Search results for "Material properties"
showing 10 items of 105 documents
Nano-inclusion suite and high resolution micro-computed-tomography of polycrystalline diamond (framesite) from Orapa, Botswana
2011
Abstract A single polycrystalline diamond aggregate from the Orapa kimberlite (Botswana) contains a syngenetic micro- and nano-inclusion suite of magnetite, pyrrhotite, omphacite, garnet, rutile and C–O–H fluid in order of abundance. This suite of inclusions is distinctly different from those in fibrous diamonds, although the presence of sub-micrometer fluid inclusions provides evidence for a similarly important role of fluids in the genesis of polycrystalline diamond. It is the first study of polycrystalline diamond by High resolution μ-CT (Computed Tomography) reaching a resolution of 1.3 μm using polychromatic X-rays. Combined with Focused Ion Beam assisted Transmission Electron Microsco…
Aerosol filtration efficiency of household materials for homemade face masks: Influence of material properties, particle size, particle electrical ch…
2020
As a consequence of the COVID-19 pandemic caused by the SARS-CoV-2 virus, the widespread daily use of face masks is promoted worldwide. Particle-size dependent filtration efficiencies (FE; dp = 30 nm–10 µm), applying a particle counting approach, and additionally pressure drops (Δp) were determined for 44 samples of household materials and several medical masks. Huge FE differences were found between sample materials and for different particle sizes, spanning from <10% up to almost 100%. Minimum FE were determined for dp = 50–500 nm particles with significantly larger values for dp = 30 nm particles and especially for those with dp > 2.5 µm. Measurements at different numbers of layers…
Effects of powder concentration and type of resin on the performance of marble composite structures
2009
In this work, we will expose the behaviour of a composite structure reinforced with marble powder. The attention was focused on the effects produced on the physical and mechanical properties due to different kinds of matrix (epoxy and polyester resins) and filler amounts (60%, 70%, 80%). Rheological, static flexural and Izod impact tests have been carried out. An experiment designed was defined for the mechanical tests, in order to quantify the effects of both the resin and the marble percentage on the material properties, as well as to identify a possible correlation between these factors. Moreover, water absorption and stain resistance have been evaluated to study the surface properties o…
Spin-resolved unoccupied density of states in epitaxial Heusler-alloy films
2009
We investigate the electronic properties of epitaxial ${\text{Co}}_{2}({\text{Fe}}_{x}{\text{Mn}}_{1\ensuremath{-}x})\text{Si}$, ${\text{Co}}_{2}\text{Fe}({\text{Al}}_{1\ensuremath{-}x}{\text{Si}}_{x})$, and ${\text{Co}}_{2}({\text{Cr}}_{0.6}{\text{Fe}}_{0.4})\text{Al}$ films on MgO(100) substrates using circular dichroism in x-ray absorption spectroscopy (XMCD). Considering final-state electron correlations, the spin-resolved partial density of states at the Co atom can be extracted from XMCD data. The experimental results corroborate the predicted half-metallic ferromagnetic properties of these alloys and reveal a compositional dependence of the Fermi energy position within the minority b…
Pumice concrete for structural wall panels
2003
Some properties of lightweight pumice stone concrete (LWPSC) are discussed, on account of a possible structural use of this material. Then the results of an experimental investigation are described, in order to show that pumice can really be considered an alternative to common artificial lightweight aggregates, taking into account the performance pointed out by loading tests carried out on structural systems made of LWPSC. Three different kinds of reinforced wall panels were made using LWPSC, lightweight expanded clay concrete and normal weight concrete; then their structural responses under horizontal cyclic and constant vertical forces were compared, above all with reference to lateral st…
Synthesis, characterization and magnetism of monodispersed water soluble palladium nanoparticles
2008
Water soluble, monodispersed Pd nanoparticles with a narrow particle size distribution have been successfully synthesized by controlled reduction of [PdCl4]2−. The resulting aqueous colloids are stable over extended periods of time and can be prepared at high nanoparticle loading (20 g/L of Pd) with no agglomeration. The size of the nanoparticles can be reduced from the nanometer (ca. 3.5 nm) to the sub-nanometer size range (ca. 0.9 nm). Detailed magnetic characterization indicated that the larger, 3.5 nm nanoparticles show ferromagnetic properties at room temperature, while the sub-nanometric ones lose this magnetic behavior.
Growth zoning and strain patterns inside diamond crystals as revealed by Raman maps
2005
The Raman mapping technique provides a non-destructive means of studying internal growth textures and other micro-structural heterogeneity inside diamond single-crystals. Raman maps showing distribution patterns of the bandwidth (FWHM) of the main first-order lattice vibration of diamond ( LO=TO phonon at ~1332 cm −1 ) along two-dimensional planes inside diamond crystals may reveal the internal growth zoning of these crystals. The observed zoning is affected, and in some cases even obscured in micro-areas adjacent to inclusions, by patterns of heterogeneous strain in the diamond. We present Raman maps obtained from diamond crystals containing large, single-crystal graphite inclusions, from …
Influence of thickness and interface on the low-temperature enhancement of the spin Seebeck effect in YIG films
2016
The temperature-dependent longitudinal spin Seebeck effect (LSSE) in heavy metal (HM)/Y_{3}Fe_{5}O_{12} (YIG) hybrid structures is investigated as a function of YIG film thickness, magnetic field strength, and different HM detection materials. The LSSE signal shows a large enhancement with reductions in temperature, leading to a pronounced peak at low temperatures. We find that the LSSE peak temperature strongly depends on the film thickness as well as on the magnetic field. Our result can be well explained in the framework of magnon-driven LSSE by taking into account the temperature-dependent effective propagation length of thermally excited magnons in the bulk of the material. We further …
Magnetic and magneto-optical properties of nickel hexacyanoferrate/chromate thin films
2017
One of the most important challenges of modern science and technology is the quest for novel and tuneable materials, the properties of which can be widely controlled by chemical modifications or external stimuli. Simultaneously, an interest in the development of magnetic thin films also gains significant attention. In the current paper we bring together both these challenges and present a study of a new type of low-dimensional nickel hexacyanoferrate/chromate system. Thin films were obtained by the "layer by layer" deposition technique, where the ratio of Fe/Cr was controlled by the dipping sequence. The scope of this work is a comprehensive analysis of structural, spectroscopic and magneti…
Seed layer technique for high quality epitaxial manganite films
2016
We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening tempera…