Search results for "Surfaces and interfaces"
showing 10 items of 939 documents
Acoustic vibrations of metal nanoparticles: high order radial mode detection
2004
The vibrational radial modes of silver nanospheres embedded in a glass matrix are investigated using a high sensitivity femtosecond pump-probe technique. The results yield evidence for coherent launching of the fundamental and higher order radial modes in agreement with a sphere dilation mediated excitation model. The results are consistent with low-frequency Raman scattering experiments.
Relations between cavitation erosion resistance of materials and their fatigue strength under random loading
1999
Abstract The paper contains results of tests on fatigue strength under uniaxial random loading and cavitation erosion resistance for three steels: 10HNAP, 18G2A and 15G2ANb. The obtained fatigue and cavitation characteristics were used for determination of relations between these two phenomena. From the analysis it appears that there is correlation between fatigue strength of the material under random loading and its cavitation erosion resistance. It has been shown that fatigue tests under random loading and tests on cavitation erosion of 10HNAP, 18G2A and 15G2ANb steels may be described with a mathematical model of the same type. It has been also found that there is a linear relation, in t…
Probing the Conformational States of a pH-Sensitive DNA Origami Zipper via Label-Free Electrochemical Methods
2021
Funding Information: Financial support from EPSRC DTP (grant EP/R513349/1), the Emil Aaltonen Foundation, the Sigrid Jusélius Foundation, the Jane and Aatos Erkko Foundation, and the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters is gratefully acknowledged. This work was carried out under the Academy of Finland Centers of Excellence Programme (2014–2019). We acknowledge the provision of facilities and technical support by Aalto University Bioeconomy Facilities and OtaNano—Nanomicroscopy Center (Aalto-NMC) and Micronova Nanofabrication Center. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society DNA origami structures represe…
MOCVD deposition of YSZ on stainless steels
2003
Abstract Yttria stabilized zirconia was deposited on stainless steel using the metal–organic chemical vapor deposition (MOCVD) technique, from β-diketonate precursors. The variation of the evaporation temperatures of yttrium and zirconium precursor allowed to control the level of Y within the film. Over the temperature range 125–150 °C, the Y content increased from 2.5 to 17.6 at.%. X-ray diffraction (XRD) analyses evidenced tetragonal phase of zirconia when the Y content was below 8 at.%, and cubic phase for higher concentration. Sputtered neutral mass spectrometry (SNMS) profiles confirmed that the control and stability of Y precursor temperature were of major importance to guarantee the …
Mechanical properties of aluminum, zirconium, hafnium and tantalum oxides and their nanolaminates grown by atomic layer deposition
2015
ABSTRACT The mechanical properties of two different metal oxide nanolaminates comprised of Ta 2 O 5 and Al 2 O 3 , HfO 2 or ZrO 2 , grown on soda–lime glass substrate by atomic layer deposition, were investigated. Ta 2 O 5 and Al 2 O 3 layers were amorphous, whereas ZrO 2 and HfO 2 possessed crystalline structure. Thickness of single oxide layers was varied between 2.5 and 15 nm. The total thickness of the laminate structures was in the range of 160–170 nm. The hardness values of single layer oxides on glass ranged from 6.7 GPa (Ta 2 O 5 ) to 9.5 GPa (Al 2 O 3 ). Corresponding elastic moduli were 96 GPa and 101 GPa. The hardnesses of laminates were in the range of 6.8–7.8 GPa and elastic mo…
An empirical method to determine the free surface energy of solids at different deformations and temperatures regimes : An application to Al.
2005
Abstract We have performed molecular dynamics (MD) simulations using the three low index surfaces of Al to determine the variation of the surface energy as a function of deformation and temperature. We have also developed an empirical formulation for the surface free energy as a function of deformation. The observed difference between the numerical and analytical results has led us to divide the deformation into a mechanical and a thermal contribution. From this observation, we have obtained an expression for the surface free energy placing the temperature dependence on the bulk and surface elastic constants. Our simulations permitted us to analyze the multilayer relaxation for the particul…
Combined Temperature Radiation Effects and Influence of Drawing Conditions on Phosphorous‐Doped Optical Fibers
2018
International audience; This work focuses on the effects of high dose ionizing radiation, up to 10 MGy(SiO2), on P‐doped multimode optical fibers (OF) at different irradiation temperatures. The investigation is based on two complementary experimental techniques: radiation‐induced attenuation (RIA) measurements and electron paramagnetic resonance (EPR). The latter technique allows measuring the P1, P2, metastable‐POHC and stable‐POHC defects. Three OF samples are drawn from the same preform to evaluate the influence of changing their drawing conditions of the OFs on the radiation responses. This first study is performed under X‐rays at room temperature. The results are compared with the ones…
Porous architecture and thermal properties of thermal barrier coatings deposited by suspension plasma spray
2020
Abstract Besides the intrinsic low heat transfer capability of material, the thermal insulation property of thermal barrier coatings (TBCs) also relies on their microstructures. For better understanding the relationship between process parameters, porous architecture, and thermal properties of coatings, YSZ coatings were firstly manufactured by suspension plasma spray (SPS). Afterwards their total porosities were characterized by using the technique of X-ray transmission, the nano/submicro pores in those coatings were detected with Ultra-Small Angle X-ray Scattering (USAXS), and the thermal properties of coatings were measured using the laser flash method. The results indicated that: i) the…
Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment
2016
The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…
Carbon Dots Dispersed on Graphene/SiO2/Si: A Morphological Study
2019
Low-dimensional carbon materials occupy a relevant role in the field of nanotechnology. Herein, the authors report a study conducted by atomic force microscopy and Raman spectroscopy on the deposition of carbon dots onto graphene surfaces. The study aims at understanding if and how the morphology and the microstructure of chemical vapor deposited graphene on Si/SiO2 may change due to the interaction with the carbon dots. Potential alteration in the graphene's electrical properties might be detrimental for optoelectronic applications. The deposition of carbon dots dispersed in water and ethanol solvents are explored to investigate the effect of solvents with different fluidic properties. The…