| 1. |
- Granqvist, Claes-Göran, et al.
(författare)
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Chromogenics for Sustainable Energy : Some Advances in Thermochromics and Electrochromics
- 2010
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Ingår i: Advances in Science and Technology. - 1662-0356. ; 75, s. 55-64
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Tidskriftsartikel (refereegranskat)abstract
- Chromogenic materials are able to change their optical properties in response to external stimuli such as temperature (in thermochromic materials) and electrical charge insertion (in electrochromic materials). Below we review some recent advances for these types of materials. Specifically we first discuss the limitations of thermochromic VO2 films for energy efficient fenestration and show from calculations that nanocomposites containing VO2 can have superior properties and display high luminous transmittance and large temperature-dependent solar transmittance modulation. Even better results may be found for nanoparticles of VO2:Mg. In the second part of the paper we survey some recent progress for electrochromic devices and show that W oxide films have increased coloration efficiency when some Ni oxide is added. We also present initial results for flexible electrochromic foils produced by roll-to-roll coating and continuous lamination.
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| 2. |
- Lansåker, Pia C., et al.
(författare)
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Au-Based Transparent Conductors for Window Applications : Effect of Substrate Material
- 2010
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Ingår i: Advances in Science and Technology. - 1662-0356. ; 75, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of Au were made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films were up to ~11 nm in thickness and covered the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less “holey” film. Scanning electron microscopy and atomic force microscopy showed that the SnO2:In films were considerably rougher than the glass itself. This roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and electrical resistance could be reconciled with impeded Au film formation on the SnO2:In layer, leading to pronounced “plateaus” in the near infrared optical properties for Au films on SnO2:In and an accompanying change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses.
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| 3. |
- Persson, Nils-Krister
(författare)
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Textile as Artificial Nature - From Synthetic Sea Grass to Fibrous Implants
- 2017
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Ingår i: Advances in Science and Technology. - 1662-0356. ; 100, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- We develop the hypothesis that textile and nature have much in common and that in a time of biomimetics textile is a unique class of material that provides a bridge between artefacts, by definition synthetic, and biofacts - material entities found in and produced by nature, i.e. non-synthetic. Furthermore we formulate the (seemingly) contradictorily concept of Artificial Nature. Biomimetics sometimes emphasize the inspirational aspects so that science and technology get input from biology for new technological development for new artefacts. Artificial Nature instead emphasizes the other way around; adding sound, ecology based, technology to nature and in nature for enhancing ecosystem functions.Some characteristics of natural biofact materials and structures include pliability, softness, porosity, light weight, recyclability, and periodicity. Textiles are soft, foldable, of low weight, inherent porous, anisotropic as well as periodic, easily compatible with biodegradability and recyclability. Thus there are many similarities. These are discussed together with a number of cases where textiles are mimicking biofacts. We first look at synthetic see grass (Zostera marina) for remediation of one of the most important biotopes in the world where we show that textile processing techniques are able to make production efficient. Then we look at artificial leaves, i.e. photon collecting flexible patches and indicate the textile realization of such. One of the most valuable ecosystem services is the provision of clean water and maintaining a low degree of pollution in water is of outmost importance. Textile based water purification systems has been constructed and merged with fungus (Zygomycetes) we show the potential for enhancing wet land capability.
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| 4. |
- Prikhna, Tetiana, et al.
(författare)
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The effect of oxygen distribution inhomogeneity and presence of higher borides on the critical current density improvement of nanostructural MgB2
- 2010
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Ingår i: Advances in Science and Technology. - 1662-0356. ; 75, s. 161-166
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Tidskriftsartikel (refereegranskat)abstract
- MgB2-based nanostructural materials with rather high oxygen concentration (5-14 wt.%) and dispersed grains of higher borides (MgB12, MgB7) high-pressure (2 GPa or 30 MPa) synthesized (in-situ) or sintered (ex-situ) demonstrated high superconducting characteristics (critical current density, jc, up to 1.8-1.0106 A/cm2 in the self magnetic field and 103 in 8 T field at 20 K, 3-1.5105 A/cm2 in the self field at 35 K, upper critical field up to HC2 = 15 T at 22 K, field of irreversibility Hirr =13 T at 20 K). The additives (Ti, SiC) and synthesis or sintering temperature can affect the segregation of oxygen and formation of oxygen-enriched Mg-B-O inclusions in the material structure, thus reducing the amount of oxygen in the material matrix as well as the formation of higher borides grains, which affects an increase of the critical current density. The record high HC2 and Hirr have been registered for the material high-pressure (2 GPa) synthesized from Mg and B at 600 oC having 17% porosity and more than 7 wt.% of oxygen. The attained values of the critical current, AC losses and thermal conductivity make the materials promising for application for fault current limiters and electromotors. The structural and superconducting (SC) characteristics of the material with matrix close to MgB12 in stoichiometry has been studied and the SC transition Tc=37 K as well as jc= 5×104 A/cm2 at 20 K in the self field were registered, its Raman spectrum demonstrated metal-like behavior.
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| 5. |
- Wiklund, Urban, et al.
(författare)
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Development of monolayered low friction PVD ceramic coatings for application on tools and mechanical components
- 2006
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Ingår i: Advances in Science and Technology. - : Trans Tech Publications, Switzerland. - 1662-0356. ; 45, s. 122-131
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Ceramic carbon based coatings have become common on tools and machine components, mainly because they offer a greatly reduced friction, as compared to uncoated steel contacts, in combination with a considerable wear protection. Very often they contain alloying elements such as different metals to control properties like hardness, wear resistance and lubricity. Applied to component surfaces, also properties relating to the running-in behaviour become important since an efficient running-in is crucial for their long term steady-state functionality. Also, even though component coatings are meant to provide low friction in dry sliding, they are increasingly used also in lubricated situations. This raises demands for compatibility with common lubricants. All these aspects have to be considered when developing new tribological coatings and some of these are addressed in this work. Results from different sliding tests with coated and uncoated surfaces in both dry and boundary lubricated contacts are presented. The generated tribofilms and their influence on the tribological properties are compared for the different sliding conditions. It is also shown how lubricants and their additives can affect the running-in, the tribofilm formation, and alter the steady state friction.
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