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  • #344855

    Anonymous

    Microscopic metallic cubes could unleash the enormous potential of metamaterials to absorb light, leading to more efficient and cost-effective large-area absorbers for sensors or solar cells, Duke University researchers have found.
    Metamaterials are human-made materials that have properties often absent in natural materials. They are constructed to provide exquisite control over the properties of waves, such as light. Creating these materials for visible light is still a technological challenge that has traditionally been achieved by lithography, in which metallic patterns are etched onto an inert material, much like an ink-jet printer.
    As effective as lithography has been in creating such structures, it does have a limitation — it is very expensive and thus difficult to scale up to the large surface areas required for many applications.
    "Our new approach is more of a bottom-up process," said Cristian Ciracì, research scientist at Duke's Pratt School of Engineering. "It may allow us to create devices — such as efficient solar panels — that cover much larger areas. In our experiments, we demonstrated an extraordinarily simple method to achieve this."
    The results of Ciracì and co-workers' experiments, which were conducted in the laboratory of senior researcher David R. Smith, William Bevan Professor of electrical and computer engineering at Duke, were published Dec. 6 in the journal Nature.
    For many applications or devices, the key is the material's ability to control the absorption of electromagnetic waves. Metals, for example, can be highly reflective on their own, which may be beneficial for some applications, but for something like a solar cell, optimal light absorption is desired.
    "However, metamaterials based on metallic elements are particularly efficient as absorbers because both the electrical and magnetic properties of the material can be controlled by how we design them," Ciracì said.
    The new metamaterial developed by the Duke team has three major components — a thin layer of gold film coated with a nano-thin layer of an insulator, topped off with a dusting of millions of self-assembled nanocubes. In the current experiments, the nanocubes were fabricated out of silver.
    "The nanocubes are literally scattered on the gold film and we can control the properties of the material by varying the geometry of the construct," Ciracì said. "The absorptivity of large surface areas can now be controlled using this method at scales out of reach of lithography."
    While metals on their own tend to have reflective properties, the nanocubes act as tiny antennae that can cancel out the reflectance of the metal surface.S
    "By combining different components of the metamaterial elements together into a single composite, more complicated reflectance spectra could be engineered, achieving a level of control needed in more exotic applications, such as dynamic inks," Ciracì said.

    source: http://www.sciencedaily.com/releases/2012/12/121206153644.htm

    #406677

    Anonymous

    Anything to get us off of middle east oil.  Sick of having to kiss the rear ends of jihad exporting Saudis

    #406678

    Anonymous
    Quote:
    Anything to get us off of middle east oil.  Sick of having to kiss the rear ends of jihad exporting Saudis

    Spot on

    #406679

    Anonymous

    Related but not on-topic. How strong could, read; if even is, be possibility for effective harrness of star light during clear nights?

    #406680

    Anonymous
    Quote:
    Related but not on-topic. How strong could, read; if even is, be possibility for effective harrness of star light during clear nights?

    I think that utilising the heat of the ground (not geothermal, but only ground warmth due to sunlight) would be more effective than that. The performance of photovoltaic (light) cells drops significantly even in a cloudy day.

    So answering your question: None.

    #406681

    Anonymous
    Quote:
    Related but not on-topic. How strong could, read; if even is, be possibility for effective harrness of star light during clear nights?

    tqr is right. However maybe we can gather comsic ray energy. Sun is going to its "darker" period soon and if cosmic rays don't destroy us maybe we can build some kind of machine that would gather the energy they possess  ;D

    #406682

    Anonymous
    Quote:
    I think that utilising the heat of the ground (not geothermal, but only ground warmth due to sunlight) would be more effective than that. The performance of photovoltaic (light) cells drops significantly even in a cloudy day.
    Quote:
    tqr is right. However maybe we can gather comsic ray energy. Sun is going to its "darker" period soon and if cosmic rays don't destroy us maybe we can build some kind of machine that would gather the energy they possess  ;D

    Yes naturally. :D I only asked from pure curiosity. Btw this heat off the ground as i understood it already exists. One of my realtives has something like that. Is this ground heater (?);

    [img width=700 height=468]http://www.vct-doo.si/upload/iblock/d74/objekt-mlinaric-kit-ljutomer%20015.jpg” />

    image

    image

    #406683

    Anonymous
    Quote:
    (…) Sun is going to its "darker" period soon and if cosmic rays don't destroy us maybe we can build some kind of machine that would gather the energy they possess  ;D

    WTF? Sun will be brighter and brighter all the time, until it will probably swallow Earth.

    Quote:
    Yes naturally. :D I only asked from pure curiosity. Btw this heat off the ground as i understood it already exists. One of my realtives has something like that. Is this ground heater (?);

    Yes, I've heard about it too. But I've meant the heat of ground after day (warmed by the Sun).

    Besides, the text is in Slovenian? I'm really becoming more and more convinced that your language is even funnier than Czech :P (dovodni/odvodni vodnjak, toplotna črpalka, lol)

    #406684

    Anonymous
    Quote:
    WTF? Sun will be brighter and brighter all the time, until it will probably swallow Earth.

    Yes, stars turns into red giant afterwards some of them it "blow up" forming supernova or neutron stars, other scenario is that red giant will release corona until it shrinks into white dwarf and in the end black dwarf(Sun's scenario most likely). Unrelated to this but Sun's protective bubble – helioshpere is shrinking as we talk giving us more "joy" of the cosmic rays.
    The reason why I placed "darker" because 2012/2013/2014 is Solar maximum, with many Solar flares so it shines energy of "darker" brightness/specter, but don't take my word for granted I'm not really specialist for this, I talk only what I read.

    #406685

    Anonymous
    Quote:
    The reason why I placed "darker" because 2012/2013/2014 is Solar maximum, with many Solar flares so it shines energy of "darker" brightness/specter, but don't take my word for granted I'm not really specialist for this, I talk only what I read.

    I don't think the energy input will be much lower, the cells' input are the photons, and in these "hidden ranges" the Sun also emits energy as photons :)

    But I'm not specialist either.

    #406686

    Anonymous
    Quote:
    Besides, the text is in Slovenian? I'm really becoming more and more convinced that your language is even funnier than Czech :P (dovodni/odvodni vodnjak, toplotna črpalka, lol)

    Well what can i say? What kind of words did you expect then? :D Vodnjak is water well. Odvodni and Dovodni should be logical imo. Or maybe not. ;D

    #406687

    Anonymous
    Quote:
    I don't think the energy input will be much lower, the cells' input are the photons, and in these "hidden ranges" the Sun also emits energy as photons :)

    But I'm not specialist either.

    But I never said it emits less energy, just of different specter, thought I believed that wavelength frequency matters as well

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