Tianjin Key Laboratory for Photoelectronic Materials and Devices

Tianjin, China

Tianjin Key Laboratory for Photoelectronic Materials and Devices

Tianjin, China
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Qiu K.,Tianjin University of Technology | Tian H.,Tianjin University of Technology | Song J.,Tianjin University of Technology | Mao Z.,CAS Shanghai Institute of Ceramics | And 3 more authors.
Journal of Rare Earths | Year: 2012

Europium-doped borosilicate glasses were prepared by melt-quenching procedure in the air. The mixed valence of Eu 2+ and Eu 3+ was identified by photo luminescence spectrum and electron paramagnetic resonance (EPR). The existence of mixed valence was observed owing to the unequivalent substitution and de-polymerization network of the as-prepared borosilicate glasses. The variation of the glass composition in B 2O 3/BaO ratios changed the stability of the Eu 3+ ions distinctly. In particular, as-prepared borosilicate glasses exhibited a tri-wavelength light excitable spectra centered at 397, 466 and 534 nm to give the broadened orange-red emission at around 592 and 617 nm, due to supersensitive transitions of Eu 3+ ions. This simultaneous tri-wavelength excitation happened to correspond with the emitting wavelength from near ultraviolet, blue AlInGaN chips and that from YAG:Ce 3+. The total quantum yield (QY) of the Eu-doped glasses under 466 nm excitation was evaluated to be 10, potentially providing a versatile combination with the europium-doped borosilicate glasses for red component addition to improve the quality of white light. © 2012 The Chinese Society of Rare Earths.


Ma J.,Tianjin University of Technology | Lu Q.-F.,Tianjin University of Technology | Lu Q.-F.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Wang Y.-Z.,Tianjin University of Technology | And 5 more authors.
Chinese Physics B | Year: 2014

We report a novel approach to obtaining a classical blue-green excitable CaS:Eu2+ phosphor with desired red emission by microwave (MW) firing procedure in the absence of adding elemental sulphur. The disturbing effect of MW electromagnetic field on decomposition of CaSO4 into CaS activated by europium is distinctly observed to give pure host phase without adding any elemental sulphur and carbon. The host phase evolution is observed to be highly dependent on the variation of applied MW power from X-ray diffraction (XRD) patterns and the corresponding photoluminescence (PL), and a maximum PL intensity at 1100 W of MW power is acquired for the obtained purer host phase. The non-thermal and non-equilibrium effects by MW are revealed to correlate with the interaction between polar structure of the host and applied electromagnetic field. The results demonstrate an optional procedure to prepare this red-emitting phosphor in an effective, environment-friendly and scalable approach for phosphor production in the application of bio-illumination for plant cultivation and artificial photosynthesis. © 2014 Chinese Physical Society and IOP Publishing Ltd.


Cai Y.,Tianjin University of Technology | Lu Q.-F.,Tianjin University of Technology | Lu Q.-F.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Li J.,Tianjin University of Technology | And 5 more authors.
Electrochemical and Solid-State Letters | Year: 2012

The simultaneous emission of 440 nm-peaked blue and 619 nm-peaked red of Ba 3MgSi 2O 8:Eu 2+, Mn 2+ was enhanced by the metal-enhanced fluorescence (MEF) through assembling sliver island films for photosynthetic action spectrum (PAS). A 1.42-fold enhancement of blue emission was resulted from MEF-induced resonant coupling between the localized surface plasmon of Ag and the photons of blue emission from Eu 2+. Sequentially, this enhanced photonic energy of blue emission was transferred to the co-activator of Mn 2+, leading to a 1.47-fold intensification of red emission. The dual enhanced emission of PAS could be optimized to a maximum with an annealed 50-nm-thick silver film. © 2011 The Electrochemical Society.


Lu Q.-F.,Tianjin University of Technology | Lu Q.-F.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Li J.,Tianjin University of Technology | Wang D.-J.,Tianjin University of Technology | Wang D.-J.,Tianjin Key Laboratory for Photoelectronic Materials and Devices
Current Applied Physics | Year: 2013

A single-phased (Ba,Sr)3MgSi2O8:Eu 2+, Mn2+ phosphor with 660 nm-featured dual band-emission is investigated upon optimizing composition to simulate the artificial photosynthetic action spectrum (PAS) for near-ultraviolet (NUV) biological light-emitting diodes (bio-LEDs). A specific composition range in Ba -Sr binary solid solution of (Ba,Sr)3MgSi2O8 is found to be capable of obtaining single-phased host in the absence of an easily formed orthosilicate impurity, leading to a 660 nm-featured red band emission of Mn2+ induced by an efficient energy transfer from a co-doped blue-emitting Eu2+ sensitizer. This dual broad band emission phosphor has a 72 nm full width at half maximum (FWHM) for red band that covers fairly well to the absorption spectrum of chlorophyll and PAS for most plants, enabling a flexible option in the application of bio-illumination for artificial photosynthesis. © 2013 Elsevier B.V. All rights reserved.


Wang P.,Tianjin University of Technology | Wang D.-J.,Tianjin University of Technology | Wang D.-J.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Song J.,Tianjin University of Technology | And 3 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2012

The role of Si 4+ in the valence state of Ce and phase control in YAG:Ce phosphors was investigated upon incorporation of Si-O in the form of SiO 2. By varying the amount of SiO 2 addition, the valence state of tetravalent and trivalent Ce ions was identified distinctly by X-ray photoelectron spectroscopy and the phase purity of YAG host phase was examined by X-ray diffraction patterns. The self-reduction phenomena from Ce 4+ to Ce 3+ in YAG:Ce samples was observed to be featured in a typical 5d → 4f yellow-green transition of Ce 3+ ion upon firing in air, driven by charge compensation for imbalance substitution of Ce 4+ for Y 3+. The addition of SiO 2 promotes further reduction of Ce 4+ to Ce 3+ in an amount up to 7.0 wt%, owing to spontaneous charge compensation, and suppresses the formation of YAP (yttrium aluminate perovskite, YAlO 3) and YAM (yttrium aluminate monoclinic, Y 4Al 2O 9). The results reveal the role of SiO 2 addition in a proper amount to be able to achieve desired luminous center of Ce 3+ and phase-pure YAG for a series of YAG hosted luminescence materials such as blue-excitable YAG phosphor or laser-pumped YAG-based transparent ceramics or glass ceramics for lighting and display purposes. © Springer Science+Business Media, LLC 2012.


Cao L.-S.,Tianjin University of Technology | Lu Q.-F.,Tianjin University of Technology | Lu Q.-F.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Wang L.-C.,Tianjin University of Technology | And 4 more authors.
Ceramics International | Year: 2013

The 660 nm-featured (Ba, Sr) 3MgSi2O 8:0.06Eu2 +, 0.1Mn2+(AMS-EM) phosphor in violet for red/blue bio-lighting LEDs was prepared by 2.45 GHz microwave (MW) high temperature firing procedure. The phase-pure host phase, (Ba, Sr) 3MgSi2O8, was formed to be responsible for simultaneous red band emission from Mn ion and blue band emission from Eu ion, while the formation of an impurity phase of Sr2SiO4 responsible for 505 nm-peaked green band emission for Eu ion was effectively suppressed owing to MW fast-heating procedure. Small sized and agglomeration-free phosphor particles were either observed, which was probably resulted from suppressing the grain growth in as-formed host particles, compared with conventional high-temp solid state (SS) reaction firing procedure. These results indicate that high-temp MW firing procedure is suitable for preparing this simultaneously red- and blue-emitting AMS-EM phosphor in the application of bio-lighting for plant cultivation. © 2013 Elsevier Ltd and Techna Group S.r.l.


Lu Q.-F.,Tianjin University of Technology | Li J.,Tianjin University of Technology | Wang D.-J.,Tianjin University of Technology | Wang D.-J.,Tianjin Key Laboratory for Photoelectronic Materials and Devices
ECS Solid State Letters | Year: 2012

Intensification of the photosynthetic action spectrum (PAS) of Ba 3MgSi2O8:Eu2+, Mn2+ (BMS-EM) with a simultaneous emission peaked at 620 nm and 430 nm is investigated via template-free spray pyrolysis (SP) followed by post-annealing. The cage-like sphere of phase-pure BMS-EM with a nano-porous shell composed of building blocks of nanocrytals, exhibits a high harvesting of incident photonic energy as verified with Diffuse Reflection Spectra (DRS) and microscopic observation, respectively. The enhanced emission of BMS-EM, which is related to the light-trapping effect, shows great promise to improve the eco-lighting devices currently used for plant cultivations. © 2012 The Electrochemical Society.


Zheng X.,Tianjin University of Technology | Fei Q.,Tianjin University of Technology | Mao Z.,Tianjin University of Technology | Liu Y.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | And 5 more authors.
Journal of Rare Earths | Year: 2011

Photoluminescence (PL) and colorimetric properties of white-light emission SrAl2Si2O8:Eu2+,Mn2+ phosphor were tuned effectively through incorporating Si-N bond to the host in the form of Si3N4. A maximum solubility of Si-N bond in SrAl2-xSi2+xO8-xNx was estimated theoretically to be in a value of x=1.0. Under 365 nm irradiation, a distinct red-shift of blue band emission from 406 to 473 nm for Eu2+ and an enhancement of yellow band emission peaked at ∼565 nm for Mn2+ were observed with the increase of Si-N content. These effects resulted from partial substitution of Si-N for Al1-O1 and Al4-O2 sites in SrAl 2Si2O8 lattice. Eventually, a white emission with CIE chromaticity coordinates (0.287, 0.337) and color rendering index (CRI) 78.3 for SrAl2Si2O8:Eu2+,Mn 2+ phosphor were achieved upon optimization to a suitable amount of Si-N. © 2011 The Chinese Society of Rare Earths.


Tian H.,Tianjin University | Tian H.,Tianjin University of Technology | Tian H.,Tianjin Key Laboratory for Photoelectronic Materials and Devices | Wang D.-J.,Tianjin University of Technology | And 4 more authors.
Faguang Xuebao/Chinese Journal of Luminescence | Year: 2011

Calcium silicate glass-ceramic phosphor with green emission was evaluated. The effect of crystals precipitation microstructure on spectral properties was investigated by changing the holding time at melting temperature. With the in crease of holding duration, the amount ratio of luminous β-Ca 2SiO 4:Eu 2+ crystalline phase to glassy phase tended to be decreased, leading to a red-shift of the emission band and exhibiting more transparent of the glass-ceramic phosphor. The precipitation of SiO 2 crystals in priority was proposed. The broad excitation band of the green-emitting glass-ceramic phosphors covers the wavelength from 270 to 440 nm, showing the potential for the high-power phosphor-converted LED.

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