Search results for "sublimation"
showing 10 items of 38 documents
Methods for Enhancing the Thermal Durability of High-Temperature Thermoelectric Materials
2013
Author's version of an article in the journal: Journal of Electronic Materials. Also available from the publisher at: http://dx.doi.org/10.1007/s11664-013-2917-0 Thermoelectric materials, for example skutterudites and magnesium silicides, are being investigated as promising materials for medium-to-high-temperature waste heat recovery in transport and in industry. A crucial aspect of the success of a thermoelectric material is its stability over time when exposed to rapid heating and cooling. In this work different aspects of the degradation of these thermoelectric materials at high temperature were examined. Initial thermal durability was studied, and several candidate coatings were evaluat…
Contrail Formation: Analysis of Sublimation Mechanisms
2018
We study losses of ice crystals in a persistent, soot-rich contra i l in the wake behind a medium-sized aircraft at cru i se. Constrain i n g a model covering ice nucleation, growth, and subl i m a t i o n phases with a n aircraft data set, we track the subl i m a t i o n history over two minutes of cont r a i l age and rela t e ice crystal numbers to the number of soot particles emitted by th e aircraft engines.
Synthesis, Characterization, Thermal and Antimicrobial studies of N-substituted Sulfanilamide derivatives
2014
Abstract Four sulfanilamide derivatives N -[4-(phenylsulfamoyl)phenyl]acetamide (1), 4-amino- N -phenylbenzenesulfonamide (2), N -[4-(phenylsulfamoyl)phenyl]benzamide (3) and N -{4-[(3-chlorophenyl)sulfamoyl]phenylbenzamide (4) were synthesized and characterized by Infra-Red (IR), Nuclear Magnetic Resonance (NMR) and UV–visible (UV–Vis) spectra. Also Liquid Chromatographic (LCMS) and High Resolution Mass Spectrometric (HRMS) methods were used. Crystal structures of 1–4 were determined by single crystal X-ray diffraction (XRD) and their conformational and hydrogen bond (HB) network properties were examined with survey of the literature data. Compounds 1 and 2 crystallize in the same orthorho…
Susceptibility of contrail ice crystal numbers to aircraft soot particle emissions
2017
We develop an idealized, physically-based model describing combined effects of ice nucleation and sublimation on ice crystal number during persistent contrail formation. Our study represents the first effort to predict ice numbers at the point where contrails transition into contrail cirrus—several minutes past formation—by connecting them to aircraft soot particle emissions and atmospheric supersaturation with respect to ice. Results averaged over an observed exponential distribution of ice supersaturation (mean value 15%) indicate that large reductions in soot particle numbers are needed to lower contrail ice crystal numbers significantly for soot emission indices around 1015 (kg-fuel)−1,…
Efficient Wide-Bandgap Mixed-Cation and Mixed-Halide Perovskite Solar Cells by Vacuum Deposition
2021
Vacuum deposition methods are increasingly applied to the preparation of perovskite films and devices, in view of the possibility to prepare multilayer structures at low temperature. Vacuum-deposited, wide-bandgap solar cells based on mixed-cation and mixed-anion perovskites have been scarcely reported, due to the challenges associated with the multiple-source processing of perovskite thin films. In this work, we describe a four-source vacuum deposition process to prepare wide-bandgap perovskites of the type FA1-n Cs n Pb(I1-x Br x )3 with a tunable bandgap and controlled morphology, using FAI, CsI, PbI2, and PbBr2 as the precursors. The simultaneous sublimation of PbI2 and PbBr2 allows the…
In Situ Observations of Ice Particle Losses in a Young Persistent Contrail
2018
We describe results of in situ observations of a 1 to 2-min old contrail in the vortex Phase generated from soot-rich exhaust (> 10^15 emitted soot particles per kg-fuel burned). Simultaneous measurements of soot (EIsoot) and apparent ice (AEIice) particle number emission indices show a pronounced anti-correlation in the vertical contrail profile. AEIice decrease by about 75% with increasing distance below the contrail-producing aircraft,while EIsoot increase by an equivalent relative fraction, therefore strongly suggesting sublimation causing the ice particle losses. Quantifying these losses in measurements helps to validate and improve contrail parameterizations used to estimate the clima…
The functionalization of nanodiamonds (diamondoids) as a key parameter of their easily controlled self-assembly in micro- and nanocrystals from the v…
2014
We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation …
Intercomparison of volcanic gas monitoring methodologies performed on Vulcano Island, Italy
2004
[1] Volcanic gas emissions from fumaroles on the rim of La Fossa crater, Vulcano Island, Italy, were measured simultaneously using direct sampling (for H2O, CO2, total sulfur, HCl and HF), filter packs (for SO2, HCl, HF) and short-path active-mode FTIR measurements (for H2O, CO2, SO2, HCl and HF) in an intercomparison study in May 2002. The results show that Cl/F ratios were in good agreement between all three methods, and that FTIR and direct sampling determined comparable proportions of CO2 and H2O. Amounts of total S observed in direct sampling data were approximately double the amounts of SO2 measured with filter packs and FTIR. This difference could be attributed either to the fact FTI…
An epitaxial hexagonal tungsten bronze as precursor for WO3 nanorods on mica.
2008
International audience; Tungsten oxide nanorods are grown at atmospheric pressure and low temperature (360 1C), by sublimation of WO3 and condensation on mica substrates. The nanorods are characterized by atomic force microscopy, high-resolution electron microscopy, energy-dispersive X-ray spectroscopy and high energy electron diffraction. The experimental results evidence the formation of a hexagonal tungsten bronze at the nanorod–substrate interface. The epitaxial relationships of the nanorods on mica are determined and the role of epitaxial orientation of the interfacial bronze in the nanorod growth and morphology are discussed.
Deposition Kinetics and Compositional Control of Vacuum-Processed CH3NH3PbI3 Perovskite
2020
Halide perovskites have generated considerable research interest due to their excellent optoelectronic properties in the past decade. To ensure the formation of high-quality semiconductors, the deposition process for the perovskite film is a critical issue. Vacuum-based processing is considered to be a promising method, allowing, in principle, for uniform deposition on a large area. One of the benefits of vacuum processing is the control over the film composition through the use of quartz crystal microbalances (QCMs) that monitor the rates of the components in situ. In metal halide perovskites, however, one frequently employed component or precursor, CH3NH3I, exhibits nonstandard sublimatio…