Search results for "surface energy"
showing 10 items of 97 documents
ZnWO4 nanocrystals: synthesis, morphology, photoluminescence and photocatalytic properties
2018
The present joint experimental and theoretical work provides in-depth understanding on the morphology and structural, electronic, and optical properties of ZnWO4 nanocrystals. Monoclinic ZnWO4 nanocrystals were prepared at three different temperatures (140, 150, and 160 °C) by a microwave hydrothermal method. Then, the samples were investigated by X-ray diffraction with Rietveld refinement analysis, field-emission scanning electron microscopy, transmission electronic microscopy, micro-Raman and Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence measurements. First-principles theoretical calculations within the framework of density functional the…
Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene
2012
Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide ( [Formula: see text] , [Formula: see text…
Wettability of MXene and its interfacial adhesion with epoxy resin
2021
Abstract The surface energies of MXene nanofillers critically affect the mechanical properties and durability of any polymer-based devices and composites to which these fillers are applied. In this context, this study comprehensively investigates Ti3C2Tz MXenes prepared via the hydrochloric acid/lithium fluoride etching of Ti3AlC2. The surface energy values of 10-layer MXene coatings were evaluated to be between 47.98 and 64.48 mJ/m2 as per contact-angle measurements. The wettability properties were found to depend on the number of coating layers and the liquids used. Additionally, the coating roughness was evaluated by using atomic force microscopy. The effectiveness of MXenes as a reinfor…
Programmable Surface Architectures Derived from Hybrid Polyoxometalate-Based Clusters
2011
The exploration of the self-organization of a range of the polyoxometalate-based molecular structures reveals a diverse range of surface patterns and morphologies on solid substrates of technological interest, including methylated and hydroxylated silicon surfaces (namely, SiCH3 and SiOH). By exploiting the interplay between the intrinsic molecular properties and the surface chemistry as well as dynamic spatiotemporal phenomena (e.g., dewetting), we show that these systems can yield 0D, 2D, and 3D architectures via solution deposition at the solid surface, including nanodots, discs, lamellas, porous networks, and layer-by-layer assemblies. In general, we observed that layer-by-layer growth …
Study of silicon crystal surface formation based on molecular dynamics simulation results
2014
Abstract The equilibrium shape of 〈 110 〉 -oriented single crystal silicon nanowire, 8 nm in cross-section, was found from molecular dynamics simulations using LAMMPS molecular dynamics package. The calculated shape agrees well to the shape predicted from experimental observations of nanocavities in silicon crystals. By parametrization of the shape and scaling to a known value of { 111 } surface energy, Wulff form for solid-vapor interface was obtained. The Wulff form for solid–liquid interface was constructed using the same model of the shape as for the solid–vapor interface. The parameters describing solid–liquid interface shape were found using values of surface energies in low-index dir…
Supramolecular Order of Solution-Processed Perylenediimide Thin Films
2011
N,N ′ -1 H ,1 H -perfl uorobutyl dicyanoperylenecarboxydiimide (PDIF-CN 2 ), a soluble and air stable n-type molecule, undergoes signifi cant reorganization upon thermal annealing after solution deposition on several substrates with different surface energies. Interestingly, this system exhibits an exceptional edge-on orientation regardless of the substrate chemistry. This preferential orientation is rationalized in terms of strong intermolecular interactions between the PDIF-CN 2 molecules. The presence of a pronounced π– π stacking is confi rmed by combining near-edge X-ray absorption fi ne structure spectroscopy (NEXAFS), dynamic scanning force microscopy (SFM) and surface energy measure…
Interfacial energy effects within the framework of strain gradient plasticity
2009
AbstractIn the framework of strain gradient plasticity, a solid body with boundary surface playing the role of a dissipative boundary layer endowed with surface tension and surface energy, is addressed. Using the so-called residual-based gradient plasticity theory, the state equations and the higher order boundary conditions are derived quite naturally for both the bulk material and the boundary layer. A phenomenological constitutive model is envisioned, in which the bulk material and the boundary layer obey (rate independent associative) coupled plasticity evolution laws, with kinematic hardening laws of differential nature for the bulk material, but of nondifferential nature for the layer…
Photon assisted-inversion of majority charge carriers in molecular semiconductor-based organic heterojunctions
2021
International audience; Ambipolar molecular materials hold great promises as a building block of next generation highly efficient, less complex and low cost electronics devices. In this endeavor, the present work reports the fabrication of organic heterojunction devices based on halogenated copper Phthalocyanines (CuPc) and lutetium bisphthalocyanine (LuPc2) bilayer, investigates their structural and electrical properties and probes the ambipolar behavior by ammonia sensing. Microstructural analysis of the heterostructure thin films revealed compact and semicrystalline organization, depending on the number of halogen substituents in CuPc. The heterojunction devices reveal a non-linear I(V) …
A critical analysis of three remote sensing-based actual evapotranspiration assessment methods over sparse crops agricultural areas
2010
During last two decades the increasing availability of remotely sensed acquisitions in the thermal infrared part of the spectrum has encouraged hydrologist community to develop models and methodologies based on these kind of data. The aim of this paper is to compare three methods developed to assess the actual evapotranspiration spatial distribution by means of remote sensing data. The comparison was focused on the differences between the "single" (SEBAL) and "two" source (TSEB) surface energy balance approaches and the S-SEBI semi-empirical method. The first assumes a semiempirical internal calibration for the sensible heat flux assessment; the second uses a physically based approach in or…
Fukushima, or the Black Swan of Nuclear Energy
2012
By its own merits, the great earthquake that hit Japan on 11 March 2011 would have qualified as one of the worse disasters of recent times. With a magnitude of 9.0 MW, it was the most powerful known earthquake ever to have hit Japan, and one of the most powerful in history. It released a surface energy 2 × 1017 Joule. Enough, if harnessed, to power a city the size of Los Angeles for an entire year.