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Homework Help: Please ,Can some body help me ?

  1. Sep 17, 2006 #1
    Please ,Can some body help me ??

    hello members,

    I have some question ..... I need some body help me to solve them in solid state physics.....

    1) Given that the primitive basis vectors of a lattice are a=(a/2)(i+j),b=(a/2)(j+k),and c=(a/2)(k+i),where i,jand k are the usual three unit vectors along cartesian coordinates, what is the Bravais lattice?

    2)caculate the densities of the following solids:Al,Fe, Zn,and Si, whose atomic weights are respectively 26.98,55.85,65.37, and28.09.?

    3)the packing ratio is defined as the fraction of the total volume of the cell that is filled by atoms. Determine the the maximum value of this ratio for equal sphares located at the points of simple -cubic, body-centered-cubic, and face-centered-cubic crystals??

    4) Sketch the following planes and directions in a cubic unit cell:(122),[122],(112),[112]??
  2. jcsd
  3. Sep 24, 2006 #2
    2) Do you have an equation for this?? Your book should give you the equation and it's just a 'plug in the values' sort of question. Post what you think needs to be known to at least approach this question.

    3) Again post your thoughts on this. Can you tell me how many atoms are in a simple cubic, BCC or FCC structure? (This is just one of the variables you need to know).

    4) Host an image at http://imageshack.us/ of what you've attempted and let me know your difficulties. Maybe draw them by hand and scan an image onto your computer and host the image or draw an image on your computer and host it.

    Start by drawing your axes (x, y and z) and then draw the unit cell on these axis. I'm sure your book tells you the procedure to follow for determining the Miller indices of planes, which will allow you to draw your diagrams.

    When you post some additional thoughts I will gladly help you more. I don't mean to sound like an ass, but those are the rules. I understand that some questions you might be completely lost on, but you can at least point out what is stumping you exactly and even some basic concept behind the question.
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