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Annealing before and after pellet formation

  1. Jun 8, 2006 #1
    In the case of nanoparticles is there any diffrence on the results (particle size and the other properties that are dependent on particle size) of two similer samples, one of which is annealed after pellet formation and the second sample is annealed in the powdered shape and then pellet is formed.Which way is more suitable practically?

    Thanks
     
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  3. Jun 8, 2006 #2

    Gokul43201

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    The optimized synthesis conditions are highly specific to the material being synthesized. Can you give us more details?
    1. What is the material (reactants, if involved, and final product)?
    2. What is the target particle-size range?
    3. What is the primary synthesis route (solid phase)?
    4. Is there an established procedure that you are aware of for this?
     
  4. Jun 8, 2006 #3
    I am preparing Ni-Zn Ferrites by chemical coprecipitation method, the intial reactents being the chlorides of Ni, Zn and Fe. For XRD you need powdered samples and particle size is determined from XRD, so one needs to anneal the samples in powdered form for XRD. Now in order to measure diffrent properties e.g resistivity etc you need pellet. If I take a powdered sample, divide it in two parts, anneal one part and determin the particle size from its XRD, make the pellet of the second part and then anneal it to determen diffrent properties then if it is fair to assume that these properties corresponds to the particle size determen by the first part of the sample?
    There is another way as well, to anneal the sample first and then make pellets for characterization, but it come out with its own problems e.g porosity etc. The particle size is within 7 to 20 nm.Can you give me an advice to counter that problem?
    Thanks.
     
  5. Jun 9, 2006 #4

    Gokul43201

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    Let me make sure I understand you correctly. First of all, annealing is not something that is required to do XRD on a powder sample. But the annealing temperature is probably what eventually determines the particle size. So you want to anneal the powder sample and then use it for XRD. Is that right?

    In theory, no. In practice, the difference may be small enough to neglect. It will depend on, among other things, the pressure applied during pelletizing. At high pressures (~ several MPa), there's a good chance that the particle size will be different.

    Here's a priliminary suggestion:

    What is the thinnest pellet you can make? Try it and figure that out. Meanwhile, find out from your XRD people if they can use a thin pellet instead of powder. It should be possible in most cases - lots of people have done XRD on sintered pellets.
     
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