The Experts below are selected from a list of 150 Experts worldwide ranked by ideXlab platform
Mingying Peng - One of the best experts on this subject based on the ideXlab platform.
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Phosphor coated NiO-based planar inverted organometallic halide perovskite solar cells with enhanced efficiency and stability
Applied Physics Letters, 2016Co-Authors: Jin Cui, Zhifan Chen, Kun Cao, Junbo Han, Yan Shen, Mingying Peng, Mingkui WangAbstract:This work investigates non-Rare-Earth Phosphor (Sr4Al14O25:Mn4+, 0.5%Mg) with intensively red luminescence as a luminescent down-shifting layer for perovskite solar cells. The power conversion efficiency of the fabricated device with a structure of NiO/CH3NH3PbI3/[6,6]-phenyl C61-butyric acid methyl ester/Au coated with Phosphor layer shows a 10% increase as compared with that of the control devices. Importantly, the Phosphor layer coating can realize UV-protection as well as waterproof capability, achieving a reduced moisture-degradation of CH3NH3PbI3 perovskite upon applying an UV irradiation. Therefore, perovskite devices using this luminescent coating show a combined enhancement in both UV down-shifting conversion and long term stability. This can be expanded as a promising encapsulation technique in the perovskite solar cell community.
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site occupancy preference enhancement mechanism and thermal resistance of mn4 red luminescence in sr4al14o25 mn4 for warm wleds
Chemistry of Materials, 2015Co-Authors: Mingying Peng, Peter A Tanner, M G Brik, Pengfei LiAbstract:Red Phosphors play an indispensable role in Phosphor-based warm white light-emitting diodes (WLEDs). We demonstrated recently that the non-Rare-Earth Phosphor Sr4Al14O25:Mn4+ exhibits red luminescence even more intensely than the commercial Mn4+ Phosphor 3.5MgO.0.5MgF2.GeO2:Mn4+ upon blue excitation. Herein, on the basis of crystal field calculations employing the exchange charge model, we identify the energy levels of three types of Mn4+ ions situated at Al3+ sites in the Sr4Al14O25 crystal lattice and find that the doped manganese ions occupy preferentially the Al4 and Al5 more covalent sites rather than the Al6 site. We report that the Mn4+ luminescence can be enhanced upon the inclusion of Mg2+ in the synthesis reaction. The mechanisms for this effect comprise the lower nonradiative decay rate from the 2Eg state because of the reduction in energy migration along Mn4+ ions to killer sites and the morphology evolution from orderly layered smooth nanosheets to irregular nanoparticles disorderly compacted...
Shengen Zhang - One of the best experts on this subject based on the ideXlab platform.
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an alkaline fusion mechanism for aluminate Rare Earth Phosphor cation oxoanion synergies theory
Rare Metals, 2019Co-Authors: Yifan Liu, Shengen Zhang, Bo Liu, Hanlin ShenAbstract:Waste aluminate Rare Earth Phosphor is an important Rare Earth elements (REEs) secondary resource, which mainly consists of BaMgAl10O17:Eu2+ (BAM) and CeMgAl11O19:Tb3+ (CMAT). Alkaline fusion process is widely used to recycle REEs from aluminate Phosphor, but the related theory remains imperfect. In this paper, a series of alkaline fusion experiments of CMAT were performed to describe the phase change law of CMAT reactions. Based on comprehensive analysis, cation–oxoanion synergies theory (COST) was proposed to explain the aluminate Phosphor structure damage. On the mirror plane of aluminate Phosphor crystal structure, alkali metal cations (Na+, K+) would substitute Rare Earth ions, while free oxoanion (OH−, CO32−, O22−) can combine with Rare Earth ions. These two ionic forces ensure that Rare Earth ions can be substituted by cations. Then, the structure is decomposed. Morphological analysis shows that observable expression of COST can be described by shrinking core model after simplification. Reaction rate constant calculated indicates that the reaction degree is nanometers per second. COST provides a more complete mechanism, and it can help improve Rare Earth recycling technology furtherly.
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An alkaline fusion mechanism for aluminate Rare Earth Phosphor: cation–oxoanion synergies theory
Rare Metals, 2017Co-Authors: Yifan Liu, Shengen Zhang, Bo Liu, Hanlin ShenAbstract:Waste aluminate Rare Earth Phosphor is an important Rare Earth elements (REEs) secondary resource, which mainly consists of BaMgAl10O17:Eu2+ (BAM) and CeMgAl11O19:Tb3+ (CMAT). Alkaline fusion process is widely used to recycle REEs from aluminate Phosphor, but the related theory remains imperfect. In this paper, a series of alkaline fusion experiments of CMAT were performed to describe the phase change law of CMAT reactions. Based on comprehensive analysis, cation–oxoanion synergies theory (COST) was proposed to explain the aluminate Phosphor structure damage. On the mirror plane of aluminate Phosphor crystal structure, alkali metal cations (Na+, K+) would substitute Rare Earth ions, while free oxoanion (OH−, CO32−, O22−) can combine with Rare Earth ions. These two ionic forces ensure that Rare Earth ions can be substituted by cations. Then, the structure is decomposed. Morphological analysis shows that observable expression of COST can be described by shrinking core model after simplification. Reaction rate constant calculated indicates that the reaction degree is nanometers per second. COST provides a more complete mechanism, and it can help improve Rare Earth recycling technology furtherly.
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Rare Earth elements recycling from waste Phosphor by dual hydrochloric acid dissolution
Journal of Hazardous Materials, 2014Co-Authors: Shengen Zhang, Jianjun Tian, Min Yang, Maolin Wu, Alex A. VolinskyAbstract:Abstract This paper is a comparative study of recycling Rare Earth elements from waste Phosphor, which focuses on the leaching rate and the technical principle. The traditional and dual dissolution by hydrochloric acid (DHA) methods were compared. The method of dual dissolution by hydrochloric acid has been developed. The Red Rare Earth Phosphor (Y0.95Eu0.05)2O3 in waste Phosphor is dissolved during the first step of acid leaching, while the Green Phosphor (Ce0.67Tb0.33MgAl11O19) and the Blue Phosphor (Ba0.9Eu0.1MgAl10O17) mixed with caustic soda are obtained by alkali sintering. The excess caustic soda and NaAlO2 are removed by washing. The insoluble matter is leached by the hydrochloric acid, followed by solvent extraction and precipitation (the DHA method). In comparison, the total leaching rate of the Rare Earth elements was 94.6% by DHA, which is much higher than 42.08% achieved by the traditional method. The leaching rate of Y, Eu, Ce and Tb reached 94.6%, 99.05%, 71.45%, and 76.22%, respectively. DHA can decrease the consumption of chemicals and energy. The suggested DHA method is feasible for industrial applications.
Pengfei Li - One of the best experts on this subject based on the ideXlab platform.
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site occupancy preference enhancement mechanism and thermal resistance of mn4 red luminescence in sr4al14o25 mn4 for warm wleds
Chemistry of Materials, 2015Co-Authors: Mingying Peng, Peter A Tanner, M G Brik, Pengfei LiAbstract:Red Phosphors play an indispensable role in Phosphor-based warm white light-emitting diodes (WLEDs). We demonstrated recently that the non-Rare-Earth Phosphor Sr4Al14O25:Mn4+ exhibits red luminescence even more intensely than the commercial Mn4+ Phosphor 3.5MgO.0.5MgF2.GeO2:Mn4+ upon blue excitation. Herein, on the basis of crystal field calculations employing the exchange charge model, we identify the energy levels of three types of Mn4+ ions situated at Al3+ sites in the Sr4Al14O25 crystal lattice and find that the doped manganese ions occupy preferentially the Al4 and Al5 more covalent sites rather than the Al6 site. We report that the Mn4+ luminescence can be enhanced upon the inclusion of Mg2+ in the synthesis reaction. The mechanisms for this effect comprise the lower nonradiative decay rate from the 2Eg state because of the reduction in energy migration along Mn4+ ions to killer sites and the morphology evolution from orderly layered smooth nanosheets to irregular nanoparticles disorderly compacted...
Rui M Almeida - One of the best experts on this subject based on the ideXlab platform.
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Photoluminescence from a Tb-doped photonic crystal microcavity for white light generation
Journal of Physics D: Applied Physics, 2010Co-Authors: Rui M AlmeidaAbstract:Terbium-doped one-dimensional triple microcavities have been prepared by sol-gel processing. The photoluminescence (PL) of Tb 3+ ions outside a microcavity structure, when excited by blue laser light at 488 nm, consisted of three distinct peaks at 542 nm, 587 nm and 619 nm. When embedded in the microcavities, the three Tb 3+ PL peaks were enhanced, balanced and broadened by the photonic crystal structure and combined into a continuous broad band. An analysis in the CIE colour space showed that white light can be obtained by mixing the modified Tb 3+ PL with the blue exciting light, while this is impossible with the original PL profile. This novel technique may improve white light generation by enhancing and modifying the spontaneous emission of current Phosphors. It may also lead to the development of new Rare Earth Phosphor materials based on 4f-4f transitions, able to generate white light more efficiently, via simpler and cheaper alternatives to the current Phosphor compositions. A novel configuration to combine this kind of structure with a white light-emitting-diode (LED) is also proposed.
S. Sankararaman - One of the best experts on this subject based on the ideXlab platform.
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From Futile to Fruitful: Diesel Soot as White Light Emitter
Journal of Fluorescence, 2018Co-Authors: M. S. Swapna, S. SankararamanAbstract:The present work describes a solution for the effective use of the hazardous particulate matter (diesel soot) from the internal combustion engines (ICEs) as a potential material emitting white light for white light emitting diodes (WLEDs). The washed soot samples are subjected to Field Emission Scanning Electron Microscopy (FESEM), High- Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive Spectroscopy (EDS), UV–Visible, Photoluminescent (PL) Spectroscopy and quantum yield measurements. The CIE plot and Correlated Color Temperature (CCT) reveals the white fluorescence on photoexcitation. The sample on ultraviolet (UV) laser excitation, provides a visual confirmation of white light emission from the sample. The diesel soot collected from public transport buses of different years of manufacture invariably exhibit white fluorescence at an excitation of 350 nm. The sample show a quantum yield of 47.09%. The study is significant in the context of pollution and search for low-cost, Rare-Earth Phosphor free material for white light emission and thereby turning the hazardous, futile material into a fruitful material that can be used for potential applications in photonics and electronics.
