Question

7. A crystalline solid consists of atoms stacked up in a repeat- ing lattice structure. Consider a crystal as shown in Fig. ure P1.7a. The atoms reside at the corners of cubes of side L = 0.200 nm. One piece of evidence for the regular arrangement of atoms comes from the flat surfaces along which a crystal separates, or cleaves, when it is broken. Sup- pose this crystal cleaves along a face diagonal as shown in Figure P1.7b. Calculate the spacing d between two adjacent atomic planes that separate when the crystal cleaves.

Answer 1

Consider Dis the distance of the face diagonal crystal cube can be calculated by using pythagoream theorem D={+ =VL Consider d is the spacing between the two adjacent diagonals of atomic planes As shown from the figure, spacing between diagonal planes is half of the distance between diagonally adjacent atoms on a flat plane, that is, Vac = 0.2mm v2 = 10.141nm (or) 1.41A