass, which are in the range from 3.00 ms to 3.55 ms. Under X-ray excitation, the green emission was enhanced in the glass ceramics compared to the as-made glass. The results indicate Tb 3+ doped oxyfluoride glass ceramics containing BaF 2 nanocrystals could be a material candidate for X-ray glass scintillator for slow event detection. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ce3+/Mn2+ doped glass-ceramics containing β-Zn2SiO4 nano-crystals were prepared. [•] The glass-ceramics showed a tunable-color emission. [•] The resonant energy transfer from Ce3+ to Mn2+ via a dipole–quadrupole mechanism. [Copyright &y& Elsevier]

Abstract: Eu2+/Ce3+ co-activated Sr3Si6O3N8 phosphor was synthesized by conventional solid-state reaction. Sr3Si6O3N8:Eu2+, Ce3+ green-emitting phosphor could be effectively excited by UV–vis light from 395 to 450nm, which matched well with the emission of UV LED chips. The luminescence intensity of Sr3Si6O3N8:Eu2+ could be efficiently enhanced by co-doping with Ce3+. The energy transfer (ET) mechanism from Ce3+ to Eu2+ in Sr3Si6O3N8:Ce3+, Eu2+ phosphors is dominated by electric dipole–dipole interaction, and the critical distance is calculated to be about 25.44Å by theory of energy transfer. [Copyright &y& Elsevier]

Abstract: A potential phosphor (Ca1−x Ba x )3(PO4)2:Eu2+ was synthesized by a solid-state reaction. X-ray diffraction (XRD) analysis confirmed the formation of (Ca1−x Ba x )3(PO4)2 crystal phase. With the Ba2+ content increasing, the bandgap of (Ca1−x Ba x )3(PO4)2 increases from 5.5 to 5.9eV, and the crystal field splitting between the two lowest Eu2+ 5d levels is enhanced from 6085 to 6808cm−1 in (Ca1−x Ba x )3(PO4)2. As a result, the emission peak of (Ca1−x Ba x )3(PO4)2: Eu2+ shifts from 447 to 550nm, which means that the emission color alters from blue to yellow. The redshift of the emission band of (Ca1−x Ba x )3(PO4)2:Eu2+ was explained based on crystal field strength, covalence, Stokes shift. The results revealed that partial substitution of Ca2+ by Ba2+ ions was therefore a much considerable way to shift the color point of LEDs. [Copyright &y& Elsevier]

Abstract: A series of phosphors with nominal compositions of Sr1.7M0.3SiO4−x F x :0.01Eu2+, 0.08Mn2+ (x=0, 0.01, 0.05, 0.1, 0.2) were synthesized through solid-state reaction technique. Their luminescent properties were studied. Three emission bands with peaks at 455, 550 and 670nm are observed in the phosphors under 380nm light excitation. When doped with fluorine, the crystal phases of the phosphors were changed slightly, while the luminescent intensities were remarkably enhanced and colorimetric parameters (chromaticity coordinates, color rendering index and color temperature) were improved. The colorimetric parameters and thermal quenching properties of Sr1.7Mg0.3SiO4−x F x :0.01Eu2+, 0.08Mn2+ phosphors with the comparison with those of commercial 467nm stimulated YAG:Ce3+ phosphors were systematically investigated. These results indicate that the phosphor with optimized composition could be a promising phosphor as a white light-emitting phosphor for near-ultraviolet light-emitting diodes. [Copyright &y& Elsevier]

Abstract: A series of Bi2O3–BaO–SiO2–RxOy (designated BiBaSi glass) glass sealants doped with different contents of TiO2 were prepared by conventional melting and annealing technique. The onset of crystallization temperature was determined by differential thermal analysis. The CTEs along with transition temperature (Tg) and softening temperature (Tf) were determined from dilatometric measurement. X-ray diffraction was used to determine the crystal phases. Scanning electron microscopy was used to study the microstructure and an associated energy dispersive X-ray spectroscopy was used to study element distribution. The good matching of thermal properties and the strong adherence to the electrolyte and connector indicate that the composite glass with 7.3mol% TiO2 (BAS3) appeared to be a good candidate for SOFC sealing. [Copyright &y& Elsevier]

Abstract: Eu2+, Mn2+ doped Sr1.7Mg0.3SiO4 phosphors were prepared by high temperature solid-state reaction method. Their luminescence properties were studied. The emission spectra of Eu2+ singly doped Sr1.7Mg0.3SiO4 consist of a blue band (455nm) and a green band (550nm). The relative intensities of two emissions varied with Eu2+ concentration. Eu2+ and Mn2+ co-doped Sr1.7Mg0.3SiO4 phosphors emit three color lights and present whitish color. The blue (455nm) and green (550nm) emissions are attributed to the transitions of Eu2+, while the red (670nm) emission is originated from the transition of Mn2+ ion. The results indicate the energy transfer from Eu2+ to Mn2+. The mechanism of the energy transfer is resonance-type energy transfer due to the spectral overlap between the emission of Eu2+and the absorption of Mn2+. [Copyright &y& Elsevier]

Abstract: Eu3+-doped Sr2Si1−x Ge x O4 (x=0–1) phosphors have been prepared by the high temperature solid-state reaction method. The luminescent properties of these phosphors were investigated. Red fluorescence of Eu3+ is enhanced gradually in the samples with increasing substitution of Si by Ge upon the excitation of 393nm light. The intensity is increased by 50% with full substitution of Si by Ge. These results are originated from the structural changes and the phonon energy reduction in the samples due to the substitution of Si by Ge. The CIE chromaticity coordinates of the phosphors vary slightly around (0.62, 0.37) and all are in the red color region. The results indicate that these phosphors could be promising red phosphors for white light emitting diodes. [Copyright &y& Elsevier]

Abstract: A blue-emitting phosphor, Eu2+-activated Mg3Ca3(PO4)4 phosphor was synthesized by conventional solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the phase formation. Photoluminescence (PL) results showed that Mg3Ca3(PO4)4: Eu2+ could be efficiently excited by UV–visible light from 250 to 430nm, which matched well with the emission wavelengths of near-UV and UV LED chips. The effects of the doped-Eu2+ concentration in Mg3Ca3(PO4)4: Eu2+ on the PL were also investigated. The result reveals that Mg3Ca3(PO4)4: Eu2+ is a potential blue-emitting phosphor for white LEDs. [Copyright &y& Elsevier]

Abstract: Eu2+ doped silicate glasses were prepared of the system 52SiO2–48MO: xEu2+(in molar ratio, M=Ca, Sr, Ba; x=1, 3, 5, 7, 9) by a high temperature melt-quenching method in a reducing atmosphere. Glass ceramics containing MSiO3:Eu2+(M=Ca, Sr, Ba) nano-phosphors were obtained after the heat treatment of the glass samples. The excitation, emission spectra and lifetime decay curves of 4f65d1→4f7 of Eu2+ were measured and interpreted with respect to their crystal structures and multi-site occupations of divalent europium in the hosts. Their excitation bands mainly extend from 450 to 250nm, which is adaptable to the main emission region of the UV LED chip. With UV light excitation, the Eu2+ emission in CaSiO3, SrSiO3 and BaSiO3 shows blue, green and yellow colors centered at 440, 505 and 555nm, respectively. The critical Eu2+concentration was studied and determined to be x=5 for both CaSiO3 and SrSiO3 and x=7 for BaSiO3 phosphors. The results show that the Eu2+ doped glass ceramic phosphors containing MSiO3 (M=Ca, Sr, Ba) nano-crystals can be used as potential matrix materials for a high power white LED pumped by the UV LED chip. [Copyright &y& Elsevier]

Abstract: A novel orange-yellow-emitting Ba2LiB5O10:Eu2+ phosphor has been synthesized by traditional high temperature solid state reaction. A monoclinic crystal structure of Barium lithiumborates Ba2LiB5O10 was verified by the investigation of X-ray diffraction (XRD). The compound crystallizes in the space group of P121/m1(11) (Z=2) with the unit cell parameters a=4.414(1)Å, b=14.576(2)Å, c=6.697(2)Å and β=104.26(2)°. Barium and lithium atoms are located in distorted octahedral and tetrahedral oxygen coordinations, respectively. Upon around 365nm excitation, the Eu2+-activated Ba2LiB5O10 phosphors exhibit a single broad emission band with the maximum at about 587nm, due to the 4f65d→4f7(8S7/2) transition of Eu2+. This work investigates the relationship between luminescence properties and structural characterization of the Ba2LiB5O10: Eu2+. This newly developed phosphor shows high potential as a phosphor conversion for white LED applications. [Copyright &y& Elsevier]

Abstract: KPb2Cl5:Mn2+ crystal with sizes of centimeters has been successfully grown by a modified Bridgman method. The electronic spectra of Mn2+ in the title compound have been measured at different temperatures and compared, revealing that the red emission observed at 10 and 77K in the spectral range from 500 to 800nm, which vanishes at room temperature, is associated with the radiation from Pb2+ ions with adjacent defects whereas the orange-red emission in the spectral range from 530 to 680nm can be undoubtedly attributed to the spin forbidden transition 4T1g (4G)→ 6A1g(6S) of Mn2+. The electronic excitation spectra are interpreted in a strong crystal field scheme with the use of the Tanabe–Sugano diagram. Good agreement with the experimental spectroscopic data is obtained with the use of crystal field splitting parameter 10Dq =7902cm−1, Racah parameters B =618cm−1, and C =3549cm−1. [Copyright &y& Elsevier]

Abstract: Ho3+/Tm3+/Yb3+ tri-doped glass ceramics with white light emitting have been developed and demonstrated. Pumped by 980nm laser diode (LD), intensive red, green and blue up-conversions (UC) were obtained. The green emission is assigned to Ho3+ ion and the blue emission is assigned to Tm3+ ion, whereas the red emission is the combination contribution of the Ho3+ and Tm3+ ions. The RGB intensities could be adjusted by tuning the rare-earth ion concentration and pump power intensity. Thus, multicolor of the luminescence, including perfect white light with CIE-X=0.329 and CIE-Y=0.342 in the 1931 CIE chromaticity diagram can be obtained in 0.15 Ho3+/0.2Tm3+/3Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals pumped by a single infrared laser diode source of 980nm at 500mW. The up-conversion luminescence mechanism of Yb3+ sensitize Ho3+ and Tm3+ ions and the energy transfer from Ho3+ to Tm3+ in oxy-fluoride silicate glass ceramics were analyzed. [Copyright &y& Elsevier]

Abstract: Eu2+/Sm3+ co-doped silicate glass was prepared by high temperature melting under reducing atmosphere and the Eu2+/Sm3+ co-doped SrSiO3 transparent glass-ceramics were obtained after heat-treatment. X-ray diffraction (XRD) and Raman spectra confirmed the formation of SrSiO3 nano-crystals in the glass matrix. The photoluminescence excitation (PLE) spectra and photoluminescence (PL) spectra of the samples were measured. A broad emission band from 400nm to 550nm due to the 4f65d1 →4f7 transitions of Eu2+ was observed, as well as several sharp emission peaks at 563nm, 600nm, 646nm and 713nm ascribed to the 4f→4f transitions of Sm3+. The luminescence properties of the glass ceramics with different molar ratio of Eu2+/Sm3+ were studied and the corresponding chromaticity coordinates were calculated. The ultraviolet light-emitting diode (UV-LED) excitable glass-ceramics emitting white light were obtained by tuning the relative emission intensity of Eu2+ and Sm3+. The results indicate that the Eu2+/Sm3+ co-doped SrSiO3 transparent glass-ceramics can be used as a potential matrix material for White LED under UV-LED excitation. [Copyright &y& Elsevier]