scholarly journals Solvent-Mediated Structural Evolution Mechanism from Cs4PbBr6 to CsPbBr3 Crystals

2021 ◽  
Vol 1 (2) ◽  
pp. 67-74
Author(s):  
Felipe A. La Porta ◽  
Sofia Masi
Keyword(s):  
Uv Light ◽  
Structural Evolution ◽  
Green Emission ◽  
Solvent Polarity ◽  
Rhombohedral Structure ◽  
Defect States ◽  
Evolution Mechanism ◽  
Emission Color ◽  
Composition Structure ◽  
Surface Decomposition

The study of the solvent-mediated structural evolution mechanism of the Cs4PbBr6 powders prepared using the solvothermal method is presented. The Cs4PbBr6 powders with a rhombohedral structure and an intense green emission (i.e., mainly due to the presence of complex defect states in the forbidden gap), which is stable in its solid-state form, but a distinct behavior is observed in different dispersions, easily detectable when irradiated with ultraviolet (UV) light. Depending on the polarity of the solvent, a change in the emission color from green to red is observed, easily detectable when irradiated with ultraviolet (UV) light. Our findings suggest that the solvent polarity affects the surface decomposition process, leading to a different change in composition, structure and crystal shape. This peculiar behavior plays a pivotal role in the control of the properties of Cs4PbBr6, and this study, therefore, offers a fundamental understanding needed for Cs4PbBr6 potential future applications.

The variety of emission color Eu2+ doped barium silicate phosphors for LEDs, Ba4Si6O16:Eu2+ and Ba5Si8O21:Eu2+

2012 ◽  
Vol 1471 ◽  
Author(s):  
T. Ishigaki ◽  
K. Sato ◽  
S. Kamei ◽  
K. Uematsu ◽  
K. Toda ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Reaction ◽  
Uv Light ◽  
Green Emission ◽  
Framework Structure ◽  
Conventional Solid State Reaction ◽  
Barium Silicate ◽  
Emission Color ◽  
A Chain ◽  
Silicate Phosphors

ABSTRACTBlue-green emitted barium silicate phosphors, Ba4Si6O16:Eu2+ and Ba5Si8O21:Eu2+, were prepared by a conventional solid-state reaction. In these hosts, the corner-sharing [SiO4] tetrahedral formed a chain framework structure. These silicate phosphors can be efficiently excited by n-UV light, yielding an intense blue-green emission. Under excitation by near UV light, the emission bands are broader than that of the Ba2SiO4:Eu2+ phosphor.

Emission Color Variation of Sr3SiO5:Ce3+, Li+ Phosphor for Near-UV Light-Emitting Diodes by Co-Doping with Mg2+ and Ba2+

2013 ◽  
Vol 690-693 ◽  
pp. 555-558 ◽  
Author(s):  
Ping Ping Zhu ◽  
Tong Wen Huang ◽  
Xiao Jun Wang ◽  
Hui Li Li ◽  
Zhuo Sun
Keyword(s):  
Thermal Stability ◽  
Uv Light ◽  
Color Variation ◽  
Spectral Variation ◽  
Solid State Method ◽  
Light Emitting ◽  
Co Doping ◽  
Yellow Color ◽  
Emission Color ◽  
Composition Structure

This paper reports the spectral variation of Sr3SiO5: Ce3+, Li+ phosphor. It was synthesized by the conventional solid state method. The effects of calcining temperature and codoption of Mg2+ and Ba2+ on phase composition, structure, photoluminescence and thermal stability were firstly investigated in detail. Under the near-UV excitation of 415 nm, Sr3SiO5: Ce3+, Li+ emits a bright greenish-yellow color centered at 532nm, which originates from 5d to 4f (2F7/2 and 2F5/2) transition of Ce3+. The PL spectra show the different emission color variation with substituting Sr2+ cations with smaller Mg2+ or larger Ba2+, which makes it be applied as a color-tunable phosphor for LED based on near-UV chip/phosphor technology. Simultaneously, the thermal stability of (Sr,Ba)3SiO5: Ce3+, Li+ phosphor is improved markedly.

Syntheses, crystal structures and photoluminescence properties of two rare-earth molybdates CsLn(MoO4)2 (Ln=Eu, Tb)

2018 ◽  
Vol 233 (2) ◽  
pp. 73-79 ◽  
Author(s):  
Dan Zhao ◽  
Fa-Xue Ma ◽  
Bao-Zhong Liu ◽  
Yun-Chang Fan ◽  
Xue-Feng Han ◽  
...  
Keyword(s):  
Rare Earth ◽  
Uv Light ◽  
Layer Structure ◽  
Green Emission ◽  
Salt Flux ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Light Excitation ◽  
Rare Earth Molybdates

AbstractSingle crystals of two cesium rare-earth molybdates CsLn(MoO4)2(Ln=Eu, Tb) have been prepared using the high temperature molten salt (flux) method. Single-crystal X-ray diffraction analyses reveal that they crystallize in the orthorhombic space groupPccm(No. 49) and features a 2D layer structure that is composed of [Ln(MoO4)2]∞and [Cs]∞layers. Under near-UV light excitation, emission spectrum of CsEu(MoO4)2consists of several sharp lines due to the characteristic electronic transitions of Eu3+ions, whereas CsTb(MoO4)2exhibits characteristic green emission of Tb3+ions.

scholarly journals Multifunctional Ionogels Incorporated with Lanthanide (Eu3+, Tb3+) Complexes Covalently Modified Multi-Walled Carbon Nanotubes

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1099 ◽  
Author(s):  
Qiuping Li
Keyword(s):  
Carbon Nanotubes ◽  
Ionic Liquids ◽  
Uv Light ◽  
Green Emission ◽  
Sem Images ◽  
Hybrid Gels ◽  
Multi Walled Carbon Nanotubes ◽  
Electric Materials ◽  
Walled Carbon Nanotubes ◽  
Functionalized Mwcnts

Ionogels refer to an emerging composite material made from the confinement of ionic liquids within some specific cross-linked network matrices. They have potential applications in areas such as electrochemical and optical-electric materials. Incorporation of lanthanide (Eu3+, Tb3+) complexes covalently functionalized multi-walled carbon nanotubes (MWCNTs) in ionogels provide new ideas to design and synthesize novel luminescent hybrid materials that have excellent characteristics of luminescence and ionic conductivity. Here, the multifunctional ionogels were synthesized by confining an ionic liquid and the rare earth functionalized MWCNTs in the cross-linked polymethyl methacrylate (PMMA) networks, resulting in a novel optical/electric multifunctional hybrid material. The SEM images and digital photographs suggest that the lanthanide functionalized MWCNTs are evenly dispersed in the hybrid matrices, thus leading to a certain transparency bulky gel. The resulting ionogels exhibit certain viscosity and flexibility, and display an intense red/green emission under UV-light irradiation. The intrinsic conductibility of the embedded ionic liquids and carbon nanotubes in conjunction with the outstanding photoluminescent properties of lanthanide complexes makes the soft hybrid gels a material with great potential and valuable application in the field of optical-electric materials.

scholarly journals Studying the structural and electronic effects of substituted (Bi0.5Na0.5)TiO3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1522-C1522
Author(s):  
Peter Blanchard ◽  
Brendan Kennedy ◽  
Chris Ling
Keyword(s):  
Solid Solutions ◽  
Structural Changes ◽  
Structural Evolution ◽  
Rhombohedral Phase ◽  
Rhombohedral Structure ◽  
Electronic Effects ◽  
Spectra Analysis ◽  
Space Group ◽  
Industry Standard ◽  
Made In

Significant efforts have been made in the development of (Bi0.5Na0.5)TiO3 ferroelectrics as an alternative to the lead-based industry standard PbTi1-xZrxO3.[1] It has also been shown that doping the A- and B-site of (Bi0.5Na0.5)TiO3 can greatly improve the ferroelectric behavior of these materials,[2] possibly due to the formation of two or more ferroelectric phases at a morphotropic phase boundary (MPB). As such, there is a significant interest in understanding the structural changes in (Bi0.5Na0.5)TiO3-based solid solutions. (Bi0.5Na0.5)TiO3 was originally described as adopting a rhombohedral structure in space group R3c, However, the accuracy of this description has been greatly debated. It was recently suggested that (Bi0.5Na0.5)TiO3 actually adopts a monoclinic structure in space group Cc.[3] Given this recent controversy, we investigated the structural evolution of (Bi0.5Na0.5)TiO3-based solid solutions, particularly the (Bi0.5Na0.5)Ti1-xZrxO3 and (1-x)(Bi0.5Na0.5)TiO3–xBiFeO3 solid solutions., using both diffraction and spectroscopy techniques. Diffraction measurements on (Bi0.5Na0.5)TiO3 confirm that both monoclinic Cc and rhombohedral R3c phases are present at room temperature. Diffraction analysis showed that doping (Bi0.5Na0.5)TiO3 with a small amount of (Bi0.5Na0.5)ZrO3 and BiFeO3 can stabilizes the rhombohedral phase. The Ti/Fe K-edge and Zr L3-edge XANES spectra analysis was performed to determine the effects doping has on the local displacement of the B-site cations.

scholarly journals Green Chemical Synthesis of N-Cholyl-L-Cysteine Encapsulated Gold Nanoclusters For Fluorometric Detection of Mercury Ions

2021 ◽  
Author(s):  
Kasthuri Jayapalan ◽  
Sivasamy Arumugam ◽  
Rajendiran Nagappan
Keyword(s):  
Uv Light ◽  
Stokes Shift ◽  
Gold Nanoclusters ◽  
Green Emission ◽  
Fluorescence Analysis ◽  
Cost Effective ◽  
Single Step ◽  
Fluorometric Detection ◽  
Transmission Electron ◽  
Green Chemical Synthesis

Abstract Here we report a simple, single-step, cost-effective, environmentally friendly, and biocompatible approach using sodium salt of N-cholyl-L-cysteine (NaCysC) capped gold nanoclusters (AuNCs) with green emission properties at above the CMC in aqueous medium under UV-light irradiation. The primary and secondary CMC of NaCysC was found to be 4.6 and 10.7 mM respectively using pyrene as fluorescent probe. The synthesized AuNCs exhibit strong emission maxima at 520 nm upon excitation of 375 nm with a large Stokes shift of 145 nm. The surface functionality and morphology of NCs are studied by Fourier transform infrared spectroscopy, dymanic light scattering studies and transmission electron microscopy. The formation of AuNCs was completed within 5 h and exhibit high stability for more than 6 months. The NaCysC templated AuNCs selectively quenches the Hg2+ ions with higher sensitivity in aqueous solution over the other metal ions. The fluorescence analysis of Hg2+ showed a wide linear range from 15 to 120 µM and a detection limit was found to be 15 nM.

scholarly journals Intrinsic Control in Defects Density for Improved ZnO Nanorod-Based UV Sensor Performance

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 142 ◽  
Author(s):  
Abu ul Hassan Sarwar Rana ◽  
Shoyebmohamad F. Shaikh ◽  
Abdullah M. Al-Enizi ◽  
Daniel Adjei Agyeman ◽  
Faizan Ghani ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Uv Light ◽  
Crystal Defects ◽  
Intrinsic Defect ◽  
Zno Nanorod ◽  
Defect States ◽  
Uv Sensor ◽  
Sensor Performance ◽  
Pair Generation ◽  
Passive Metal

Hitherto, most research has primarily focused on improving the UV sensor efficiency via surface treatments and by stimulating the ZnO nanorod (ZNR) surface Schottky barriers. However, to the best of our knowledge, no study has yet probed the intrinsic crystal defect generation and its effects on UV sensor efficiency. In this study, we undertake this task by fabricating an intrinsic defect-prone hydrothermally grown ZNRs (S1), Ga-doped ZNRs (S2), and defect-free microwave-assisted grown ZNRs (S3). The defect states were recognized by studying X-ray diffraction and photoluminescence characteristics. The large number of crystal defects in S1 and S2 had two pronged disadvantages. (1) Most of the UV light was absorbed by the defect traps and the e–h pair generation was compromised. (2) Mobility was directly affected by the carrier–carrier scattering and phonon scattering processes. Hence, the overall UV sensor efficiency was compromised based on the defect-induced mobility-response model. Considering the facts, defect-free S3 exhibited the best UV sensor performance with the highest on/off ratio, the least impulse response time, the highest recombination time, and highest gain-induced responsivity to 368 nm UV light, which was desired of an efficient passive metal oxide-based UV sensor. Our results were compared with the recently published results.

scholarly journals Synthesis, Characterization of α-Al2O3 Nanoparticles and Its Application in Decolorization of Methyl Orange Azo Dye in the Presence of UV Light

2019 ◽  
Vol 5 (1) ◽  
pp. 580-583 ◽  
Author(s):  
Vijaya P. Dhawale . ◽  
Datta J. Late . ◽  
Satish D. Kulkarni .
Keyword(s):  
Methyl Orange ◽  
Contact Time ◽  
Uv Light ◽  
Sol Gel ◽  
Water System ◽  
Rhombohedral Structure ◽  
Textile Dye ◽  
Al2o3 Nanoparticles ◽  
Uv Visible ◽  
Α Al2o3

Present study deals with the sol-gel synthesis and application of α-Al2O3 nanoparticles (alumina) to decolorize the azo anionic dye methyl orange (MO). α-Al2O3 nanoparticles were successfully synthesized using aluminium oxide, 25% ammonia and polyvinyl alcohol (PVA) were used as low cost raw materials. The properties of synthesized nanoparticles were investigated by using UV-visible spectroscopy, XRD, FTIR, SEM, EDAX, Raman spectroscopy and TEM. From UV–visible spectra, band gap was calculated and it was found to be 3.31 eV. Average crystal size of α-Al2O3 nanoparticles from XRD peaks found to be 25 nm having rhombohedral structure. FTIR spectra reveals that functional groups (O-Al-O) are present. SEM image shows distribution pattern of α-Al2O3 nanoparticles. Chemical composition of α-Al2O3 nanoparticles was confirmed from EDAX spectroscopy measurement. Raman spectra showed crystalline nature of α-Al2O3 nanoparticles. The effect of concentration and pH of dye, dosage of nano adsorbent and contact time were studied. The systematic study shows that, successful color removal of methyl orange dye up to 54% in three hours contact time of pH 4. Hence α-Al2O3 nanoparticles can be used for dye removal from waste water. Industrialization of this technique will be cost effective way to decolorize the textile dye present in water system.

scholarly journals Polyester Fabric With Fluorescent Properties Using Microwave Technology For Anti-Counterfeiting Applications

2021 ◽  
Author(s):  
Fredj Saad ◽  
Ayda Baffoun ◽  
Boris Mahltig ◽  
Mohamed Hamdaoui
Keyword(s):  
Uv Light ◽  
Ultra Violet ◽  
Green Emission ◽  
Polyester Fabric ◽  
Fluorescent Properties ◽  
Microwave Technology ◽  
Uv Absorber ◽  
Yellow Coloration ◽  
Transmission Measurements ◽  
Light Resistance

Abstract The article presented concerns the application of fluorescein as a fluorescent material for anti-counterfeiting technology which will allow the labeling and identification of legitimate articles in the textile field. Fluorescein has been applied to polyester fabrics by microwave irradiation technique in the presence of a UV absorber. Thus, its presence in the textile substrate is detectable following an excitation at a specific wavelength belonging to the Ultra-violet zone, which makes this material very effective for tracking and detecting counterfeit articles. Fluorescent samples are characterized morphologically by scanning electron microscopy (SEM) and quantitatively by optical spectroscopy such as reflectance and transmission measurements. The treated samples show under UV light a yellowish green emission with a slight yellow coloration of the polyester fiber. The UV absorber applied to the fluorescent solution improves the light resistance of the treated samples by 25%. Their addition to the bath can also ensure the production of a protective fabric against UV.

scholarly journals Energy transfer-mediated white light emission from Nile red-doped 9,10-diphenylanthracene nanoaggregates upon excitation with near UV light

2019 ◽  
Vol 18 (11) ◽  
pp. 2748-2758 ◽  
Author(s):  
Biswajit Manna ◽  
Amitabha Nandi ◽  
Rajib Ghosh
Keyword(s):  
Energy Transfer ◽  
White Light ◽  
Light Emission ◽  
Uv Light ◽  
Nile Red ◽  
Blue Emission ◽  
Green Emission ◽  
White Light Emission ◽  
Bright White Light ◽  
Red Lead

The excitonic blue emission, excimeric green emission and energy transfer-mediated red emission of Nile red lead to bright white light emission upon the photoexcitation of Nile red-doped DPA nanoaggregates.

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