SYNTHESIS OF CaWO4 AND CaWO4:Eu MICROSPHERES BY PRECIPITATION

NANO ◽  
2014 ◽  
Vol 09 (01) ◽  
pp. 1450008 ◽  
Author(s):  
YUGUO YANG ◽  
XUPING WANG ◽  
BING LIU
Keyword(s):  
Electron Microscopy ◽  
Emission Band ◽  
Large Scale ◽  
Blue Emission ◽  
Average Diameter ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
Transmission Electron ◽  
Cetyltrimethyl Ammonium

Nearly monodisperse CaWO 4 and CaWO 4: Eu 3+ microspheres have been synthesized in large scale by a surfactant-assisted solution route, in which cetyltrimethyl ammonium bromide (CTAB) is used. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) were used to characterize the resulting samples. The results of XRD indicate that the CaWO 4 and CaWO 4: Eu 3+ samples have the scheelite structures. The growth process of these nearly monodisperse spheres with an average diameter around 3.2 μm has been examined. The results of FTIR indicate that CTAB plays an important role in the formation of microspheres. The CaWO 4 microspheres exhibit a blue emission band with a maximum at 423 nm. But the CaWO 4: Eu 3+ microspheres exhibit a red emission band with a maximum at 623 nm.

Origin of blue emission in ThO2 nanorods: exploring it as a host for photoluminescence of Eu3+, Tb3+ and Dy3+

RSC Advances ◽  
2014 ◽  
Vol 4 (93) ◽  
pp. 51244-51255 ◽  
Author(s):  
Santosh K. Gupta ◽  
P. S. Ghosh ◽  
A. Arya ◽  
V. Natarajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Reverse Micelle ◽  
Cetyl Trimethyl Ammonium Bromide ◽  
Blue Emission ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Cetyl Trimethyl Ammonium

Nanorods of ThO2 were synthesized in a reverse micelle technique using cetyl trimethyl ammonium bromide as a surfactant and characterized by X-ray diffraction and transmission electron microscopy.

Study of Growth and Characterization of Fe-Catalyzed β-Ga2O3 Nanowires

2015 ◽  
Vol 1751 ◽  
Author(s):  
Sudheer Kumar ◽  
C. Tessarek ◽  
A. Hähnel ◽  
S. Christiansen ◽  
R. Singh
Keyword(s):  
Emission Band ◽  
Blue Emission ◽  
Chemical Vapor ◽  
Luminescence Properties ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Blue Emission Band ◽  
Single Crystalline ◽  
Transmission Electron ◽  
High Resolution Tem

ABSTRACTIn the present study, Fe as a catalyst was used to grow single crystalline monoclinic gallium oxide (β-Ga2O3) nanowires using chemical-vapor-deposition method. The morphology, structure and luminescence properties of the as-grown β-Ga2O3 nanowires were investigated using various characterization techniques. The diameter of the as-grown nanowires was in the range of 50 to 100 nm, and the lengths up to tens of micrometers. The structural investigation of the nanowires was carried out using X-ray diffraction that showed monoclinic phase of Ga2O3. Further, the transmission electron microscope (TEM) investigations along with selected area diffraction pattern revealing single crystalline nature of the nanowires. The as-grown β-Ga2O3 nanowires had preferred orientation along [1-1-1] direction. The high resolution TEM image showed regular arrangement of atoms and the lattice spacing between (1-1-1) planes was around 0.266 nm. The luminescence properties of the as-grown nanowires were measured using cathodoluminescence (CL) spectroscopy. The CL measurements of β-Ga2O3 nanowires revealed a strong broad UV-blue emission band and a weak red emission band.

Low Temperature Large Scale CVD Synthesis of Nano Onion-Like Fullerenes

2012 ◽  
Vol 490-495 ◽  
pp. 3211-3214 ◽  
Author(s):  
Lei Shan Chen ◽  
Cun Jing Wang
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Aluminum Hydroxide ◽  
Large Scale ◽  
Iron Catalyst ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Naoh Solution ◽  
Synthesis Reactions

Synthesis reactions were carried out by chemical vapor deposition using iron catalyst supported on aluminum hydroxide at 400 °C and 420 °C, in the presence of argon as carrier gas and acetylene as carbon source. The aluminum hydroxide support was separated by refluxing the samples in 40% NaOH solution for 2 h and 36% HCl solution for 24 h, respectively. The samples were characterized by field-emission scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy and X-ray diffraction. The results show that carbon nanotubes were the main products at 420 °C, while large scale high purity nano onion-like fullerenes encapsulating Fe3C, with almost uniform sizes ranging from 10-50 nm, were obtained at the low temperature of 400 °C.

Control of Morphology and Growth Direction of Gallium Nitride Nanostructures

2003 ◽  
Vol 789 ◽  
Author(s):  
Seung Yong Bae ◽  
Hee Won Seo ◽  
Jeunghee Park
Keyword(s):  
Electron Microscopy ◽  
Gallium Nitride ◽  
Large Scale ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Temperature Range ◽  
Transmission Electron

ABSTRACTVarious shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900–1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 – 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures.

Uniform Cerium-Based Coordination Polymer Microspheres: Preparation and Upconversion Emission

2016 ◽  
Vol 16 (4) ◽  
pp. 3705-3709 ◽  
Author(s):  
Zhi-Wen Nie ◽  
Cheng-Hui Zeng ◽  
Gang Xie ◽  
Sheng-Liang Zhong
Keyword(s):  
Electron Microscopy ◽  
Coordination Polymer ◽  
Large Scale ◽  
Upconversion Emission ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Transmission Electron ◽  
Light Excitation ◽  
Luminescent Spectra

Homogeneously doped Yb3+ and Er3+ cerium-based coordination polymer (CP) microspheres have been successfully synthesized on a large scale through a simple solvothermal route with 2, 5-pyridinedicarboxylic acid (2, 5-H2PDC) as the organic linker. CeO2:Yb3+, Er3+ porous microspheres were obtained by annealing the corresponding CP microspheres at 600 °C for 4 h under atmospheric pressure. These as-prepared products were characterized by Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersion X-ray (EDX) spectroscopy, Thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis. The room temperature upconversion luminescent spectra of the as-prepared microspheres were carried out by 980 nm NIR light excitation. Interestingly, Yb3+ and Er3+ codoped CP microspheres give a single-band emission centered at 673 nm, while the CeO2:Yb3+, Er3+ microspheres give emission in green and red region, with red being the dominant emission. The emission intensity of the CeO2:Yb3+, Er3+ microspheres were much stronger than that of the Yb3+ and Er3+ codoped CP microspheres.

SYNTHESIS OF In2O3 NANOWIRES ENHANCED BY ANODIC ALUMINA MEMBRANE

2006 ◽  
Vol 05 (04n05) ◽  
pp. 479-485
Author(s):  
C. W. LAI ◽  
X. Y. ZHANG ◽  
H. C. ONG ◽  
J. Y. DAI ◽  
H. L. W. CHAN
Keyword(s):  
Electron Microscopy ◽  
Large Scale ◽  
Anodic Alumina ◽  
X Ray Diffraction ◽  
Alumina Membrane ◽  
Thermal Evaporation Method ◽  
Single Crystalline ◽  
X Ray ◽  
Alumina Membranes ◽  
Transmission Electron

Large-scale single crystalline In 2 O 3 nanowires were successfully synthesized on anodic alumina membranes by a simple thermal evaporation method at 570°C. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy studies revealed the formation of single crystalline In 2 O 3 nanowires with diameters of 50–100 nm and lengths of up to a few hundreds of micrometers. Cathodeluminescence study revealed existence of oxygen vacancies evidenced by a strong and broad emission at 470 nm with a shoulder at 400 nm. The growth mechanism of the nanostructures is also discussed.

Synthesis and upconversion luminescence properties of CaF2:Yb3+,Er3+ nanoparticles obtained from SBA-15 template

2010 ◽  
Vol 25 (10) ◽  
pp. 2035-2041 ◽  
Author(s):  
Zhiguo Xia ◽  
Peng Du
Keyword(s):  
Electron Microscopy ◽  
Upconversion Luminescence ◽  
Emission Spectra ◽  
Average Diameter ◽  
Cubic Phase ◽  
Pumping Power ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Transmission Electron

CaF2:Yb3+,Er3+ upconversion (UC) luminescence nanoparticles have been synthesized using mesoporous silica (SBA-15) as a hard template. The samples were characterized by x-ray diffraction, Fourier transform infrared spectra, field-emission scanning electron microscopy, transmission electron microscopy, and UC emission spectra, respectively. Highly crystalline cubic phase CaF2:Yb3+,Er3+ nanoparticles are uniformly distributed with an average diameter of about 40–50 nm, and the formation process is also demonstrated. The UC fluorescence has been realized in the as-prepared CaF2:Yb3+,Er3+ nanoparticles on 980-nm excitation. The UC emission transitions for 4F9/2–4I15/2 (red), 2H11/2–4I15/2 (green), 4S3/2–4I15/2 (green), and 2H9/2–4I15/2 (violet) in the Yb3+/Er3+ codoped CaF2 nanoparticles depending on pumping power and temperature have been discussed. The UC mechanism, especially the origin on the temperature-dependent UC emission intensities ratio between 2H11/2 and 4S3/2 levels, have been proposed.

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ Particles: Polyol-Mediated Synthesis and Luminescent Properties

2007 ◽  
Vol 7 (2) ◽  
pp. 602-609 ◽  
Author(s):  
Zhenling Wang ◽  
Guangzhi Li ◽  
Zewei Quan ◽  
Deyan Kong ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Blue Emission ◽  
Luminescent Properties ◽  
Spherical Particles ◽  
Sem Images ◽  
Blue Emission Band ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
20 Nm

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Pb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodoluminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10–20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4–7FJ (J = 6 – 3) transitions due to an energy transfer from WO42− groups to Pb3+.

Synthesis and Characterization of γ-Al2O3 Nanowires by a Surfactant Assisted Precipitation Method

2014 ◽  
Vol 602-603 ◽  
pp. 93-96 ◽  
Author(s):  
Fan Cheng Meng ◽  
Cheng Liu ◽  
Xiao Lei Zhang ◽  
Hai Shen Ren ◽  
Tie Kun Jia
Keyword(s):  
Raw Materials ◽  
Sodium Aluminate ◽  
Precipitation Method ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
Ctab Concentration ◽  
Transmission Electron ◽  
Cetyltrimethyl Ammonium ◽  
Surfactant Assisted

In this study, the γ-Al2O3 nanowires were prepared by a simple surfactant assisted precipitation method using the cetyltrimethyl ammonium bromide (CTAB) as a structure-directing agent (SDAs). Homemade sodium aluminate (NaAlO2) and H2O2 were used as raw materials. The influences of CTAB concentration and calcination temperature on the morphology of product were discussed. The obtained samples were investigated using transmission electron microscopy, X-ray diffraction analysis and TG-DSC. In the end, a possible formation mechanism of wire-like γ-Al2O3 is proposed.

An environmentally friendly method for the isolation of cellulose nano fibrils from banana rachis fibers

2016 ◽  
Vol 87 (1) ◽  
pp. 81-90 ◽  
Author(s):  
Vincent Mukwaya ◽  
Weidong Yu ◽  
Rabie AM Asad ◽  
Hajo Yagoub
Keyword(s):  
Electron Microscopy ◽  
Average Diameter ◽  
Enzyme Hydrolysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sonic Treatment ◽  
Xrd Studies ◽  
Environmentally Friendly Method ◽  
Derivative Thermogravimetry

Cellulose nano fibrils (CNFs) were isolated from banana rachis bran using enzyme hydrolysis with subsequent ultra-sonic treatment. The CNFs and bran were characterized by particle size distribution (only the CNFs), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy; the morphology of the banana rachis fiber and CNFs was observed using scanning electron microscopy and transmission electron microscopy, respectively. The furnished nano fibrils had an average diameter of 14.02 ± 2.10 nm and length of 619.6 ± 90.7 nm. The aspect ratio of the CNFs is in the range of long fibrils, that is 44.18. XRD studies revealed that CNFs (48.83%) were more crystalline than the banana bran (27.76%). TGA and derivative thermogravimetry thermograms showed that CNFs were more thermally stable than the bran.

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