检索结果-南通市图书馆

Optical grade (Gd_(0.95-x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) ceramics with near-zero optical loss: Effects of Lu^(3+) doping on structural feature, microstructure evolution, and far-red luminescence

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2024年第1期13卷 113-123页

作者： Zhigang Sun Ji-Guang Li Huiyu Qian Yoshio Sakka Tohru SSuzuki Bin Lu School of Materials Science and Chemical Engineering Ningbo UniversityNingbo 315211China Research Center for Electronic and Optical Materials National Institute for Materials ScienceIbaraki 305-0044Japan Key Laboratory of Photoelectric Detection Materials and Devices of Zhejiang Province Ningbo 315211China

A chemical co-precipitation strategy was employed to synthesize a series of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12)(x=0.1−0.95)powder phosphors,followed by vacuum sintering to achieve transparent garnet ceramic phosphors.The density functional theory indicated Lu_(3)Al_(5)O_(12) was formed in priority compared with Gd_(3)Al_(5)O_(12) during solid-phase reaction.Upon high-temperature sintering,the Lu^(3+)substitution for Gd^(3+)suppressed point mass diffusion leading to a smaller grain size.The in-line transmittances of bulk specimens with x=0.1,0.3,0.5,0.7,and 0.95 nm were~83.5%,80.1%,68.8%,73.7%,and 82.2%at 710 nm(Eu^(3+)emission center),respectively,among which the sample of x=0.1 exhibited the optical grade with near-zero optical loss in agreement with the defect-free single crystal(~100%of the theoretical transmittance).The resulting particle and ceramic materials both presented characteristic Eu^(3+)emission arising from 5D0→7FJ(J=1−4)transition,where the dominant far-red emission at~710 nm arising from ^(5)D_(0)→^(7)F_(4) transition overlapped with the absorption of phytochrome(PFR).The photoluminescence excitation and photoluminescence intensities of(Gd_(0.95−x)Lu_(x)Eu_(0.05))_(3)Al_(5)O_(12) powders and ceramics generally increased at a higher Gd^(3+)/Lu^(3+)ratio.Lu^(3+)dopants delayed the fluorescence lifetime while the bulk samples had shorter lifetime compared to the particle counterparts.The transparent(Gd_(0.85)Lu_(0.1)Eu_(0.05))3Al_(5)O_(12) ceramic phosphor exhibited good thermal stability with a high thermal quenching temperature above 533 K.The designed ceramic phosphor-converted light-emitting diode had a saturation injection current of 435 mA and a current-dependent color rendering index.More importantly,our report marked the developmental stage of transparent ceramic materials towards zero optical loss.

关键词： transparent ceramics garnet phosphors light-emitting diode(LED) optical properties Gibbs free energy

Rare-earth and transition metal ion single-/co-doped double-perovskite tantalate phosphors: Validation of suitability for versatile applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2023年第5期12卷 954-971页

作者： Yongbin Hua Jae Su Yu Li Li Department of Electronics and Information Convergence Engineering Institute for Wearable Convergence ElectronicsKyung Hee UniversityYongin-si 17104Republic of Korea School of Science Chongqing University of Posts and TelecommunicationsChongqing 400065China

Novel rare-earth (RE;e.g., europium (Eu^(3+)), samarium (Sm^(3+)), and praseodymium (Pr^(3+))) and transition metal (TM^(4+);e.g., manganese (Mn^(4+))) ion single-/co-doped double-perovskite Ca2InTaO6 (CITO) phosphors were prepared and investigated with respect to their crystal structure and photoluminescence (PL) properties. Among them, the CITO:Eu^(3+) phosphors were found to exhibit an ultra-high internal PL quantum yield (89.1%) and good thermal stability (78.7% at 423 K relative to the initial value at 303 K). As such, the corresponding packaged white light-emitting diode (LED) was able to display a remarkable color rendering index (CRI;= 91.51@10 mA). Besides, the potential in applications of anti-counterfeiting fields and a novel LED structure based on flexible phosphor-converted films was also studied. Moreover, due to their different thermal quenching, trivalent lanthanide (Ln^(3+))/Mn^(4+) co-doped CITO phosphors were designed for optical thermometry based on the luminescence intensity ratio (LIR) between different 4f transitions of various Ln^(3+) ions and ^(2)Eg → ^(4)A_(2g) (Mn^(4+)) transition. Particularly, the LIR between the ^(4)G_(5/2) → ^(6)H_(9/2) and ^(2)Eg → ^(4)A_(2g) peaks of the CITO activated with 5 mol% Sm^(3+) and 0.3 mol% Mn^(4+) exhibited the most excellent relative sensitivity (Sr;= 3.80 %·K^(−1)) with beneficial temperature uncertainty of 0.0648 K. Overall, these results are of significance to offer valuable databases for constructing multifunctional high-performance optical platforms using single-/co-doped double-perovskite tantalates.

关键词： phosphors quantum yields(QYs) light-emitting diodes(LEDs) thermometry anti-counterfeiting

Efficient,high-CRI white LEDs by combining traditional phosphors with cadmium-free InP/ZnSe red quantum dots

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2022年第1期10卷 155-165页

作者： BEGA KARADZA HANNES VAN AVERMAET LEILA MINGABUDINOVA ZEGER HENS YOURI MEURET KU Leuven Department of Electrical Engineering(ESAT)Light&Lighting LaboratoryGebroeders De Smetstraat 19000 GentBelgium Physics and Chemistry of Nanostructures and Center for Nano and Biophotonics Krijgslaan 281-S39000 GentBelgium

Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narrowband QDs.However,the red QDs in these studies were cadmium-based,which is a restricted element in the EU and certain other countries.The use of InP-based QDs,the most promising Cd-free alternative,is often presented as an inferior solution because of the broader linewidth of these QDs.However,while narrow emission lines are the key to display applications that require a large color gamut,the spectral efficiency penalty of this broader emission is limited for lighting applications.Here,we report efficient,high-CRI white LEDs with an on-chip color converter coating based on red InP/ZnSe QDs and traditional green/yellow powder phosphors.Using InP/ZnSe QDs with a quantum yield of nearly 80% and a full width at half-maximum of 45 nm,we demonstrate high spectral efficiency for white LEDs with very high CRI values.One of the best experimental results in terms of both luminous efficacy and color rendering performance is a white LED with an efficacy of 132 lm/W,and color rendering indices of R_(a)≈90,R9 ≈50 for CCT ≈4000 K.These experimental results are critically compared with theoretical benchmark values for white LEDs with on-chip downconversion from both phosphors and red Cd-based QDs.The various loss mechanisms in the investigated white LEDs are quantified with an accurate simulation model,and the main impediments to an even higher efficacy are identified as the blue LED wall-plug Quantum dots(QDs) offer an interesting alternative for traditional phosphors in on-chip light-emitting diode(LED) configurations.Earlier studies showed that the spectral efficiency of white LEDs with high color rendering index(CRI) values could be considerably improved by replacing red-emitting nitride phosphors with narr

关键词： phosphors white rendering

Energy transfer and luminescent properties of Tb^(3+)and Tb^(3+),Yb^(3+)doped CNGG phosphors

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第9期40卷 1445-1453,I0004页

作者： S.Hau G.Stanciu D.Avram L.Gheorghe C.Gheorghe National Institute for Laser Plasma and Radiation PhysicsSolid State Quantum Electronics Laboratory409 Atomistilor StreetP.O.Box MG-36Magurele077125IlfovRomania

In this work,calcium niobium gallium garnet(Ca_(3)Nb_(1.6875)Ga_(3.1875)O_(12)-CNGG)ceramic samples singledoped with Tb^(3+)and co-doped with Tb^(3+)and Yb^(3+)ions were sintered by the solid-state reaction method.The structural characterization of the samples was carried out by X-ray diffraction measurements.The optimal concentration of Tb^(3+)ions corresponding to the maximum luminescence in the green spectral range in CNGG:x at%Tb(x=0.1,0.5,1,2,3,4,and 5)was determined to be 4 at%.The timeresolved luminescence of the^(5)D_(4)level(Tb^(3+))in the CNGG:x at%Tb samples was analysed to explore the quenching mechanisms involved in the Tb^(3+)green emission.Co-doped CNGG:4 at%Tb,y at%Yb(y=0.5,2,4,6,8,and 10)ceramics were prepared and investigated.It is shown that CNGG:4 at%Tb,y at%Yb phosphors exhibit intense green luminescence under ultra-violet(UV),visible(VIS),and near-infrared(NIR)excitation,thus demonstrating the presence of simultaneous down-conversion(DC)and upconversion(UC)processes.The dependence of the UC luminescence intensity on the diode laser pumping power was measured and the results indicate a two-photon process based on cooperative energy transfer(CET).Under UV excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level slowly increases with increase of Yb^(3+)concentration,suggesting the energy transfer from Yb^(3+)to Tb^(3+)ions,while under NIR excitation,the lifetime of the^(5)D_(4)(Tb^(3+))level decreases with increase of Yb^(3+)ions concentration,indicating the presence of a strong energy transfer from Tb^(3+)to Yb^(3+)ions.The highest energy transfer efficiency ofη_(ET)≈42%was determined for the CNGG:4 at%Tb,10 at%Yb sample.The obtained results indicate that CNGG:(Tb^(3+),Yb^(3+))could be efficient new yellowish-green-emitting phosphors.

关键词： phosphors Tb^(3+)and Tb^(3+)-Yb^(3+)luminescence properties Up-conversion Down-conversion Quantum cutting process Rare earths

Synthesis,crystal structure and photoluminescence properties of novel double perovskite La2CaSnO6:Eu3+red-emitting phosphors

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第11期40卷 1682-1690,I0001页

作者： Yangyi Xu Guifang Li Xufeng Guan Yunge Wei Maolin Zhang School of Advanced Materials and Nano Technology Xidian UniversityXi'an710071China

A series of new double perovskite LaEuCaSnO(0≤x≤0.8)red phosphors were synthesized by traditional solid-state reaction.The phase,micro structure,photoluminescence(PL)properties,quantum efficiency,and thermal stability of the phosphors were investigated.LaCaSnOmatrix has a monoclinic double perovskite structure with space group P2/n.Under near-ultraviolet(UV)light at395 nm,LaEuCaSnOphosphors exhibit the most typical red emission peak at 614 nm,which corresponds to~5 D→~7 Felectric dipole transition of Eu.The optimum Eudoping content is attained at x=0.5,and the LaEuCaSnOphosphor shows a moderate quantum efficiency(32.3%)and high color purity(92.2%).Besides,the temperature-dependent spectrum of the phosphor was studied.The emission intensity of Euat 423 K decreases to 70.94%of the initial intensity at 303 K,and the activation energyΔE is estimated to be 0.232 eV,suggesting that the phosphors possess good thermal stability.The fabricated w-LED based on the phosphors has higher Ra(89),lower CCT(4539 K),and better chromaticity coo rdinates(0.371,0.428).These results prove that the Eu-doped LaCaSnOred phosphor has great potential applications in w-LEDs.

关键词： phosphors Double perovskite Luminescence properties La2CaSnO6 Rare earths

Strategies to approach high performance in Cr^(3+)-doped phosphors for high-power NIR-LED light sources

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2020年第1期9卷 1190-1198页

作者： Zhenwei Jia Chenxu Yuan Yongfu Liu Xiao-Jun Wang Peng Sun Lei Wang Haochuan Jiang Jun Jiang Ningbo Institute of Materials Technology&Engineering Chinese Academy of SciencesNingbo 315201China College of Physics and Optoelectronics Taiyuan University of TechnologyTaiyuan 030024China University of Chinese Academy of Sciences Beijing 100049China Department of Physics Georgia Southern UniversityStateboreGA 30460USA

Broadband near-infrared(NIR)-emitting phosphors are key for next-generation smart NIR light sources based on blue LEDs.To achieve excellent NIR phosphors,we propose a strategy of enhancing the crystallinity,modifying the micromorphology,and maintaining the valence state of Cr^(3+) in Ca_(3)Sc_(2)Si_(3)O_(12) garnet(CSSG).By adding fluxes and sintering in a reducing atmosphere,the internal quantum efficiency(IQE)is greatly enhanced to 92.3%.The optimized CSSG:6% Cr^(3+) exhibits excellent thermal stability.At 150℃,97.4% of the NIR emission at room temperature can be maintained.The fabricated NIR-LED device emits a high optical power of 109.9mW at 520 mA.The performances of both the achieved phosphor and the NIR-LED are almost the best results until now.The mechanism for the optimization is investigated.An application of the NIR-LED light source is demonstrated.

关键词： phosphors power light

Ethanol-derived white emissive carbon dots:The formation process investigation and multi-color/white LEDs preparation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2022年第2期15卷 942-949页

作者： Boyang Wang Haoqiang Song Zhiyong Tang Bai Yang Siyu Lu Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450001China CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanoscienceNational Center for Nanoscience and TechnologyBeijing 100190China State Key Lab of Supramolecular Structure and Materials College of ChemistryJilin UniversityChangchun 130012China

Carbon dots(CDs)have attracted much attention due to their excellent photoelectric properties and potential applications.Although previous studies have shown that almost all organic molecules can be converted into CDs via chemical carbonization,the mechanism of the conversion process remains unclear.The hydrothermal/solvothermal method commonly used to prepare CDs is complicated and leads to the generation of many by-product CDs with similar structures.Considering that the purification of the synthesized by-products is difficult,the process of CDs formation cannot be readily analyzed and understood.Herein,we use ethanol as a carbon source to synthesize white-emitting CDs(W-CDs).Column chromatography separation shows that the synthesized W-CDs are composed of blue-,cyan-,and yellow-emitting CDs that fluoresce at wavelengths corresponding to the three emission centers of W-CDs.Although the samples have similar graphitic structure,they exhibit different surface states due to variations in the degree of oxidation and carbonization.Therefore,the red-shift in their emission peaks is attributed to an increased degree of carbonization in their polymer structure.Theoretical calculations verify the experimental results,and the prepared CDs are successfully used to develop multi-color and white light-emitting diodes(LEDs).

关键词： carbon dots multi-color-emissive cross-linking fluorescence mechanism phosphors

Tunable Emission and Energy Transfer of the Novel KY_(1-x)(MoO_(4))_(2-y)(WO_(4))y:xLn^(3+)(Ln^(3+)=Dy^(3+),Eu^(3+),and Tm^(3+))Single-phase White Luminescence Phosphor for White LEDs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1278-1286页

作者： ZHU Hai HE Bin HUANG Weigang Department of Oncology The Third People's Hospital of ChengduAfiliated Hospital of Southwest Jiaotong University&The Second Affiliated Hospital of ChengduChongqing Medical UniversityChengdu 610031China Medical Research Center The Third People's Hospital of ChengduAfiliated Hospital of Southwest Jiaotong University&The Second Afiliated Hospital of ChengduChongqing Medical UniversityChengdu 610031China National Engineering Research Center for Biomaterials College of Biomedical MaterialsSichuan UniversityChengdu 610064China College of Materials Science and Engineering Sichuan UniversityChengd 610064China

The phosphors of KY_(1-x)(MoO_(4))_(2-y)(WO_(4))y:xLn^(3+)(Ln^(3+)=Tm^(3+),Dy^(3+),Eu^(3+))were synthesized by using a sol-gel method.Then,the crystal structure,luminescence properties,energy transfer,and white emission of the prepared materials were researched.The molar ratio of the anion group on the photoluminescence(PL)emission and excitation intensity were investigated,revealing that the optimum intensity could be obtained by using=3:1.The optimal Dy^(3+) doping concentration of KY(MoO_(4))1.5(WO4)0.5was obtained.In addition,the color-tunable emissions of Dy^(3+)/Eu^(3+)-codoped KY(MoO_(4))1.5(WO4)0.5phosphors were observed because of the effective energy transfer(ET)from Dy^(3+)to Eu^(3+)ions.Finally,by doping appropriate concentrations of Tm^(3+),Dy^(3+),and Eu^(3+)and different concentrations of(WO_(4))^(2-),white light emitting phosphors KY_(0.92)(WO_(4))2:0.01Tm^(3+),0.06Dy^(3+),0.01Eu^(3+)with excellent color-rending properties were obtained.The chromaticity coordinate was calculated as(x=0.3238,y=0.3173),closing to the artificial daylight(D65,x=0.313,y=0.329)illuminant,and which indicates the potential application of near ultraviolet White light-emitting diodes(WLEDs).

关键词： rare earth phosphors white LEDs energy transfer sol-gel method

Spectral change and far-red emission of Mn^(2+)ions co-doped NaSrB_(5)O_(9):Dy^(3+)luminescence material for plant growth LEDs

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2022年第2期40卷 218-225,I0002页

作者： K.Munirathnam Koduru Mallikarjuna R.Vijaya P.C.Nagajyothi K.Ramakrishna Reddy M.Srinivas Department of Physics School of Applied SciencesREVA UniversityBengaluru560064India Department for Management of Science and Technology Development Ton Due Thang UniversityHo Chi Minh CityVietnam Faculty of Applied Sciences Ton Due Thang UniversityHo Chi Minh CityVietnam Department of Physics Visvodaya Government Degree CollegeVenkatagiri524132India School of Mechanical Engineering Yeungnam UniversityGyeongsan33541South Korea Department of Chemistry School of Applied SciencesREVA UniversityBengaluru560064India

Due to the characteristic emission of phosphors,phosphor-converted LEDs have been employed to provide the requisite light sources for indoor plant growth in the optical agricultural industry.Herein,we prepared a series of Mn^(2+)co-doped NaSrB5 O9:Dy^(3+)phosphors via a solid-state reaction method.These phosphors have significant three-band emissions at 467 nm(blue region),606 nm(orange region),and765 nm(far-red region),ascribed to the^(4)F_(9/2)-^(6)H_(15/2)and 4 F9/2-6 H13/2 transitions of the Dy^(3+)ions and the^(4)T_(1g)(G)-^(6)A_(1g)(S)spin-forbidden transition of the Mn^(2+)ions,respectively,when excited by light of 376 nm(near-UV region).The co-dopant in the host material facilitates tunable photoluminescence(PL)due to energy transfer from the Dy^(3+)ions to the Mn^(2+)ions.The three emission peaks from the prepared phosphors well match with the absorption spectra of the photosynthesis pigments of plants,chlorophyll and phytochrome,which can absorb blue(400-500 nm),orange-red(550-700 nm),and infrared(IR)radiation,indicating that these phosphors have potential applications in the fabrication of plant-growth LEDs.Prior to the PL studies,the structure of the phosphors was determined by X-ray diffraction,refined by Rietveld method and chemically quantified by X-ray photoelectron spectroscopy.

关键词： phosphors Refinement X-ray photoelectron spectroscopy Energy transfer Plant growth LEDs Rare earths