1.

The lengthof a unit cell in the NI Crystal is 0.352 nm. The diffraction of X-rays of 0.154 nm wavelength (lambda) from a Ni crystal occurs at 22.2^(@), 55.9^(@) and 38.2^(@) . By using Bragg's law, (nlambda=2d "sin"theta) , and assuming that the diffractions are first order (n=1), the distance are calculated to be 0.204 nm , 0.176 nm and 0.124 nm The various structures for the Ni crystal are represented as: This distance (d) of 0.124 nm represent which structure?

Answer»

I
II
III
All

Solution :The DISTANCE 0.124 nm CORRESPONDS of times the unit cell dimension, i.e., one -fourth of the distance from one edge of the cell to the opposite edge (figII. The plane intersects the face-centered atoms of the two SIDES. The plane including the edge atoms is equivalent OT the plane across the center of the unit cell.


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