MODULATION OF PTCDA NANOSTRUCTURE AND OPTICAL PROPERTY: DEPENDENCE ON GROWTH TEMPERATURE

NANO ◽  
2014 ◽  
Vol 09 (06) ◽  
pp. 1450068
Author(s):  
PANPAN GUO ◽  
YUYAN HAN ◽  
WENHUA ZHANG ◽  
LINGYUN LIU ◽  
KAI WANG ◽  
...  
Keyword(s):  
Optical Properties ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Potential Applications ◽  
Organic Optoelectronic Devices ◽  
Organic Optoelectronic ◽  
Tetracarboxylic Dianhydride

3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) nanostructures with different morphologies are prepared on glass substrates at different substrate temperature (Ts) in a molecular beam epitaxy (MBE) system. Scanning/transmission/scanning transmission electron microscopy (SEM/TEM/STEM), X-ray diffraction (XRD), selected area electron diffraction (SAED) and nanobeam diffraction (NBD) techniques are employed in the systematical characterizations of the nanostructures. It is found that the PTCDA nanosheets (NSs), nanowires and nanorods are facile to produce at Ts = 350° C , 330°C and 240°C, respectively; the continuous films are obtained at 180°C and 50°C. XRD studies indicate that only the α-phase polymorph is formed regardless of the Ts. SAED and NBD results show that the nanowire and NS are single crystalline. The optical properties of the prepared PTCDA nanostructures are also found to be influenced by Ts and are correlated with the crystal quality and size. PTCDA nanowires and NSs exhibit an obvious redshift and broadening in the adsorption spectra, and enhanced emission intensity. The improved optical properties facilitate potential applications of these nanostructures in organic optoelectronic devices.

scholarly journals Synthesis and optical properties of self-assembled flower-like CdS architectures by mixed solvothermal process

2010 ◽  
Vol 8 (5) ◽  
pp. 1027-1033 ◽  
Author(s):  
Junhao Zhang ◽  
Yuhui Wu ◽  
Jia Zhu ◽  
Shaoxing Huang ◽  
Dongjing Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Optical Properties ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
Strong Emission ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Self Assembled ◽  
Xrd Patterns ◽  
Hexagonal Wurtzite Phase

AbstractSelf-assembled CdS architectures with flower-like structures have been synthesized by a mixed solvothermal method using ethylene glycol and oleic acid as the mixed solvent at 160°C for 12 h. The results of X-ray diffraction (XRD) patterns, field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the product exists as the hexagonal wurtzite phase and conatins of larger numbers of flower-like CdS architectures with diameters of 1.8–3 μm. The selected-area electron diffraction (SAED) pattern and the high resolution transmission electron microscope (HRTEM) image reveal that the grain has better crystallinity. The optical properties of flower-like CdS architectures were also investigated by ultraviolet-visable (UV-vis) and photoluminescence spectroscopy at room temperature. A strong peak at 490 nm is shown in the UV-vis absorption, while an emission at 486 nm and another strong emission at 712 nm are shown in the PL spectrum.

scholarly journals Characterization Microstructural and Electrochemical of AgPd Alloy Bimetallic Nanoparticles

MRS Advances ◽  
2017 ◽  
Vol 2 (50) ◽  
pp. 2857-2863 ◽  
Author(s):  
A. Santoveña ◽  
C. Rodriguez-Proenza ◽  
J.A. Maya-Cornejo ◽  
A. Ruiz-Baltazar ◽  
D. Bahena ◽  
...  
Keyword(s):  
Bimetallic Nanoparticles ◽  
Electrochemical Characterizations ◽  
Dark Field ◽  
High Catalytic Activity ◽  
X Ray Diffraction ◽  
Bimetallic Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Potential Applications

ABSTRACTBimetallic nanoparticles are of special interest for their potential applications to fuel cells, among the bimetallic systems, AuPd bimetallic nanoparticles have received great interest as they can be widely used as effective catalysts for various electrochemical reactions. Monodisperse AgPd alloy nanoparticles were synthesized by polyol method using silver nitrate and potassium tetrachloropalladate(II) in ethylene glycol as the reducing agent at 160 °C. Structural, compositional and electrochemical characterizations of synthesized bimetallic nanoparticles were investigated. High-angle annular dark field scanning/transmission electron microscopy (HAADF-STEM) images and parallel beam X-ray diffraction (XRD) of the bimetallic nanoparticles were obtained. XRD and the contrast of the HAADF-STEM images show that the bimetallic nanoparticles have an alloy structure. Cyclic voltammetry was carried out in order to confirm the electrochemical responses of the AgPd/C electrocatalysts for methanol oxidation. Thanks to the narrow size distribution of the AgPd alloy bimetallic nanoparticles (9.15 nm) the supported AgPd/C electrocatalysts have high catalytic activity toward methanol electro-oxidation.

scholarly journals Microstructure and Optical Characterization of Mid-Wave HgCdTe grown by MBE under Different Conditions

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 296
Author(s):  
Xiao-fang Qiu ◽  
Sheng-xi Zhang ◽  
Jian Zhang ◽  
Yi-cheng Zhu ◽  
Cheng Dou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Growth Temperature ◽  
Crystal Quality ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Lower Temperature

The mid-wave single-crystal HgCdTe (211) films were successfully grown on GaAs (211) B substrates by molecular beam epitaxy (MBE). Microstructure and optical properties of the MBE growth HgCdTe films grown at different temperatures were characterized by X-ray diffraction, scanning transmission electron microscopy, Raman and photoluminescence. The effects of growth temperature on the crystal quality of HgCdTe/CdTe have been studied in detail. The HgCdTe film grown at the lower temperature of 151 °C has high crystal quality, the interface is flat and there are no micro twins. While the crystal quality of the HgCdTe grown at higher temperature of 155 °C is poor, and there are defects and micro twins at the HgCdTe/CdTe interface. The research results demonstrate that the growth temperature significantly affects the crystal quality and optical properties of HgCdTe films.

Phase Formation in a Wedged Au-Ag-Cu Multilayered Structure

1993 ◽  
Vol 311 ◽  
Author(s):  
I. Goldfarb ◽  
E. Zolotoyabko ◽  
D. Shechtman
Keyword(s):  
Electron Microscopy ◽  
Phase Formation ◽  
Multilayered Structure ◽  
Heat Treatments ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Xrd Patterns

ABSTRACTAn advanced method for investigation of multicomponent systems is proposed. Thin wedged-shape films of pure components are subsequently deposited to form a multilayered structure with continuously-varying composition as a function of sample location, providing a large number of differently composed samples in one deposition run. Each sample is then subjected to various heat treatments, and phase content as well as the microstructure formed is under investigation.In this study an Au-Ag-Cu multilayered structure was sputtered at a room temperature onto 55 Formvar-coated Mo grids. The satellite-like X-Ray Diffraction (XRD) patterns of these samples revealed the formation of an artificial composition-modulated ternary superlattice, complete destruction of which was observed during heat treatments, where phase formation according to the ternary Au-Ag-Cu phase diagram took place.Several aspects of phase formation were analyzed using XRD, Electron Probe for Micro- Analysis (EPMA) in Scanning Electron Microscopy (SEM), and Scanning Transmission Electron Microscopy (STEM) combined with Selected Area Electron Diffraction (SAED), Digital X-Ray Mapping (DXM), Secondary Electron Mapping and EPMA methods.

Electrochemical Formation of Elemental Boron in LiCl–KCl–KBF4 at 723 K

2021 ◽  
Author(s):  
Yumi Katasho ◽  
Tetsuo Oishi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Scanning Transmission Electron Microscope ◽  
X Ray Diffraction ◽  
Recycling Process ◽  
Reduction Behavior ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Elemental Boron ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract The electrochemical reduction behavior of B(III) ions was investigated in LiCl–KCl–KBF4 at 723 K. The results of cyclic voltammetry using Mo, Ag, and Ni electrodes suggested the reduction of B(III) to B(0) at potentials of 1.5 V or at a more negative potential (vs. Li+/Li). Spherical electrodeposits were observed after potentiostatic electrolysis at 1.1–1.5 V. From the results of X-ray photoelectron spectroscopy, scanning transmission electron microscope/energy-dispersive X-ray spectroscopy (STEM/EDX), and selected area electron diffraction, it was concluded that the spherical electrodeposits obtained at 1.1 V were elemental amorphous boron. The purity of the products was 85 wt% boron, as determined by STEM/EDX analysis. The current efficiency of elemental B electrodeposition was 96.2% in this system. The formation of Ni2B at 1.1–1.9 V was indicated by X-ray diffraction, although it was not the main product. These results indicate that the presence of B(III) ions in a melt causes a fatal adverse effect on the recycling process of Nd–Fe–B magnets due to the reduction of B(III) ions. Further, the possibility of reducing the energy and cost of the elemental boron production process was discussed.

Fabrication and Characterization of Transparent Conducting ZnO: Al Films for Organic Optoelectronic Devices

2012 ◽  
Vol 502 ◽  
pp. 72-76 ◽  
Author(s):  
Zhi You Zhong ◽  
J. Zhou ◽  
J.H. Gu ◽  
X. He ◽  
J. Hou ◽  
...  
Keyword(s):  
Hexagonal Wurtzite Structure ◽  
Rf Magnetron Sputtering ◽  
Optical Transmittance ◽  
Discharge Power ◽  
Visible Range ◽  
X Ray Diffraction ◽  
Glass Substrates ◽  
Average Optical Transmittance ◽  
Organic Optoelectronic Devices ◽  
Organic Optoelectronic

Al-doped ZnO (ZnO:Al) thin films were deposited on glass substrates by rf magnetron sputtering technique. The effect of discharge power on the structural, optical and electrical characteristics of ZnO:Al films was investigated by X-ray diffraction (XRD), four-probe meter and optical transmission spectroscopy. The results show that the films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The highest figure of merit of 5.58×10-3 -1 is obtained from the film prepared at the discharge power of 200 W. The average optical transmittance in the visible range of the films is over 78.2%.

Surfactant involved in Copper Sulfide Nanocrystallites Synthesis

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Claudia Maria Simonescu ◽  
Valentin Serban Teodorescu ◽  
Camelia Capatina
Keyword(s):  
Copper Sulfide ◽  
X Ray Diffraction ◽  
Reaction Parameters ◽  
Reaction Conditions ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Shape Of Nanoparticles ◽  
Tem Transmission Electron Microscopy ◽  
Shape And Size

This paper presents the obtaining of copper sulfide CuS (covelite) from Cu(CH3COO)2.H2O and thioacetamide (TAA) system. The reaction was conducted in presence or absence of sodium-bis(2-ethylhexyl) sulfosuccinate (Na-AOT). The effects of various reaction parameters on the size and on the shape of nanoparticles have been examined. CuS obtained was characterized by X ray diffraction, IR spectroscopy, TEM � transmission electron microscopy and SAED selected area electron diffraction. The influence of surfactant to the shape and size of CuS (covellite) nanocrystals was established. The size of the nanocrystals varied from 10-60 nm depending on the reaction conditions such as quantity of surfactant.

scholarly journals Microstructure and properties of nano-laminated Y3Si2C2 ceramics fabricated via in situ reaction by spark plasma sintering

2021 ◽  
Vol 10 (3) ◽  
pp. 578-586
Author(s):  
Lin-Kun Shi ◽  
Xiaobing Zhou ◽  
Jian-Qing Dai ◽  
Ke Chen ◽  
Zhengren Huang ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Atomic Scale ◽  
Max Phase ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Spark Plasma ◽  
Diffraction Patterns

AbstractA nano-laminated Y3Si2C2 ceramic material was successfully synthesized via an in situ reaction between YH2 and SiC using spark plasma sintering technology. A MAX phase-like ternary layered structure of Y3Si2C2 was observed at the atomic-scale by high resolution transmission electron microscopy. The lattice parameters calculated from both X-ray diffraction and selected area electron diffraction patterns are in good agreement with the reported theoretical results. The nano-laminated fracture of kink boundaries, delamination, and slipping were observed at the tip of the Vickers indents. The elastic modulus and Vickers hardness of Y3Si2C2 ceramics (with 5.5 wt% Y2O3) sintered at 1500 °C were 156 and 6.4 GPa, respectively. The corresponding values of thermal and electrical conductivity were 13.7 W·m-1·K-1 and 6.3×105 S·m-1, respectively.

scholarly journals Temperature Dependence of Stress and Optical Properties in AlN Films Grown by MOCVD

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 698
Author(s):  
Wenwang Wei ◽  
Yi Peng ◽  
Jiabin Wang ◽  
Muhammad Farooq Saleem ◽  
Wen Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Compressive Stress ◽  
Sapphire Substrate ◽  
Light Transmission ◽  
Chemical Vapor ◽  
Biaxial Stress ◽  
X Ray Diffraction ◽  
Patterned Sapphire Substrate ◽  
Transmission Electron ◽  
Nano Patterning

AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes.

Solvothermal Synthesis of Bi2Se3 Hexagonal Nanosheet Crystals

2011 ◽  
Vol 236-238 ◽  
pp. 1712-1716 ◽  
Author(s):  
Hai Tao Liu ◽  
Jun Dai ◽  
Jia Jia Zhang ◽  
Wei Dong Xiang
Keyword(s):  
Electron Microscope ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Electron

Bismuth selenide (Bi2Se3) hexagonal nanosheet crystals with uniform size were successfully prepared via a solvothermal method at 160°C for 22 h using bismuth trichloride(BiCl3) and selenium powder(Se) as raw materials, sodium bisulfite(NaHSO3) as a reducing agent, diethylene glycol(DEG) as solvent, and ammonia as pH regulator. Various techniques such as X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), and selected area electron diffraction (SAED) were used to characterize the obtained products. Results show that the as-synthesized samples are pure Bi2Se3 hexagonal nanosheet crystals. A possible growth mechanism for Bi2Se3 hexagonal nanosheet crystals is also discussed based on the experiment.

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