Search

Pr3+ doped high density germanate glasses were prepared by the melt-quenching method. The physical and luminescent properties were investigated. The glass containing BaF 2 represented maximum phonon energy of 810 cm−1, and the glass density was greater than 6 g/cm3. The glass exhibited good radiation resistance under 2 h of X-ray irradiation. Intense blue, green emissions and weak red emissions were observed when the glass was excited by X-ray, and the blue fluorescence lifetimes were in the range of 9.15–12.59 μs The results show that Pr3+ doped germanate glass could be a potential scintillating material in the field of X-ray detection for fast events. [ABSTRACT FROM AUTHOR]

Octahedral NaBi(WO4)2:Er3+/Yb3+ phosphors were synthesized by a hydrothermal method. Intense green upconversion emissions from both 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions of Er3+ ions were observed and the appropriate energy gap between them is very suitable for temperature sensing requirement based on the fluorescence intensity ratio (FIR) technique. A flexible and portable all-fiber temperature sensing device was established and used to assess the temperature sensing characteristics of NaBi(WO4)2:Er3+Yb3+ phosphors. A maximum absolute sensitivity of 0.014 K−1 is achieved at 423 K and the temperature absolute error is −0.5 K to +0.6 K. The stepwise heating and cooling processes confirm the good stability and recyclability of the all-fiber temperature sensor, which lays the foundation for actual temperature measurement. Based on the high flexibility and accuracy of the temperature sensor, the monitoring of body temperature was realized in real time and continuously, which may provide new development prospects for effective health tracking and improvement of medical care quality. [ABSTRACT FROM AUTHOR]

Europium doped borosilicate glasses were prepared in CO reducing atmosphere. The glasses were systematically investigated through XPS, photoluminescence (PL), fluorescence decay curves and X-ray excited luminescence (XEL). XPS results show that the glasses contain Eu2+ and Eu3+ at the same time. Under the excitation of 360 nm light, only a broad blue emission with peak around 440 nm due to the 5d→4f transition of Eu2+ is observed, while the emissions from Eu3+ do not appear in the PL spectra. The fluorescence decay curves were monitored at 440 nm, and the measured lifetimes are in the range of 0.17–0.42 μs. The PL results indicate that the PL emission from Eu2+ is significantly intense than the PL emissions from Eu3+. Upon X-ray excitation, two main emissions with peaks at 445 nm and 616 nm corresponding to Eu2+ and Eu3+ are obtained. The XEL results reveal that the XEL emissions from Eu3+ are comparably intense as the XEL emission from Eu2+. The results indicate that europium doped borosilicate glass could be a potential scintillating material in X-ray detection filed. [ABSTRACT FROM AUTHOR]

Tb3+‐doped germanate glass ceramics containing CaF2 nanocrystals were prepared by melt quenching method with subsequent heat treatment. Their microstructures were investigated by XRD and TEM techniques. Their optical properties were studied by the transmittance, the photoluminescence, and the X‐ray excited luminescence (XEL). The luminescence intensity in the glass ceramics under 377 nm light and X‐ray excitations is significantly enhanced. The maximum integrated XEL intensity of the glass ceramics is about 50% of that of the commercial Bi4Ge3O12 (BGO) scintillating crystal. The results indicate that Tb3+‐doped germanate glass ceramic could be a promising scintillating material used in X‐ray detection for slow event. [ABSTRACT FROM AUTHOR]

Abstract Eu3+ doped tellurite scintillating glasses were prepared by the conventional melt-quenching method. The physical and luminescent properties of glasses were investigated by DTA, density, transmittance spectra, photoluminescence spectra, and X-ray excited luminescence (XEL) spectra. The densities of the glasses are in the range from 5.89 g/cm3 to 6.05 g/cm3. The glasses exhibit intense red emissions upon 393 nm light and X-ray excitations. The maximum integral XEL intensity of the glasses is about 6% of that of commercial Bi 4 Ge 3 O 12 (BGO) scintillating crystal. The results reveal that Eu3+ doped tellurite glass could be a scintillator candidate used in X-ray detection field. [ABSTRACT FROM AUTHOR]

Er3+ doped high density germanate glasses with compositions of 50GeO 2 -10BaO–10Al 2 O 3 -15Lu 2 O 3 -(15-x) La 2 O 3 -xEr 2 O 3 (x = 0, 0.1, 0.5, 1.0, 1.5, and 2.0, in mol%) have been prepared by the melt-quenching method. The optical and physical properties of the samples were characterized by differential scanning calorimetry (DSC), density, transmittance spectra, photoluminescence (PL) spectra, and X-ray excited luminescence (XEL) spectra. The densities were in the range from 5.90 to 6.07 g/cm3. The strong green emissions around 552 nm of Er3+ were observed upon the excitations of 378 nm light and the X-ray, and the lifetimes of 552 nm emission were in the range of 20.88–96.47 μs. The results show that Er3+ doped high density germanate glasses could be used as potential scintillators for X-ray CT. [ABSTRACT FROM AUTHOR]

Cubic-to-hexagonal phase evolution, narrow crystalline size distribution and enhancement of luminescence are simultaneously achieved by modifying the ratio of SiO2/B2O3 content in the Eu3+-doped oxyfluoride borosilicate glass ceramics containing NaGdF4 nanocrystals. The mechanisms of phase evolution of NaGdF4 nanocrystals are discussed on the basis of IR spectra, viscosity, XRD and TEM data. The results indicate that the stresses developed during the thermal treatment process play an important role in the phase evolution, which provides an experimental evidence of pressure-induced disorder-to-order phase evolution during the crystallization process for the first time. It is also found that the excitation and emission spectra as well as the luminescence lifetimes of the Eu3+ ions in the oxyfluoride glass ceramic are sensitive to the crystal lattice of NaGdF4. [ABSTRACT FROM AUTHOR]

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: 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: Transparent oxyfluoride glasses doped with Tb3+ were prepared by melt quenching method. The transmittance spectra show the glasses have good transmittance in the visible spectrum region. The emission spectra under 376nm light and X-ray excitations were recorded. Tb3+ doped oxyfluoride glasses show intense green emissions under both excitations. The optimum concentrations of Tb3+ ion are around 8mol% and around 10mol% under 376nm light excitation and X-ray excitation, respectively. The lifetimes of 541nm emission of oxyfluoride glasses doped with Tb3+ are in the range from 2.65ms to 3.02ms. The results indicate that Tb3+-doped oxyfluoride glasses could be an X-ray scintillating material suitable to X-ray detection for slow event. [Copyright &y& Elsevier]

Ce3+ activated high-density lanthanum lutetium germanate glass was fabricated by melt quenching method. Their densities, fluorescence decay curves, transmittance spectra, and luminescence excited by UV light and X-ray were measured and investigated. The densities of the glasses are between 5.90 g/cm3 and 5.97 g/cm3. The glasses present blue emission upon 379 nm light and X-ray. The blue emission lifetimes of the glasses are between 11.26 ns and 18.83 ns. The results shows that Ce3+ activated high-density lanthanum lutetium germanate glass would be a potential fast-event X-ray detection scintillating material. • Ce3+ doped germanate glasses with density around 6 g/cm3 were prepared. • The glass showed blue emissions upon UV light and X-ray. • The blue emission lifetimes were in the range of 11.26–18.83 ns. [ABSTRACT FROM AUTHOR]

The influence of Li+/Zn2+ heterovalent doping on the structural change and upconversion luminescence properties of Lu 2 W 2.5 Mo 0.5 O 12 :Er3+/Yb3+ phosphors was investigated in details. The gradual substitution of Li+/Zn2+ ions for Lu3+ ions result in the evolution from orthorhombic Lu 2 W 2.5 Mo 0.5 O 12 to monoclinic (LiZn) 2 W 2.5 Mo 0.5 O 12 , which bring the structural distortion, the reduction of local symmetry and the crystallite growth. The green upconversion intensity of Er3+ ions at 536 nm and 550 nm were enhanced significantly by a factor of 8000 and 4000. The temperature sensing characteristics of a single (LiZn) 2 W 2.5 Mo 0.5 O 12 :Er3+/Yb3+ particle in all-fiber structure was explored and the unusual thermally-enhanced upconversion luminescence was observed, which is beneficial for achieving high-precision temperature measurement based on the fluorescence intensity ratio technology. The absolute temperature sensitivity reached a maximum of 0.0095 K−1 at 423 K and the temperature deviation was less than 0.6 K. The as-built all-fiber temperature sensor was successfully applied in the on-line monitoring of CPU temperature. [ABSTRACT FROM AUTHOR]

Abstract: A new Er3+ doped oxyfluoride borosilicate glass ceramics was developed by controlling crystallization of the quenched glass. The hexagonal NaGdF4 nanocrystals were precipitated in the glass matrix, which was confirmed by the X-ray diffraction and TEM results. Notable enhancement of upconversion emission was observed in the Er3+ doped glass ceramics and attributed to the enrichment of Er3+ into NaGdF4 nanocrystals. With the increasing of Er3+ content, the upconversion emission density ration from green to red light greatly changed in the glass ceramics. This material may be used as a potential material for the silicon solar cells. [Copyright &y& Elsevier]

Lanthanide-doped oxide materials generally require high sintering temperatures for optical applications such as temperature sensing and anti-counterfeiting. In this work, the highly crystalline 1%Pr3+/1%Er3+ co-doped Bi 2 Mo 2 O 9 phosphor is reported with a low sintering temperature of 923 K. Pr3+ in the Bi 2 Mo 2 O 9 host has a narrow emission band of 3P 0 –3H 6 transition at 624 nm due to the suppressed broadening of electronic transitions in the homogeneous crystal field. Multimode temperature sensing is realized based on the upconversion and downshifting emissions as well as the luminescence lifetimes of the as-prepared phosphor. The temperature sensing based on the downshifting emission bands of this phosphor at 530 and 624 nm achieves the maximum absolute and relative sensitivities of 0.693 K−1 at 568 K and 1.88% K−1 at 483 K, respectively. For anti-counterfeiting applications, this phosphor can display bright yellow fluorescence at the liquid nitrogen cooling temperature, rather than white or pale colors. The white-color emission of this phosphor excited by 254 nm can also be used for lighting. The lanthanide-doped Bi 2 Mo 2 O 9 can achieve favorable luminescence performance at much lower sintering temperature than most oxide phosphors, and is not only stable but also has the potential for in-situ sintering on materials that are not resistant to high temperature. • The Bi 2 Mo 2 O 9 :Pr3+/Er3+ phosphor can be synthesized at low temperature of 923 K. • Temperature sensing is studied based on downshifting and upconversion emissions and luminescence lifetimes. • The highest absolute and relative sensitivities are 0.693 K−1 at 568 K and 1.88% K−1 at 483 K, respectively. • Multicolor photoluminescence is realized under 254/365 nm excitation for anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The crystal phase evolution from cubic α-NaYF 4 to hexagonal β-NaYF 4 was achieved in transparent oxyfluoride glass ceramics by modifying glass composition and rare earth doping. It was found that the development of compressive stress during the crystallization process may be responsible for the formation of β-NaYF 4 nanocrystals. The incorporation of Eu 3+ ions into the precipitated NaYF 4 nanocrystals was verified and the difference of the distribution of Eu 3+ ions in the glass ceramics resulted in remarkable changes in the emission spectra, such as the relative emission intensity, Stark splitting and fluorescence decay lifetimes. Bright and efficient upconversion luminescence was observed in the Er 3+ /Yb 3+ co-doped glass ceramics and the corresponding upconversion mechanisms were analyzed. [ABSTRACT FROM AUTHOR]

Dy 3+ /Tm 3+ co-doped oxyfluoride glass ceramics containing hexagonal β-NaGdF 4 nanocrystals were prepared by the melt-quenching method and subsequent heat-treatment procedure. During the crystallization process, the structural evolution of glass network was systematically investigated using XRD, TEM and FTIR spectra. Experimental results provided new evidences that a silica-enriched layer around the precipitated fluoride nanocrystals was formed during the crystallization process. Strong white light emission was obtained in the oxyfluoride glass ceramics by modifying the relative concentration ratio of Tm 3+ and Dy 3+ ions. [ABSTRACT FROM AUTHOR]

Abstract: Rare earth ions (Ln3+) doped optical materials manifest sharp and tunable emission, high photostability, long luminescent lifetime and low cytotoxicity, and find diverse applications in optics, optoelectronic devices and bio-labelling. Herein, we employed a conventional hydrothermal approach to control the size and tune the phase as well as the morphology of GdF3:Tb3+,Yb3+ nanocrystals, wherein the effects of the synthetic conditions, such as pH, time, the ratio of the Gd to F and the surfactant, have been detailed investigated, producing sphere, platelet, rice, flower-shaped GdF3 nanoparticles. Diffuse reflectance spectra, photoluminescence emission and excitation spectra, and photoluminescence lifetime measurements were employed to characterize the optical spectroscopic properties of GdF3:Tb3+,Yb3+ nanocrystals. No efficient energy transfer from Tb3+ to Yb3+ is observed in GdF3:Tb3+,Yb3+ nanocrystals and the Yb3+ shows a concentration quenching effect at high doping levels. [Copyright &y& Elsevier]

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: The influence of LaF3 on the crystallization behavior and luminescence of Eu3+ ions in the oxyfluoride borosilicate glass ceramics was investigated in details. Differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) results indicated that the addition of LaF3 decreased the glass transition temperature and promoted the crystallization of BaF2 nanocrystals, which distributed homogeneously in the glassy matrix. A reduction of the lattice parameters of BaF2 nanocrystals, the obvious Stark splitting of emission peaks and long fluorescence lifetime evidenced the incorporation of Eu3+ and La3+ into the BaF2 lattice. Furthermore, experimental results indicated the distribution of Eu3+ ions in the oxyfluoride glass ceramics may be modified by the addition of LaF3 content. [Copyright &y& Elsevier]

• Lanthanide metal ions doped NaLa(WO 4) 2 :glass ceramics were fabricated. • The enhancement of upconversion and near-infrared emissions of Er3+ ion was observed. • A high temperature sensitivity s a of 0.014 K −1 is achieved at 476 K. Eu3+ doped and Er3+/Yb3+ codoped glass ceramics containing NaLa(WO 4) 2 nanoparticles have been prepared and their optical and temperature sensing properties have been investigated. Strong diffraction peaks and elliptical NaLa(WO 4) 2 nanoparticles with well-defined lattice stripes are observed in the X-ray diffraction and transmission electronic microscope results, respectively. Great enhancement of the photoluminescence intensity of Eu3+ ions is observed owing to the selective entering of Eu3+ ions into the precipitated NaLa(WO 4) 2 nanoparticles. The improvement of visible upconversion emissions and near-infrared photoluminescence emissions of Er3+/Yb3+ ions are also attributable to the enrichment of Er3+/Yb3+ ions in the low phonon-energy NaLa(WO 4) 2 nanoparticles. The temperature dependence fluorescence intensity ratio was investigated and the temperature sensing characteristics was evaluated. The maximum temperature sensitivity S a is 0.014K−1 at 476 K, which demonstrates Er3+/Yb3+ codoped NaLa(WO 4) 2 :glass ceramic is one of the candidates for new optical temperature-sensing application. [ABSTRACT FROM AUTHOR]

Abstract: Er3+-doped transparent oxyfluoride borosilicate glass ceramics containing LaOF nanocrystals have been obtained by the high temperature melt-quenching and subsequent heat treatment method. The formation of LaOF nanocrystals in the glass matrix was confirmed by XRD and TEM results. In comparison with the precursor glass, Er3+-doped transparent oxyfluoride glass ceramics containing LaOF nanocrystals exhibited efficient up-conversion luminescence. Especially, the green emission intensity was greatly enhanced about nearly 200 times and its up-conversion mechanism can be ascribed to a two-photon absorption process. [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: Transparent oxyfluoride borosilicate glass ceramics containing Ba2+1.5x Yb1−x F7:Tb3+ nanocrystals were successfully prepared by a melt-quenching method with subsequent heat treatment. The precipitated crystalline phase in the glass matrix changed gradually from BaF2 to Ba2+1.5x Yb1−x F7 with the increase of YbF3 content, which was confirmed by the results of XRD, HRTEM and EDX measurements. The ultraviolet and visible up-conversion and near-infrared quantum cutting down-conversion emissions were observed and interpreted. These materials could be used to modify the solar spectrum and enhance the silicon solar cell efficiency by the up-conversion and down-conversion luminescence of Tb3+–Yb3+ couples in the oxyfluoride borosilicate glass ceramics. [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: Eu/Tb codoped transparent oxyfluoride borosilicate glass ceramics containing Sr2GdF7 nanocrystals were fabricated under a reductive atmosphere and the conversion of Eu3+ ions to Eu2+ ions was observed. The Sr2GdF7 nanocrystals with an average size of 32nm were homogeneously precipitated in the oxyfluoride borosilicate glass matrix, which could be evidenced by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy. The enhancement of photoluminescence emission intensity, reduction of the relative emission intensities between 5D0 → 7F2 and 5D0 → 7F1, and long fluorescence lifetimes of Eu2+, Eu3+, and Tb3+ ions revealed that more rare earth ions were partitioned into the low phonon energy environment Sr2GdF7 nanocrystals. Under ultraviolet excitation, pure and bright white light emission was obtained in the oxyfluoride borosilicate glass ceramic, which may be a potential blue, green and red-emitting phosphor for white LEDs. [Copyright &y& Elsevier]

Abstract: Eu/Tb codoped aluminoborosilicate glasses were fabricated by high temperature melting-quenched technique and their luminescence properties were investigated by excitation and emission spectra. Under 376nm excitation, blue, green and red emission bands were simultaneously observed at 425nm, 485nm, 540nm and 611nm, respectively. The broad blue emission band centered at 425nm was originated from the reduced Eu2+ ions, which were reduced from Eu3+ ions at high temperature in an ambient atmosphere and the reduction process may be related with the optical basicity of glass matrix. A complex bright white light emission was obtained for 0.5mol% Eu2O3, 0.5mol% Tb2O3 codoped aluminoborosilicate glass with CIE-X=0.31 and CIE-Y=0.33. The energy transfer among Eu3+, Eu2+ and Tb3+ ions was also discussed. [Copyright &y& Elsevier]

Abstract: Transparent Ni2+-doped SiO2-Al2O3-Ga2O3-Li2O (LGAS) glass–ceramics embedding lithium aluminate spinel nanocrystals was prepared. After heat treatment, LiAl5O8 crystallite was precipitated in the glasses, and its size was about 3nm. It was confirmed from the absorption spectra that the ligand environment of Ni2+ ions changed from the trigonal bi-pyramid fivefold sites in the as-made glass to the octahedral sites in the glass–ceramics. Upon excitation at 980nm, broadband infrared luminescence centered at around 1250nm with full width at half maximum (FWHM) more than 250nm was observed originating from the 3 T 2(3 F) → 3 A 2(3 F) transition of Ni2+ in octahedral sites. The broadband near-infrared (NIR) emission from Ni2+-doped glass–ceramics can be as host materials for broadband optical amplifier. [Copyright &y& Elsevier]

Abstract: Transparent Eu2+/Mn2+ co-doped new glass ceramics (GC) containing β-Zn2SiO4 nanocrystals were prepared under a reduced atmosphere. The optical properties of these samples have been investigated. The emission spectra of Eu2+/Mn2+ co-doped glass ceramics show two broadband peakings at 458 and 560nm under ultraviolet radiation, which can be attributed to 4f 65d 1→4f 7 transition of Eu2+ and 4 T 1(4 G)→ 6 A 1(6 S) transition of Mn2+, respectively. Energy transfer (ET) from Eu2+ to Mn2+ is discovered by directly observing significant overlap of the excitation spectrum of Mn2+ and the emission spectrum of Eu2+. ET from Eu2+ to Mn2+ in glass ceramics is further confirmed by fluorescence studies performed on the samples with various activator (Mn2+) concentrations. The optimal composition generates white light with chromaticity coordinates (0.291, 0.344). The results indicate that Eu2+/Mn2+ co-doped glass ceramics is potential material for white light-emitting diodes (LEDs). [ABSTRACT FROM AUTHOR]

Great improvement of upconversion luminescence in Lu 2 MoO 6 :Er3+/Yb3+ phosphor is observed due to the introduction of Li+ ions and a highly sensitive all-fiber optical temperature measurement platform is established. X-ray diffraction (XRD) results show that pure Lu 2 MoO 6 :Er3+/Yb3+ phase has been prepared and Li 2 CO 3 dramatically promotes the growth of Lu 2 MoO 6 :Er3+/Yb3+ phase in the scanning electron microscope(SEM) images. In comparison to the sample without Li+ ions, green upconversion luminescence intensity was increased by 516 times. The maximum absolute sensitivity of 0.015 K−1 is achieved at 423 K and temperature measurement error is ±0.8 K. The experimental results lay the foundation for the practical application of the ratiometric all-fiber optical temperature sensor. [ABSTRACT FROM AUTHOR]

Abstract: Ce3+ doped La4Ca(SiO4)3O phosphors with silicate oxyapatite structure were synthesized by the sol-gel process. The X-ray diffraction (XRD) patterns showed that a pure phase was formed when sintering temperature was higher than 1300°C. The optical properties of La4Ca(SiO4)3O:Ce3+ phosphors with varying sintering temperature and concentration were investigated by examining their excitation and emission spectroscopy. The phosphors exhibited a broad emission band centered at 550nm which could be attributed to the 5d-4f transition of Ce3+ and a stronger excitation peak around 467nm as well as several shoulder bands, nicely matching with the widely applied blue LED chips. Higher emission intensity was observed when firing temperature above 1300°C, due to increasing crystallinity of the powders. When Ce3+ concentration was equal to 5 at%, the sample exhibited the optimum excitation and emission efficiency. The results indicate that La4Ca(SiO4)3O:Ce3+ is a promising candidate in the application of blue chip excited white light emitting diodes (LEDs). [Copyright &y& Elsevier]

Abstract: Y6Si3O9N4:Ce3+ phosphor was prepared by a solid-state reaction in reductive atmosphere. X-ray powder diffraction (XRD) analysis confirmed the formation of Y6Si3O9N4:Ce3+. Scanning electron microscopy (SEM) observation indicated that the microstructure of the phosphor consisted of irregular fine grains with an average size of about 5μm. Photoluminescence (PL) measurements showed that the phosphor can be efficiently excited by near ultraviolet (UV) or blue light excitation, and exhibited bright green emission peaked at about 525nm. Compared with Ce3+-doped Y4Si2O7N2 phosphors, Ce3+-doped Y6Si3O9N4 phosphors showed longer wavelengths of both excitation and emission. The Y6Si3O9N4:Ce3+ is a potential green-emitting phosphor for white LEDs. [Copyright &y& Elsevier]