Role of Oxygen Adatoms in Homoepitaxial Growth of Cu(001)

1998 ◽  
Vol 528 ◽  
Author(s):  
Masanori Yata ◽  
Herve Rouch ◽  
Keikichi Nakamura
Keyword(s):  
Exchange Rate ◽  
Transition Temperature ◽  
Barrier Height ◽  
Deposition Rate ◽  
Layer By Layer ◽  
Step Flow ◽  
Homoepitaxial Growth ◽  
Arrhenius Relation ◽  
Site Exchange

AbstractO atoms segregate to the surface during Cu homoepitaxial growth on Cu(001)-(2√2×√2)-O to retain the (2√2×√2) surface. The presence of an O adlayer on the Cu surface raises the barrier height for the surface diffusion of the Cu adatom and increases the transition temperature of the growth mode from step flow to layer by layer. The growth proceeds by site exchange between Cu adatoms and O atoms. The site-exchange rate competes with the Cu deposition rate. There exists a critical Cu deposition rate above which the O atoms can not exchange the sites with Cu adatoms. The critical Cu deposition rate obeys an Arrhenius relation and the active energy for the site-exchange is estimated at 0.66 eV.

Oblique-incidence Reflectivity Difference (OI-RD) and Leed Studies of Adsorption and Growth of Xe on Nb(110)

2003 ◽  
Vol 780 ◽  
Author(s):  
P. Thomas ◽  
E. Nabighian ◽  
M.C. Bartelt ◽  
C.Y. Fong ◽  
X.D. Zhu
Keyword(s):  
Transition Layer ◽  
Layer Growth ◽  
Flow Mode ◽  
Layer By Layer ◽  
Zeroth Order ◽  
Step Flow ◽  
Low Energy Electron Diffraction ◽  
Oriented Film ◽  
Low Energy Electron

AbstractWe studied adsorption, growth and desorption of Xe on Nb(110) using an in-situ obliqueincidence reflectivity difference (OI-RD) technique and low energy electron diffraction (LEED) from 32 K to 100 K. The results show that Xe grows a (111)-oriented film after a transition layer is formed on Nb(110). The transition layer consists of three layers. The first two layers are disordered with Xe-Xe separation significantly larger than the bulk value. The third monolayer forms a close packed (111) structure on top of the tensile-strained double layer and serves as a template for subsequent homoepitaxy. The adsorption of the first and the second layers are zeroth order with sticking coefficient close to one. Growth of the Xe(111) film on the transition layer proceeds in a step flow mode from 54K to 40K. At 40K, an incomplete layer-by-layer growth is observed while below 35K the growth proceeds in a multilayer mode.

scholarly journals Modeling the Layer-by-Layer Growth of HKUST-1 Metal-Organic Framework Thin Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1631
Author(s):  
Qiang Zhang ◽  
Yohanes Pramudya ◽  
Wolfgang Wenzel ◽  
Christof Wöll
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Deposition Rate ◽  
Layer Growth ◽  
Coarse Grained ◽  
Structural Defects ◽  
Effect Of Temperature ◽  
Layer By Layer ◽  
Reactant Concentration ◽  
Metal Organic

Metal organic frameworks have emerged as an important new class of materials with many applications, such as sensing, gas separation, drug delivery. In many cases, their performance is limited by structural defects, including vacancies and domain boundaries. In the case of MOF thin films, surface roughness can also have a pronounced influence on MOF-based device properties. Presently, there is little systematic knowledge about optimal growth conditions with regard to optimal morphologies for specific applications. In this work, we simulate the layer-by-layer (LbL) growth of the HKUST-1 MOF as a function of temperature and reactant concentration using a coarse-grained model that permits detailed insights into the growth mechanism. This model helps to understand the morphological features of HKUST-1 grown under different conditions and can be used to predict and optimize the temperature for the purpose of controlling the crystal quality and yield. It was found that reactant concentration affects the mass deposition rate, while its effect on the crystallinity of the generated HKUST-1 film is less pronounced. In addition, the effect of temperature on the surface roughness of the film can be divided into three regimes. Temperatures in the range from 10 to 129 °C allow better control of surface roughness and film thickness, while film growth in the range of 129 to 182 °C is characterized by a lower mass deposition rate per cycle and rougher surfaces. Finally, for T larger than 182 °C, the film grows slower, but in a smooth fashion. Furthermore, the potential effect of temperature on the crystallinity of LbL-grown HKUST-1 was quantified. To obtain high crystallinity, the operating temperature should preferably not exceed 57 °C, with an optimum around 28 °C, which agrees with experimental observations.

Investigating the role of GeO2 in enhancing the thermal stability and proton mobility of proton-conducting phosphate glasses

2021 ◽  
Author(s):  
Takahisa Omata ◽  
Aman Sharma ◽  
Takuya Kinoshita ◽  
Issei Suzuki ◽  
Tomohiro Ishiyama ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Phosphate Glasses ◽  
Proton Mobility ◽  
Proton Conducting

In this study, the effect of GeO2 on the thermal stability and proton mobility (μH) of proton-conducting phosphate glasses was experimentally investigated using 22HO1/2−3NaO1/2−(12−x)LaO3/2−xGeO2−63PO5/2 glasses. Increasing glass transition temperature (Tg)...

scholarly journals Key Influencers in Public Diplomacy 2.0: A Country-Based Social Network Analysis

2021 ◽  
Vol 7 (1) ◽  
pp. 205630512098105
Author(s):  
Diana Ingenhoff ◽  
Giada Calamai ◽  
Efe Sevin
Keyword(s):  
New Media ◽  
Public Diplomacy ◽  
Qualitative Content Analysis ◽  
Dominant Role ◽  
Opinion Leaders ◽  
Centrality Measures ◽  
Political Actors ◽  
Step Flow ◽  
Twitter Users

This article presents a study of Twitter-based communication in order to identify key influencers and to assess the role of their communication in shaping country images. The analysis is based on a 2-month dataset comprised of all tweets including hashtags of the three countries selected for this study: Austria, Switzerland, and the Netherlands. Following a two-step flow model of communication, we initially identified the influential Twitter users in all three countries based on their centrality measures. Subsequently, we carried out a qualitative content analysis of tweets posted by these influential users. Finally, we assessed the similarities and differences across the three country cases. This article offers new insights into public diplomacy 2.0 activities by discussing influence within the context of country images and demonstrating how opinion leaders can play a more dominant role than states or other political actors in creating and disseminating content related to country image. The findings also provide practical insights in the production of a country’s image and its representation on new media platforms.

The Role of Azopolymer/Dendrimer Layer-by-Layer Film Architecture in Photoinduced Birefringence and the Formation of Surface-Relief Gratings

Langmuir ◽  
2006 ◽  
Vol 22 (14) ◽  
pp. 6177-6180 ◽  
Author(s):  
David S. dos Santos, ◽  
Marcos R. Cardoso ◽  
Fabio L. Leite ◽  
Ricardo F. Aroca ◽  
Luiz H. C. Mattoso ◽  
...  
Keyword(s):  
Surface Relief ◽  
Layer By Layer ◽  
Layer Film ◽  
Photoinduced Birefringence ◽  
Surface Relief Gratings
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