Flame Synthesis of ZnO Nanostructures: Morphology and Local Growth Conditions

2008 ◽  
Author(s):  
Stephen Tse ◽  
Fusheng Xu ◽  
Cassandra D'Esposito ◽  
Xiaofei Liu ◽  
Bernard Kear
Keyword(s):  
Growth Conditions ◽  
Flame Synthesis ◽  
Zno Nanostructures ◽  
Local Growth

Diffraction from arrays of antiphase boundaries in ordered III-V alloys

1987 ◽  
Vol 45 ◽  
pp. 312-313
Author(s):  
T. S. Kuan
Keyword(s):  
High Surface ◽  
Growth Conditions ◽  
Ternary Alloys ◽  
Local Growth ◽  
Antiphase Boundaries ◽  
Surface Mobility ◽  
Ordered Phases ◽  
Diffraction Patterns ◽  
Atomically Flat ◽  
Degree Of Order

Recent electron diffraction studies have found ordered phases in AlxGa1-xAs, GaAsxSb1-x, and InxGa1-xAs alloy systems, and these ordered phases are likely to be found in many other III-V ternary alloys as well. The presence of ordered phases in these alloys was detected in the diffraction patterns through the appearance of superstructure reflections between the Bragg peaks (Fig. 1). The ordered phase observed in the AlxGa1-xAs and InxGa1-xAs systems is of the CuAu-I type, whereas in GaAsxSb1-x this phase and a chalcopyrite type ordered phase can be present simultaneously. The degree of order in these alloys is strongly dependent on the growth conditions, and during the growth of these alloys, high surface mobility of the depositing species is essential for the onset of ordering. Thus, the growth on atomically flat (110) surfaces usually produces much stronger ordering than the growth on (100) surfaces. The degree of order is also affected by the presence of antiphase boundaries (APBs) in the ordered phase. As shown in Fig. 2(a), a perfectly ordered In0.5Ga0.5As structure grown along the <110> direction consists of alternating InAs and GaAs monolayers, but due to local growth fluctuations, two types of APBs can occur: one involves two consecutive InAs monolayers and the other involves two consecutive GaAs monolayers.

ZnO Nanostructures and Field Emission Properties on Cu Substrate Achieved by Electrodeposition Method

2011 ◽  
Vol 347-353 ◽  
pp. 3388-3391
Author(s):  
Jiang Feng Gong ◽  
Chang Yong Lan ◽  
Bo Zhang ◽  
Kai Xiao Zhang ◽  
Wei Hua Zhu
Keyword(s):  
Electron Microscopy ◽  
Field Emission ◽  
Growth Conditions ◽  
Zno Nanostructures ◽  
Emission Properties ◽  
Electrodeposition Method ◽  
Field Emission Properties ◽  
Field Emitters ◽  
Transmission Electron ◽  
Cu Substrates

In the present work, ZnO nanostructures with tunable size were successfully synthesized on non-seeded Cu substrates by a simple electrodeposition method. The effects of growth conditions on the morphology of the products were studied in detail by scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-prepared products exhibited flake-like morphology when the concentration of ZnCl2 was higher enough, while the products showed flower-like morphology when the concentration was lower enough. Field emission investigation indicated that the nanoflowers exhibited good emission properties. The ZnO nanoflowers show potential application as field emitters.

scholarly journals Existence of Mild Solutions for a Class of Fractional Evolution Equations with Compact Analytic Semigroup

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
He Yang
Keyword(s):  
Analytic Semigroup ◽  
Evolution Equations ◽  
Mild Solutions ◽  
Fractional Power ◽  
Growth Conditions ◽  
Local Growth ◽  
Fractional Evolution Equations ◽  
Nonlinear Part ◽  
Compact Analytic Semigroup

This paper deals with the existence of mild solutions for a class of fractional evolution equations with compact analytic semigroup. We prove the existence of mild solutions, assuming that the nonlinear part satisfies some local growth conditions in fractional power spaces. An example is also given to illustrate the applicability of abstract results.

scholarly journals The Influence of Growth Rate on Porosity in Al-Pd-Mn Icosahedral Quasicrystals.

2000 ◽  
Vol 643 ◽  
Author(s):  
Amy R. Ross ◽  
Ian R. Fisher ◽  
Paul C. Canfield ◽  
Thomas A. Lograsso
Keyword(s):  
Growth Rate ◽  
Crystal Size ◽  
Growth Conditions ◽  
Flux Growth ◽  
Local Growth ◽  
Cooling Rates ◽  
Porosity Level ◽  
Growth Method ◽  
Icosahedral Quasicrystals ◽  
Growth Experiments

AbstractGrowth experiments have been carried out to characterize the occurrence and development of porosity in Bridgman and flux grown Al-Pd-Mn icosahedral quasicrystals. The porosity level has been observed to fluctuate between values of 0.0 and 3.75 percent along the length of Bridgman single crystals implying that the development of porosity is affected by the local growth conditions. Experiments were conducted to evaluate the influence of the rate of solidification on the occurrence of porosity. Alloys were solidified with different growth rates, 1mm/hr and >10 mm/hr, using the Bridgman configuration and at different cooling rates, ranging from 0.29°C/hr to 10°C/hr, using the flux growth method. Porosity levels were analyzed via optical image analysis. These experiments indicate that porosity percentages are greatly influenced by cooling rates and crystal size.

Pit and pit aperture dimensions in plantation-grown Douglas fir as affected by local growth conditions and height in stem

IAWA Journal ◽  
2020 ◽  
Vol 41 (2) ◽  
pp. 131-140
Author(s):  
Andreas Christof ◽  
Anders Ræbild ◽  
Lisbeth G. Thygesen
Keyword(s):  
Environmental Factors ◽  
Soil Fertility ◽  
Pseudotsuga Menziesii ◽  
Allometric Scaling ◽  
Growth Conditions ◽  
Douglas Fir ◽  
Model Fit ◽  
The Other ◽  
Local Growth ◽  
Poor Soil

Abstract This study assessed whether allometric scaling applied to pit sizes in stems of Douglas fir. Pit and pit aperture diameters were measured in xylem from stems of four plantation-grown Douglas fir (Pseudotsuga menziesii) trees from each of two different sites in Denmark. One site had fertile soil, the other had poor soil fertility. Three different heights were accessed for each tree, and 40 pits were measured per height. Results showed that pit diameter varied between 17 and 24 μm and decreased significantly with increasing height above ground. Representing the position in the tree as a power function of distance from the top of the tree (L0.2) rather than the height above ground improved the model fit for pit diameter as expressed by the R2 value. However, the pit diameter relationship was found to be significantly affected by site, suggesting that anatomic dimensions relate not only to tree size but also to growth conditions. This would imply that even though pit size supposedly has a strong biophysical determination, some xylem plasticity may still be induced by environmental factors.

Morphology-dependent luminescence from ZnO nanostructures — An X-ray excited optical luminescence study at the Zn K-edge

2009 ◽  
Vol 87 (9) ◽  
pp. 1255-1260 ◽  
Author(s):  
Olga Lobacheva ◽  
Michael W. Murphy ◽  
Jun Young Peter Ko ◽  
Tsun-Kong Sham
Keyword(s):  
Gas Flow ◽  
Thermal Evaporation ◽  
Growth Conditions ◽  
Zno Nanostructures ◽  
Edge Structure ◽  
X Ray ◽  
Si Substrates ◽  
Optical Luminescence ◽  
Carrier Gas Flow ◽  
X Ray Absorption

ZnO nanostructures have been synthesized by thermal evaporation on Si substrates. It is found that the morphologies of the nanostructures are governed by growth conditions such as temperature, carrier-gas flow rate, and the nature of the substrate (with and without a catalyst). We report X-ray excited optical luminescence from ZnO nanostructures of distinctly different morphologies in the energy and time domain using excitation photon energies across the Zn K-edge. X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study has clearly shown the morphology dependence of the ZnO optical properties. A correlation of luminescence with morphology, size, and crystallinity emerges.

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