Search results for "ALLOYS"
showing 10 items of 1689 documents
Organic-nanoclay composite materials as removal agents for environmental decontamination
2019
Here we overview the recent advances in the fabrication of sustainable composite nanomaterials with decontamination capacity towards inorganic and organic pollutants. In this regards, we present the development of hybrid systems based on clay nanoparticles with different shapes (such as kaolinite nanosheets and halloysite nanotubes) and organic molecules (biopolymers, surfactants, cucurbituril) as efficient removal agents for both aliphatic and aromatic hydrocarbons. Due to their high specific surface area, clay nanoparticles have been successfully employed as fillers for composite membranes with excellent filtration capacity. The preparation of composite gel beads based on biopolymers (alg…
Alginate gel beads filled with halloysite nanotubes
2013
Abstract Novel hybrid gel beads with a well defined and controlled size formed by alginate biopolymer and halloysite (Hal) nanotubes were designed, prepared and characterized from the physico-chemical viewpoint. The thermogravimetry made it possible to determine the water content, the total as well as the local compositions of Hal into the gel beads. Dielectric spectroscopy evidenced that Hal reduced the fluctuation of ions. The SEM micrographs showed that the dried beads exhibit a rough surface, with pores in the micrometer range. In addition, the concentration of nanotubes was higher into the bead core at a higher overall loading. The performance of these materials was verified with the s…
Upconversion luminescence in transparent oxyfluoride glass ceramics containing hexagonal NaErF4
2019
The authors wish to express gratitude to K. Smits for TEM measurements. This research is funded by the Latvian Council of Science, project “Novel transparent nanocomposite oxyfluoride materials for optical applications”, project No. LZP-2018/1-0335. GK wishes to expresses gratitude to Arnis Riekstins "MikroTik" donation. Donations are administered by the University of Latvia Foundation. © 2019. This work is licensed under a CC BY-NC-ND 4.0 license.
Evidence of hexagonal WO3 structure stabilization on mica substrate
2009
International audience; WO3 nanorods are grown by a simple vapor deposition method on a mica substrate and characterized by Selected Area Electron Diffraction and Energy Dispersive X-rays Spectroscopy. Experimental results show the clear evidence of an unexpected WO3 hexagonal structure as well as an epitaxial growth on the mica substrate. Besides, potassium is evidenced inside the nanorods. It is thus deduced that a metastable WO3 hexagonal phase is stabilized by epitaxy through a tungsten bronze interlayer having same hexagonal structure.
Synthesis and characterization of nanomaterial based on halloysite and hectorite clay minerals covalently bridged
2021
Halloysite is an aluminosilicate clay with a predominantly hollow tubular structure (HNTs) able to act as a nanocontainer for the encapsulation of several chemicals. However, HNTs possess low affinity for metal ions in their pristine form and they need to be modified for improving their adsorption capabilities. Therefore, to overcome this issue herein we report a straightforward approach for the covalent modification of the external surface of halloysite nanotubes with hectorite clay. Compared to halloysite, hectorite possesses a lamellar structure with higher cation exchange capacity. The covalent linkage between the two clays was verified by several techniques (FTIR spectroscopy, 13C CP-M…
Optimisation of metallic interconnects for hydrogen production by high temperature water vapour electrolysis
2012
For economical and environmental reasons, hydrogen is considered as a major energetic vector for the future. Hydrogen production via high temperature water vapour electrolysis (HTE) is a promising technology. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800°C enables the use of metallic materials as interconnects. Chromia forming alloys are among the best candidates. The interconnect material chosen in the present study is a ferritic stainless steel with 18% chromium content. High temperature corrosion resistance and electrical conductivity of the alloy was…
Whispering gallery mode resonator and glucose oxidase based glucose biosensor
2020
Abstract In this research whispering gallery mode resonators (WGMRs) were applied in new concept of glucose sensor based on the shift of WGM resonance frequency induced by enzymatic oxidation of glucose by glucose oxidase (GOx), which was immobilized on WGM-resonator surface. During the enzymatic reaction catalyzed by GOx electrons from glucose via GOx are transferred towards co-immobilized gold nanoparticles (Au-NPs). WGM-resonators were fabricated from standard telecommunication optical-fiber melted in a hydrogen flame. Whispering gallery mode resonance based optical signals generated by these WGM-resonators were evaluated. These WGM-resonators, which were characterized by sufficient qual…
Effects of ball-milling on the hydrogen sorption properties of LaNi5
2009
Abstract Pressure–composition isotherms of LaNi 5 alloys were studied as function of ball-milling time. Results indicate that ball-milling convert a part of the LaNi 5 to a non-absorbing state—a state which does not absorb hydrogen under conditions where un-milled LaNi 5 powders absorb and transform to LaNi 5 H 6 , in addition to particle size reduction and creation of defects. The non-absorbing fraction in the milled sample is found to grow with increase in the ball-milling time. The resistance to the hydride formation of the long-time ball-milled LaNi 5 samples is found to continue even after a 1-h high vacuum annealing at around 1000 K. This indicates that the hydrogen-absorption-resist-…
Modeling of the hydrogen sorption kinetics in an AB2 laves type metal hydride alloy
2021
Abstract Hydrides of the AB2 Laves type alloys (A=Zr, Ti; B = transition metal – Fe, Co, Ni, Mn, Cr, V) have been extensively studied as materials for the storage of gaseous hydrogen. They contain up to 4 H atoms/formula unit AB2, thus achieving reversible H storage capacities in the range between 1.5 and 2.0 wt% H and offering high rates of hydrogen charge and discharge, thus making them suitable for designing efficient hydrogen stores operating at ambient conditions. In the present study, we performed an experimental study and modeling of the thermodynamics and the kinetics of interaction in the AB2-hydrogen system. The experimental data was collected by studying a model alloy with a comp…
Photo-switching and -cyclisation of hydrogen bonded liquid crystals based on resveratrol
2020
A series of hydrogen-bonded liquid crystals based on resveratrol and resveratrone is reported and investigated with respect to their photo-switchability (at 405 nm) and photo-cyclisation (at 300 nm).