Enhancement of Ultraviolet Emission of ZnO Hollow Nanofibers

2014 ◽  
Vol 971-973 ◽  
pp. 244-248
Author(s):  
Hai Ping Wang
Keyword(s):  
Electron Microscopy ◽  
Great Decrease ◽  
X Ray Diffraction ◽  
Hollow Nanofibers ◽  
Ultraviolet Emission ◽  
Bonding Structure ◽  
Interstitial Zinc ◽  
Transmission Electron ◽  
Uv Raman ◽  
Reactive Mechanism

ZnO hollow nanofibers were fabricated by sputtering using electrospun PVP nanofibers as templates. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV Raman were used to characterize the morphologies, crystal configuration and bonding structure of ZnO hollow nanofibers. A reactive mechanism of the transformation from poor polycrystalline ZnO (Zn-rich) prepared by sputtering from a metallic Zn target to good polycrystalline ZnO after annealing is proposed. The mechanism results in great decrease of oxygen vacancies and interstitial zinc of the ZnO hollow nanofibers after annealing. Optical properties were investigated by the photoluminescence spectra. Enhancement of ultraviolet emission of the ZnO hollow nanofibers is discussed.

scholarly journals CATALYST–FREE GROWTH OF WELL–ALIGNED ZnO NANOWIRES ON GRAPHENE/Si SUBSTRATEBY THERMAL EVAPORATION

2018 ◽  
Vol 55 (1B) ◽  
pp. 174
Author(s):  
Tran Van Khai
Keyword(s):  
Electron Microscopy ◽  
Thermal Evaporation ◽  
Substrate Surface ◽  
Zinc Powder ◽  
X Ray Diffraction ◽  
Ultraviolet Emission ◽  
Hexagonal Wurtzite Crystal Structure ◽  
Transmission Electron ◽  
Strong Ultraviolet Emission ◽  
Hexagonal Wurtzite Crystal

Vertically well–aligned ZnO nanowire (NW) arrays with high density were directly synthesized on graphene/Si substrate by thermal evaporation of zinc powder without catalysts or additives. The ZnO NWs were characterized by field emission scanning electron microscopy (FE–SEM), high resolution transmission electron microscopy (HRTEM), X–ray diffraction (XRD), photoluminescence (PL), and Raman spectroscopy. The results showed that the obtained ZnO NWs have diameters in the range of 300–350 nm with lengths of several tens micrometers. The prepared ZnO NWs are of a single crystal, which have a hexagonal wurtzite crystal structure with c–axis (002) orientation growth perpendicular to the substrate surface. The NW arrays had a good crystal quality with excellent optical properties, indicating a sharp and strong ultraviolet emission at 380 nm, and a weak visible emission at around 516 nm. 

Synthesis of LiCl Doped Hollow TiO2 Nanofibers via Electrospinning and Their Humidity-Sensing Properties

2012 ◽  
Vol 476-478 ◽  
pp. 1116-1120
Author(s):  
Hui Min Huang ◽  
Jie Yu ◽  
Ce Wang
Keyword(s):  
Electron Microscopy ◽  
X Ray Diffraction ◽  
Hollow Nanofibers ◽  
Humidity Sensing ◽  
Sensing Properties ◽  
Transmission Electron ◽  
Response And Recovery ◽  
Doped Titania ◽  
The Relationship ◽  
Humidity Sensing Properties

LiCl doped titania (TiO2) hollow nanofibers were prepared by using polylactide (PLA) nanofibers as templates. The morphology and crystal structure of the TiO2hollow nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The as-prepared LiCl doped TiO2hollow nanofibers exhibited a good humidity-sensing property. During the relative humidity (50%-95%) measurement, the response and recovery time is about 3 and 4 s, separately, with good linearity. The relationship between the humidity-sensing properties and the structure of the hollow nanofibers was also discussed. These distinguished and sensitive sensing performances make this material a good candidate in fabricating humidity sensors.

Enhanced photodegradation activity of electrospun porous TiO2 fibers

2019 ◽  
Vol 12 (06) ◽  
pp. 1941002 ◽  
Author(s):  
Peng Zhao ◽  
Peipei Huo ◽  
Xinxu Han ◽  
Bo Liu
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Anatase Phase ◽  
Mesoporous Structure ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
Hollow Nanofibers ◽  
X Ray ◽  
Transmission Electron ◽  
Calcination Method

Mesoporous titanium dioxide (TiO2) hollow nanofibers (HNFs) were successfully prepared by a facile electrospinning and calcination method. Techniques such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize TiO2 fibers. It was revealed that TiO2 crystals with an appropriate anatase fraction (71.58%) were grown and a tubular mesoporous structure was formed with a high specific surface area. Photodecomposition of methyl orange (MO) solution showed that TiO2 HNFs exhibited much higher photocatalytic activity than corresponding TiO2 nanofibers (NFs) and loose-structured nanofibers (LNFs). The significant enhancement of photocatalytic activity was attributed to both the sufficient growth of active anatase phase primarily and a tubular mesoporous nature of TiO2 HNFs.

SYNTHESIS, STRUCTURE, AND LUMINESCENCE PROPERTIES OF ZnSnO3 NANOWIRES

NANO ◽  
2012 ◽  
Vol 07 (02) ◽  
pp. 1250013 ◽  
Author(s):  
SOYEON AN ◽  
CHANGHYUN JIN ◽  
HYUNSU KIM ◽  
SANGMIN LEE ◽  
BONGYONG JEONG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Green Emission ◽  
Blue Shift ◽  
Zno Nanowires ◽  
X Ray Diffraction ◽  
Ultraviolet Emission ◽  
Violet Emission ◽  
X Ray ◽  
Transmission Electron

ZnSnO3 nanowires were synthesized on Si substrates by thermal evaporation of a mixture of ZnO, SnO2 and graphite powders. The nanowires were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The ZnSnO3 nanowires varied from 10 to 100 nm in diameter and up to a few hundred of micrometers in length. Transmission electron microscopy and X-ray diffraction revealed that the nanowires are multiphase nanostructures containing ZnSnO3, Zn2SnO4, ZnO, and SnO2 phases. Photoluminescence measurements showed that ZnSnO3 nanowires had a sharp ultraviolet emission peak at approximately 375 nm as well as a broad green emission band centered at approximately 510 nm. The violet emission of ZnSnO3 nanowires exhibits a blue shift by approximately 5 nm compared to that of ZnO nanowires and the visible emission of ZnO nanowires shifted from the orange region to the green region, which should be attributed to the narrowing of Eg. Thermal annealing enhanced the green emission but degraded the ultraviolet emission of the ZnSnO3 nanowires. In addition, the origin of the enhanced luminescence of ZnSnO3 nanowires compared to ZnO and SnO2 nanowires is discussed.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Epitaxy and texture analysis of Bi-Sr-Ca-Cu-O thin films on (100) MgO using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 68-69
Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Critical Currents ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Cell Axis ◽  
Transmission Electron ◽  
Synthesis Procedure

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).

Devitrification products of rapidly solidified Ni-Nb amorphous alloys.

1990 ◽  
Vol 48 (4) ◽  
pp. 950-951
Author(s):  
G. A. Bertero ◽  
W.H. Hofmeister ◽  
N.D. Evans ◽  
J.E. Wittig ◽  
R.J. Bayuzick
Keyword(s):  
Electron Microscopy ◽  
Amorphous Structure ◽  
Sulphuric Acid Solution ◽  
X Ray Diffraction ◽  
High Fracture ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Rapidly Solidified ◽  
Electromagnetically Levitated

Rapid solidification of Ni-Nb alloys promotes the formation of amorphous structure. Preliminary results indicate promising elastic properties and high fracture strength for the metallic glass. Knowledge of the thermal stability of the amorphus alloy and the changes in properties with temperature is therefore of prime importance. In this work rapidly solidified Ni-Nb alloys were analyzed with transmission electron microscopy (TEM) during in-situ heating experiments and after isothermal annealing of bulk samples. Differential thermal analysis (DTA), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques were also used to characterize both the solidification and devitrification sequences.Samples of Ni-44 at.% Nb were electromagnetically levitated, melted, and rapidly solidified by splatquenching between two copper chill plates. The resulting samples were 100 to 200 μm thick discs of 2 to 3 cm diameter. TEM specimens were either ion-milled or alternatively electropolished in a methanol-10% sulphuric acid solution at 20 V and −40°C.

Defect morphology in thick relaxed layers of InGaAs on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 668-669
Author(s):  
R H Dixon ◽  
P Kidd ◽  
P J Goodhew
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Strained Layers ◽  
Good Surface ◽  
Transmission Electron ◽  
Device Structures ◽  
Surface Morphologies

Thick relaxed InGaAs layers grown epitaxially on GaAs are potentially useful substrates for growing high indium percentage strained layers. It is important that these relaxed layers are defect free and have a good surface morphology for the subsequent growth of device structures.3μm relaxed layers of InxGa1-xAs were grown on semi - insulating GaAs substrates by Molecular Beam Epitaxy (MBE), where the indium composition ranged from x=0.1 to 1.0. The interface, bulk and surface of the layers have been examined in planar view and cross-section by Transmission Electron Microscopy (TEM). The surface morphologies have been characterised by Scanning Electron Microscopy (SEM), and the bulk lattice perfection of the layers assessed using Double Crystal X-ray Diffraction (DCXRD).The surface morphology has been found to correlate with the growth conditions, with the type of defects grown-in to the layer (e.g. stacking faults, microtwins), and with the nature and density of dislocations in the interface.

Synthesis of ZnO/ZnFe2O4 nanocomposites in organic-free media and their photocatalytic activity under natural sunlight

2020 ◽  
Vol 14 (2) ◽  
pp. 6801-6810
Author(s):  
Rahmayeni Rahmayeni ◽  
Zulhadjri Zulhadjri ◽  
Yeni Stiadi ◽  
Agusnar Harry ◽  
Syukri Arief
Keyword(s):  
Electron Microscopy ◽  
Hexagonal Wurtzite Structure ◽  
Rice Grain ◽  
X Ray Diffraction ◽  
Homogeneous Sphere ◽  
Natural Sunlight ◽  
Transmission Electron ◽  
Photocatalytic Activities ◽  
Free Media ◽  
Photocatalytic Applications

Nanocomposite ZnO/ZnFe2O4 photocatalysts with different proportions of ZnFe2O4 were synthesized in organic-free media using metal nitric as precursors. The ZnO phase with hexagonal wurtzite structure and low crystallinity of ZnFe2O4 was confirmed using XRD (X-Ray diffraction). Different morphologies of the nanocomposites were obtained ranging from rice grain-like with a porous surface to homogeneous sphere-like nanoparticles as shown in Scanning Electron Microscopy (SEM) and TEM Transmission Electron Microscopy (TEM) studies. Magnetic properties measured by Visible Sampler Magnetometer (VSM) showed diamagnetic and paramagnetic behavior for the nanocomposites. Analysis with Diffuse Reflectance Spectrophotometer (DRS) UV-vis showed an increase the composition of ferrite in composites increasing its ability to absorb visible light. Photocatalytic activities of ZnO/ZnFe2O4 nanocomposites on the degradation of Rhodamine B dye reached 95.6% after 3 h under natural sunlight suggesting their suitability for sunlight driven photocatalytic applications. 

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