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Effect of different catalysts and growth temperature on the photoluminescence properties of zinc silicate nanostructures grown via vapor-liquid-solid method

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Chinese Physics B 2022年第5期31卷 657-665页

作者： Ghfoor Muhammad Imran Murtaza Rehan Abid Naeem Ahmad Department of Physics International Islamic UniversityIslamabad 44000Pakistan

We explore the photoluminescence properties of zinc silicate(Zn_(2)SiO_(4)) nanostructures synthesized by vapor-liquidsolid(VLS)mode of growth using three different catalysts(Sn,Ag,and Mn).Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures.Zn_(2)SiO_(4) has a wide bandgap of about 5.5 eV and in its pure form,it does not emit in visible region due to its inner shell electronic transitions between the 3 d5 energy levels.However,the incorporation of different catalysts(Sn,Ag and Mn)at different growth temperatures into the Zn_(2)SiO_(4) crystal growth kinetics provides wide visible spectral range of photoluminescence(PL)emissions.PL analysis shows broad multi-band spectrum in the visible region and distinct colors(red,yellow,green,blue,cyan and violet)are obtained depending on the crystalline structure of the prepared nanostructures.The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence.The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail.The synthesized photoluminescent nanostructures have potential applications in solidstate lighting and display devices.

关键词： nanostructures vapor-liquid-solid growth mode photoluminescence spectra fluorescence microscopy

Effect of red emitting fluorescent pigment on fluorescent color of SrAl2O4：Eu2＋,Dy3＋ phosphors

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Journal of Rare Earths 2017年第3期35卷 247-253页

作者：陈志朱亚楠葛明桥 Key Laboratory of Eco-textiles of'Ministry of Education Jiangnan University Wuxi 214122 China

Green-blue fluorescence emitting SrAl_2O_4：Eu^（2＋）,Dy^（3＋） phosphors（SAOED） were coated by SiO_2 and a coumarin type red-emitting fluorescent pigment（FP）.The effects of the FP on the morphology,crystal structure,photoluminescence properties and fluorescent color of the SAOED phosphors were systematically investigated by scanning electron microscopy（SEM）,FT-IR,X-ray diffraction（XRD）,photoluminescence spectra and CIE-1931 chromaticity coordinates characterization.Even though the surface of the SAOED phosphors became rough after being coated with SiO_2 and FP,crystal lattice of SrAl_2O_4 did not have any obvious lattice distortions.The photoluminescence spectra indicated that the SAOED phosphors could be used as the excitation light source to excite the FP to emit red fluorescence.The emission spectrum of the FP-coated SAOED consisted of a broad band with two emission peaks at 520 and 610 nm,and its fluorescence emission color was a mixed color of the SAOED phosphors and FP.The fluorescence color of the SAOED/SiO_2/FP composites tended to transfer to red area with the increase of the FP content varying from 0.1%to 0.9%.

关键词： fluorescence color fluorescent pigment coating photoluminescence spectra rare earths

Photoanode Activity of ZnO Nanotube Based Dye-Sensitized Solar Cells

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Journal of Materials Science & Technology 2011年第11期27卷 961-966页

作者： R. Ranjusha P. Lekha K.R.V. Subramanian V. Nair Shantikumar A. Balakrishnan Nano Solar Division Amrita Center for Nanosciences

Vertical ZnO nanotube （ZNT） arrays were synthesized onto an indium doped tin oxide （ITO） glass substrate by a simple electrochemical deposition technique followed by a selective etching process. Scanning electron microscopy （SEM） showed formation of well-faceted hexagonal ZNT arrays spreading uniformly over a large area. X-ray diffraction （XRD） of ZNT layer showed substantially higher intensity for the （0002） diffraction peak, indicating that the ZnO crystallites were well aligned with their c-axis. Profilometer measurements of the ZNT layer showed an average thickness of -7 μm. Diameter size distribution （DSD） analysis showed that ZNTs exhibited a narrow diameter size distribution in the range of 65-120 nm and centered at -75 nm. The photoluminescence （PL） spectrum measurement showed violet and blue luminescence peaks that were centered at 410 and 480 nm, respectively, indicating the presence of internal defects. Ultra-violet （UV） spectroscopy showed major absorbance peak at ,-348 nm, exhibiting an increase in energy gap value of 3.4 eV. By employing the formed ZNTs as the photo-anode for a dye-sensitized solar cell （DSSC）, a full-sun conversion efficiency of 1.01% was achieved with a fill factor of 54%. Quantum efficiency studies showed the maximum of incident photon-to-electron conversion efficiency in a visible region located at 590-550 nm range.

关键词： ZnO nanotubes Indium doped tin oxide （ITO） glass photoluminescence spectra Electrochemical deposition Quantum efficiency

A New Yellow Long Lasting Phosphor Y_2O_2S∶Ti

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Journal of Rare Earths 2004年第1期22卷 63-66页

作者：张朋越王民权洪樟连樊先平钱国栋王智宇 Department of Materials Science and Engineering

A new kind of doped rare earth free phosphor Y 2O 2S∶xTi (0 详细信息

A new kind of doped rare earth free phosphor Y 2O 2S∶xTi (0photoluminescence spectra, time-resolved phosphorescence spectra and decay curves of the phosphor were investigated. XRD results reveal that a single Y 2O 2S phase exists with Ti content up to 6% (mol fraction). Yellow long lasting phosphorescence for present materials was observed in the dark with naked eye after the removal of the excitation light. From the time-resolved phosphorescence spectra the broad emission band centered at 565 nm was confirmed to be responsible for the long lasting phosphorescence which could maintain above 1 h. The possible mechanism responsible for the long lasting phosphorescence of the Y 2O 2S∶Ti phosphor was proposed.

关键词： optics Y 2O 2S∶Ti photoluminescence spectra time-resolved phosphorescence spectra decay curves rare earths

Fabrication and photoluminescence characteristics of nonuniform Yb-Er codoped films

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Journal of Rare Earths 2008年第1期26卷 31-34页

作者：李成仁雷明凯李淑凤刘玉凤宋昌烈 School of Materials Science and Engineering Dalian University of Technology School of Materials Science and Engineering Dalian University of Technology School of Physics and Optoelectronic Technology Dalian University of Technology College of Physics and Electronic Technology Liaoning Normal University

The nonuniform Yb-Er Codoped Al2O3 films were prepared on SiO2/Si substrates using a medium frequency magnetron sputtering system. Two asymmetry targets in the system were introduced to realize the nonuniform dopant. Some curves of photoluminescence （PL） peak intensity were obtained by adjusting the deposition parameters, such as, the pillar number of erbium and ytterbium in the mixed target and the distance between a sample table and targets. Typically, the curve of PL peak intensity against the offset distance was approximately linear. The ratio of the PL intensity at the two ends of the same sample was 12.6 and the slope was 71.83/mm when the pillar numbers of the erbium and ytterbium in the mixed target are 5 and 60, respectively, and the distance between targets and the sample table is 2.9 cm.

关键词： Yb-Er codoped nonuniform films the medium frequency magnetron sputtering system asymmetry targets photoluminescence spectra rare earths

Fabrication of titania thin film with composite nanostructure and its ability to photodegrade rhodamine B in water

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Frontiers of Chemical Science and Engineering 2008年第1期2卷 44-48页

作者： Gaojie ZHANG Jinming WU Shaoguang LIU Mi YAN Department of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China State Key Lab of Silicon Materials Zhejiang UniversityHangzhou 310027China

A titania nanorod filmwas synthesized by direct oxidation of metallic Ti with hydrogen peroxide solution under a low temperature.Titania nanoparticles were then filled into the gaps among the nanorods through an infiltration sol-gel procedure to form a composite titania film with an ordered nanostructure.X-ray diffraction spectra indicate that the composite film was a mixture of anatase and rutile while the titania film obtained by only using a sol-gel procedure was pure anatase.Field emission scanning electron microscopy observations show that titania nanoparticles were embedded into the titania nanorod film.photoluminescence spectra suggest the enhanced separation of electron and hole pairs for the obtained composite titania film over the corresponding titania nanorod film.The composite titania film exhibited improved ability to photodegrade rhodamine B in water compared with the titania nanorod film.The apparent photodegradation rate constant,fitting a pseudo-first-order,was 3 times of that obtained by the sol-gel derived titania film at the same weight.The improved photocata-lytic activity for the composite titania film could be attributed to the enhanced separation of electron and hole pairs due to the embedding of the titania nanoparticles within the titania nanorods.

关键词： titania composite catalyst film sol-gel nanorod photoluminescence spectra

The influence of nickel dopant on the microstructure and optical properties of SnO2 nano-powders

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Chinese Physics B 2007年第1期16卷 95-99页

作者：刘春明方丽梅祖小涛周伟列 Department of Applied Physics University of Electronic Science and Technology of China Chengdu 610054 China International Center for Material Physics Chinese Academy of Sciences Shenyang 110015 China Advanced Materials Research Institute University of New Orleans New Orleans LA 70148 USA

The microstructure and optical properties of Ni-doped SnO2 nano-powders are studied in detail. By Ni-doping, not only the grain size reduces, but also the grain shape changes from nano-rods to spherical particles. The crystallization becomes better with annealing temperature increasing. The band gap energy decreases as nickel doping level increases. The sp-d hybridization and alloying effect due to amorphous SnO2-x phase should be responsible for the band gap narrowing effect. Nickel dopant does not change the photoluminescence （PL） peak positions.

关键词： microstructure optical absorption spectra photoluminescence spectra SnO2

Optics Characteristic Research of ZnO Nanowire Arrays Preparedby Porous Anodic Aluminum Oxide Template

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Optics Characteristic Research of ZnO Nanowire Arrays Prepar...