Crystal structure(Do questions 1 to 8 in assignment note book rest in class note book)

1. Calculate the lattice constant of potassium bromide. Density of Potassium bromide is 2700kgm2

and

belongs to fcc lattice. Molecular weight of Potassium bromide is 119.0.

2. For a simple cubic lattice of the lattice parameter 2.04 Å , calculate the spacing of (212) lattice planes.

3. Calculate the interplanar spacing between (112) planes in a simple cubic crystal lattice whose lattice constant is 4.2×10−8 cm.

4. A certain orthorhombic crystal has axial units or a: b: c or 0.424:1:0.367. Find the miller indices of crystal faces whose intercepts are :

i) 0.212 : 1 : 0.183ii) 0.424 : α : 0.123

5. Copper has fcc structure and atomic radius is 1.278Å. Calculate its density. Atomic mass of copper is 63.54 amu.

6. Lead is a face centered cubic with an atomic radius of 1.746Å. Find the spacing of (i) 200 planes and (ii) 220 planes.

7. GaAs has its principle planes separated at 5.6534Å. The first order of Bragg reflection is located at

13040' . Calculate (a) the wavelength of the x-rays and (b) the angle for the second order Bragg reflection.

8. Draw the following planes, the miller indices are : (201), (222 ) , (211 ) .

9. Monochromatic x-rays of wavelength 0.34 Å are incident on a crystal with 1.5Å as inter atomic spacing at a glancing angle of 270. Find the order of the reflection.

10. The glancing angle for the first order spectrum was observed to be 80 in a Bragg’s x-ray spectrometer. Calculate the spacing between the planes if the wavelength of x-rays used is 0.78 Å.

11. Bragg’s angle corresponding to the first order reflection from (111) planes in a crystal is 300, when x-rays of wavelength 1.75 Å are used. Calculate the inter atomic spacing.