Optimal Percolation Thresholds of Two- and Three-Dimensional Engineering Composites

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
X. Frank Xu
Keyword(s):  
Thin Films ◽  
Variational Method ◽  
Theoretical Prediction ◽  
Transport Properties ◽  
Three Dimensional ◽  
Engineering Applications ◽  
Aspect Ratios ◽  
Percolation Thresholds ◽  
Work Done ◽  
Properties Of Composites

Theoretical prediction of percolation thresholds universally applicable for various composites remains a major theoretical challenge. In the work done by Xu (2011, “Ellipsoidal Bounds and Percolation Thresholds of Transport Properties of Composites,” Acta Mech., 223, pp. 765–774), a variational method is developed to predict optimal percolation thresholds for transport properties of three dimensional composites subjected to full dispersion of fillers. In this paper, simplified formulae are provided for engineering applications of 3D composites. New formulae are derived for optimal percolation thresholds of 2D composites, i.e., laminates and thin films, and for composites containing a combination of fillers with different aspect ratios. The effects of dimensionality and waviness are especially discussed.

scholarly journals Three-dimensional strain engineering in epitaxial vertically aligned nanocomposite thin films with tunable magnetotransport properties

2018 ◽  
Vol 5 (3) ◽  
pp. 536-544 ◽  
Author(s):  
Xing Sun ◽  
Jijie Huang ◽  
Jie Jian ◽  
Meng Fan ◽  
Han Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Electrical Transport ◽  
Three Dimensional ◽  
Strain Engineering ◽  
Electrical Transport Properties ◽  
Nanocomposite Thin Films ◽  
Vertically Aligned ◽  
3D Framework

A novel three-dimensional (3D) framework with integrated lateral and vertical interfaces, enables the power of 3D strain tuning and improves its electrical transport properties.

Zero-Shrinkage Whisker Fraction in Ceramic Matrix-Ceramic Whisker Composites

1989 ◽  
Vol 155 ◽  
Author(s):  
Elizabeth A. Holm ◽  
M. J. Cima
Keyword(s):  
Computer Simulation ◽  
Monte Carlo ◽  
Three Dimensional ◽  
Ceramic Matrix ◽  
Ceramic Particle ◽  
Soft Core ◽  
Excluded Volume ◽  
Monte Carlo Computer Simulation ◽  
Aspect Ratios ◽  
Percolation Thresholds

ABSTRACTA Monte Carlo computer simulation that percolates soft-core, pseudographic whiskers in a discrete matrix has been developed, and two- and three-dimensional whisker percolation thresholds were determined for various whisker aspect ratios. The percolation thresholds were found to agree with the predictions of the excluded volume theory of percolation; moreover, the thresholds were found to coincide with the zero-shrinkage whisker fraction in ceramic matrix-ceramic particle composites.

scholarly journals Solid State NMR Spectroscopy a Valuable Technique for Structural Insights of Advanced Thin Film Materials: A Review

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1494
Author(s):  
Mustapha El Hariri El Nokab ◽  
Khaled O. Sebakhy
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solid State ◽  
Solid State Nmr ◽  
Pulse Sequences ◽  
3D Structure ◽  
Spectroscopic Techniques ◽  
Film Research ◽  
Versatile Technique ◽  
Work Done

Solid-state NMR has proven to be a versatile technique for studying the chemical structure, 3D structure and dynamics of all sorts of chemical compounds. In nanotechnology and particularly in thin films, the study of chemical modification, molecular packing, end chain motion, distance determination and solvent-matrix interactions is essential for controlling the final product properties and applications. Despite its atomic-level research capabilities and recent technical advancements, solid-state NMR is still lacking behind other spectroscopic techniques in the field of thin films due to the underestimation of NMR capabilities, availability, great variety of nuclei and pulse sequences, lack of sensitivity for quadrupole nuclei and time-consuming experiments. This article will comprehensively and critically review the work done by solid-state NMR on different types of thin films and the most advanced NMR strategies, which are beyond conventional, and the hardware design used to overcome the technical issues in thin-film research.

scholarly journals Stoichiometry control and electronic and transport properties of pyrochlore Bi2Ir2O7 thin films

2018 ◽  
Vol 2 (11) ◽  
Author(s):  
W. C. Yang ◽  
Y. T. Xie ◽  
X. Sun ◽  
X. H. Zhang ◽  
K. Park ◽  
...  
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Stoichiometry Control

scholarly journals Nanometer-Thick [(FPEA)2PbX4; X=I, Br] 2D Halide Perovskite Based Thin Films for Pollutant Detection and Nonconventional Photocatalytic Degradation

2021 ◽  
Author(s):  
Arindam Mondal ◽  
Akash Lata ◽  
Aarya Prabhakaran ◽  
Satyajit Gupta
Keyword(s):  
Thin Films ◽  
Photocatalytic Degradation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Reduced Dimensionality ◽  
P Application ◽  
Halide Perovskites ◽  
Halide Perovskite ◽  
Pollutant Detection

Application of three-dimensional (3D)-halide perovskites (HaP) in photocatalysis encourages the new exercise with two-dimensional (2D) HaP based thin-films for photocatalytic degradation of dye. The reduced dimensionality to 2D-HaPs, with a...

scholarly journals Three-Dimensional Printable Hydrogel Using a Hyaluronic Acid/Sodium Alginate Bio-Ink

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 794 ◽  
Author(s):  
Su Jeong Lee ◽  
Ji Min Seok ◽  
Jun Hee Lee ◽  
Jaejong Lee ◽  
Wan Doo Kim ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Hyaluronic Acid ◽  
Sodium Alginate ◽  
Three Dimensional ◽  
Fibroblast Cell ◽  
Chemical Crosslinking ◽  
Fibroblast Cell Line ◽  
Engineering Applications ◽  
Encapsulated Cells ◽  
Crosslinking Agents

Bio-ink properties have been extensively studied for use in the three-dimensional (3D) bio-printing process for tissue engineering applications. In this study, we developed a method to synthesize bio-ink using hyaluronic acid (HA) and sodium alginate (SA) without employing the chemical crosslinking agents of HA to 30% (w/v). Furthermore, we evaluated the properties of the obtained bio-inks to gauge their suitability in bio-printing, primarily focusing on their viscosity, printability, and shrinkage properties. Furthermore, the bio-ink encapsulating the cells (NIH3T3 fibroblast cell line) was characterized using a live/dead assay and WST-1 to assess the biocompatibility. It was inferred from the results that the blended hydrogel was successfully printed for all groups with viscosities of 883 Pa∙s (HA, 0% w/v), 1211 Pa∙s (HA, 10% w/v), and 1525 Pa∙s, (HA, 30% w/v) at a 0.1 s−1 shear rate. Their structures exhibited no significant shrinkage after CaCl2 crosslinking and maintained their integrity during the culture periods. The relative proliferation rate of the encapsulated cells in the HA/SA blended bio-ink was 70% higher than the SA-only bio-ink after the fourth day. These results suggest that the 3D printable HA/SA hydrogel could be used as the bio-ink for tissue engineering applications.

scholarly journals Fabrication, micro-structure characteristics and transport properties of co-evaporated thin films of Bi2Te3 on AlN coated stainless steel foils

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aziz Ahmed ◽  
Seungwoo Han
Keyword(s):  
Thin Film ◽  
Crystal Structure ◽  
Thin Films ◽  
Stainless Steel ◽  
Substrate Temperature ◽  
Transport Properties ◽  
Structural Defects ◽  
Film Composition ◽  
High Substrate ◽  
Foil Substrate

AbstractN-type bismuth telluride (Bi2Te3) thin films were prepared on an aluminum nitride (AlN)-coated stainless steel foil substrate to obtain optimal thermoelectric performance. The thermal co-evaporation method was adopted so that we could vary the thin film composition, enabling us to investigate the relationship between the film composition, microstructure, crystal preferred orientation and thermoelectric properties. The influence of the substrate temperature was also investigated by synthesizing two sets of thin film samples; in one set the substrate was kept at room temperature (RT) while in the other set the substrate was maintained at a high temperature, of 300 °C, during deposition. The samples deposited at RT were amorphous in the as-deposited state and therefore were annealed at 280 °C to promote crystallization and phase development. The electrical resistivity and Seebeck coefficient were measured and the results were interpreted. Both the transport properties and crystal structure were observed to be strongly affected by non-stoichiometry and the choice of substrate temperature. We observed columnar microstructures with hexagonal grains and a multi-oriented crystal structure for the thin films deposited at high substrate temperatures, whereas highly (00 l) textured thin films with columns consisting of in-plane layers were fabricated from the stoichiometric annealed thin film samples originally synthesized at RT. Special emphasis was placed on examining the nature of tellurium (Te) atom based structural defects and their influence on thin film properties. We report maximum power factor (PF) of 1.35 mW/m K2 for near-stoichiometric film deposited at high substrate temperature, which was the highest among all studied cases.

Submicron Patterned Anodic Oxidation of Aluminum Thin Films

2000 ◽  
Vol 636 ◽  
Author(s):  
Qiyu Huang ◽  
Whye-Kei Lye ◽  
David M. Longo ◽  
Michael L. Reed
Keyword(s):  
Thin Films ◽  
Anodic Oxidation ◽  
Ion Beam ◽  
Electrochemical Anodization ◽  
Optical Methods ◽  
Imprint Lithography ◽  
Aluminum Films ◽  
Aspect Ratios ◽  
Potential Applications ◽  
Nano Imprint

AbstractAlumina formed by the electrochemical anodization of bulk aluminum has a regular porous structure [1]. Sub-100 nm pores with aspect ratios as high as 1000:1 can easily be formed [2] without elaborate processing. Anodization of aluminum thus provides the basis for the inexpensive, high throughput microfabrication of structures with near vertical sidewalls [2]. In this work we explore the patterned anodic oxidation of deposited aluminum thin films, facilitating the integration of this technique with established microfabrication tools. An anodization barrier of polymethylmethacrylate (PMMA) is deposited onto 300 nm thick aluminum films. The barrier film is subsequently patterned and the exposed aluminum anodized in a 10% sulfuric acid solution. Barrier patterning techniques utilized in this study include optical exposure, ion-beam milling and nano-imprint lithography. Sharp edge definition on micron scale patterns has been achieved using optical methods. Extension of this technique to smaller dimensions by ion-beam milling and nano-imprint lithography is presented. We further report on the observation of contrast reversal of anodization with very thin PMMA barriers, which provides a novel means of pattern transfer. Potential applications and challenges will be discussed.

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