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Heat Capacity of Nanoparticles - Experimental Determination

  1. Dec 10, 2014 #1

    acb

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    I know little about the experimental measurements of heat capacity. I can see you'd need to know both how much energy you've transferred to a nanoparticle, and measure the temperature change resulting to ascertain it. This brings me to my questions:

    How effective is laser heating of nanoparticles for determining heat capacity?
    How is temperature of the nanoparticle measured? An infra-red thermometer like device?

    I'm guessing the answers are "Not very", and "No", because otherwise many mysteries in materials science would have already been solved. To reframe my question:

    Would someone like to tell me about the difficulties of measuring heat capacities in nanoparticles?
     
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  3. Dec 10, 2014 #2

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    What makes you think there's any more difficulty to measurement of heat capacity of nanoparticles than there is of any other material?
     
  4. Dec 10, 2014 #3

    acb

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    A few reasons:

    1) It's very small, and so insulating it might be difficult while also keeping it from aggregating with something else.
    2) This is a very important topic. I know that in hydrogen storage, for example, people would very much like to know the heat capacity of nanoparticles they attempt to hydride, as that would allow them to separate the components of a (hydrogen) desorption reaction free energy. That is, if say: metal-hydride -> hydrogen + metal, then you're very interested in what the heat capacity of the metal is vs. the metal-hydride, as that will dominate the thermodynamics. Medical applications seem abundant for nanoparticles also. Basically this point summarised is: "If it's so important, where are the numbers?"
    3) Back to (1) - how do you measure the temperature of a nanoparticle? Measuring its emitted radiation might work, but then how do you heat it (a laser would surely mess with that reading)? Then if you try heating it an insulator, via convection (like in an oven), how do you keep it from reacting with its container? It seems like there would be temperatures beyond which the entire exercise was fraught with difficulty.

    I really don't know though. Is it harder?
     
  5. Dec 10, 2014 #4

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    Heat capacities are commonly measured calorimetrically, X moles (or mass) of material are raised from an initial T to a final T and necessary heat measured, or measured heat is applied and temperature difference is measured. Single atom/molecule heat capacities can be determined spectroscopically, but I don't think I'd try it for nanoparticles.
     
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