scholarly journals Suppression of sub-surface freezing in free-standing thin films of a coarse-grained model of water

2014 ◽  
Vol 16 (47) ◽  
pp. 25916-25927 ◽  
Author(s):  
Amir Haji-Akbari ◽  
Ryan S. DeFever ◽  
Sapna Sarupria ◽  
Pablo G. Debenedetti
Keyword(s):  
Thin Films ◽  
Coarse Grained ◽  
Free Standing ◽  
Coarse Grained Model ◽  
Crystalline Nucleus ◽  
Surface Freezing

An 850-molecule crystalline nucleus identified in simulations of a 5 nm film at 235 K showing liquid-like and solid-like molecules in blue and fuchsia, respectively.

Stress-Strain Curves by Tensile Testing of Thin Metallic Films On Thin Polyimide Foils: Al, AlCu, CuNi(Mn)

1997 ◽  
Vol 505 ◽  
Author(s):  
F. Macionczyk ◽  
W. Brückner ◽  
G. Reiss
Keyword(s):  
Thin Films ◽  
Tensile Testing ◽  
Bulk Material ◽  
Testing Machine ◽  
Tensile Tests ◽  
Coarse Grained ◽  
Free Standing ◽  
Stress Strain ◽  
Tensile Testing Machine ◽  
Film Substrate

ABSTRACTFor better understanding the mechanical properties of thin films it is helpful to use the same experimental methods as for bulk material, like tensile tests, thereby being able to directly compare the results. However, tensile tests of free-standing metallic thin films are often difficult to perform for reasons of preparation, handling, and stresses in the films. By leaving the metallic film on an elastic substrate tensile tests were performed in a rather simple and precise manner, using a commercial tensile testing machine. Stress-strain curves were determined by separating the force working on the substrate from that working on the film-substrate compound. Those measurements were done at room temperature for Al, AlCu(0. 5 wt %) and Cuo0.57Ni0.42Mn0.01 thin (200–2000 nm) films prepared by magnetron sputtering on 8 μm and 13 μm thick polyimide (Kapton) foils. The film microstructure was characterized by scanning and transmission electron microscopy and X-ray diffraction. The tensile strength of the fine grained films was found to be up to one order of magnitude higher than for the corresponding coarse grained bulk material. Al and AlCu films showed little, CuNi(Mn) films showed no plastical behavior. Crack formation started between 0.3 % and 2 % strain depending on the material, the thermal history, and the grain size.

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.

Polarization-dependence of the Raman response of free-standing strained Ce0.8Gd0.2O2 membranes

2021 ◽  
Author(s):  
Alexander Konetschny ◽  
Marcel Weinhold ◽  
Christian Heiliger ◽  
Matthias Thomas Elm ◽  
Peter J. Klar
Keyword(s):  
Thin Films ◽  
Strain State ◽  
Polarization Dependence ◽  
Raman Mapping ◽  
Free Standing ◽  
Excitation Light ◽  
Oriented Polycrystalline ◽  
Raman Response

Square-shaped Ce0.8Gd0.2O2 (GDC) membranes are prepared by microstructuring techniques from (111)-oriented, polycrystalline GDC thin films. The strain state of the membranes is investigated by micro-Raman mapping using polarized excitation light....

scholarly journals Vacuum-Free and Highly Dense Nanoparticle Based Low-Band-Gap CuInSe2 Thin-Films Manufactured by Face-to-Face Annealing with Application of Uniaxial Mechanical Pressure

Coatings ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 484
Author(s):  
Matthias Schuster ◽  
Dominik Stapf ◽  
Tobias Osterrieder ◽  
Vincent Barthel ◽  
Peter J. Wellmann
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Coarse Grained ◽  
High Porosity ◽  
Low Band Gap ◽  
Seeding Layer ◽  
X Ray ◽  
Face To Face ◽  
Copper Indium ◽  
Vis Spectroscopy

Copper indium gallium sulfo-selenide (CIGS) based solar cells show the highest conversion efficiencies among all thin-film photovoltaic competition. However, the absorber material manufacturing is in most cases dependent on vacuum-technology like sputtering and evaporation, and the use of toxic and environmentally harmful substances like H2Se. In this work, the goal to fabricate dense, coarse grained CuInSe2 (CISe) thin-films with vacuum-free processing based on nanoparticle (NP) precursors was achieved. Bimetallic copper-indium, elemental selenium and binary selenide (Cu2−xSe and In2Se3) NPs were synthesized by wet-chemical methods and dispersed in nontoxic solvents. Layer-stacks from these inks were printed on molybdenum coated float-glass-substrates via doctor-blading. During the temperature treatment, a face-to-face technique and mechanically applied pressure were used to transform the precursor-stacks into dense CuInSe2 films. By combining liquid phase sintering and pressure sintering, and using a seeding layer later on, issues like high porosity, oxidation, or selenium- and indium-depletion were overcome. There was no need for external Se atmosphere or H2Se gas, as all of the Se was directly in the precursor and could not leave the face-to-face sandwich. All thin-films were characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and UV/vis spectroscopy. Dense CISe layers with a thickness of about 2–3 µm and low band gap energies of 0.93–0.97 eV were formed in this work, which show potential to be used as a solar cell absorber.

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