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Unformatted text preview: 3.091 Fall Term 2009 Test #2 page 2 x y z x y z Problem #1 (22%) (a) For each unit cell above, draw the crystallographic feature indicated and label it clearly. (8%) (b) Named after Salvadore Dali, dalium (Da) is BCC. Its molar volume is 6.66 cm 3 /mol. Calculate the density of atoms in (001) of Da. Express your answer in atoms/cm 2 . (8%) (c) Here is the (011) plane in a unit cell of magnesium oxide (MgO) which is FCC. Indicate the positions of all atoms lying in the plane. Represent atoms as 2-dimensional slices of space-filling spheres. The values of ionic radii are Mg 2+ = 0.65 and O 2 = 1.34 . Your sketch need not be drawn to scale; however, you must convey relative values of the ionic dimensions. (6%) 3.091 Fall Term 2009 Test #2 page 3 Problem #2 (23%) (a) You discover that someone has been using your x-ray generator and has changed the target/anode. To determine the chemical identity of the new target, you go ahead and operate the x-ray generator and find the wavelength, , of the K peak to be 0.250 nm. What element is the target made of? peak to be 0....
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- Spring '09