Posted by Steve Simon on March 12, 2014, 9:49 pm, in reply to "Re: A.3.1"
Oh right. Sorry!
You should be extremely close to the exact answer (within a few percent). And you should be seeing all the right peaks in order. However, if I remember correctly, the lattice constant is off by a few percent compared to the "accepted" value, and there is not an obvious answer to why!! But this is real data so there must be a good reason. My best guess is that the error comes from thermal expansion. The stated density may have been measured at room temperature and the X ray measurements might have been done at low temperature. In fact, if you make this assumption and put in the known thermal expansion of Aluminum, you do discover that the lattice constant should change by a few percent between low and room temperature.
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