Question

Q1- The atoms in a crystal are modelled as hard spheres in contact. Calculate the Atomic radius in a fcc lattice with lattice constant 3.6 A

Q2-

(a) The atomic in a crystal are modelled as hard spheres in constant. Calculate the atomic radius in a fcc lattice with lattice constant 3.6 A.

(b) Consider three-dimensional simple cubic lattice with lattice constant a. What is the distance from the center to a corner of the first Brillouin Zone in the reciprocal lattice ?

(c) In an X-ray diffraction experiment with radiation of wavelength 1.54 A, a first order Diffracted beam was found at a Bragg angle q=19.6 , Calculate the distant between the Atomic planes giving rise this diffraction peak.

(d) Calculate the second diffraction angle ( counting from low angles ) obtained from diffraction of X-rays of wavelength 1.54 A. from AgCl (FCC) and state its Miller indices .

Q3- Consider a two-atomic one-dimensional chain considering of K+ and Br- ions. The force constant between 21 N/m. Calculate the highest vibration frequency and the wavelength of light that is absorbed by take into account interactions between nearest neighbors only.

Answer 1

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