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Crystal Structure 1 3.1 Some Basic Concepts of Crystal Structure ...

Crystal Structure 1 3.1 Some Basic Concepts of Crystal Structure ...

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<strong>Crystal</strong> <strong>Structure</strong><br />

Bragg Diffraction and Reciprocal Lattice Vectors<br />

Fig. <strong>3.1</strong>5<br />

Reciprocal Vectors<br />

The reciprocal lattice <strong>of</strong> a Bravais lattice constructed by the set <strong>of</strong> primitive vectors, a, b<br />

and c is one that has primitive vectors given by:<br />

<br />

<br />

<br />

b c <br />

<br />

c a <br />

<br />

a b<br />

A 2 B 2 C <br />

a b c<br />

a b c<br />

2 <br />

a b c<br />

(3.6)<br />

Examples:<br />

(1) Reciprocal lattice to simple cubic lattice<br />

For sc lattice, we may choose the following set <strong>of</strong> primitive vectors:<br />

<br />

a aˆ,<br />

a aˆ,<br />

a aˆ,<br />

1<br />

x<br />

2<br />

y<br />

3<br />

z<br />

We may then determine the reciprocal lattice vectors b 1 , b 2 and b 3 using eqn. 3.6:<br />

<br />

<br />

a2<br />

a3<br />

2<br />

b 2 xˆ<br />

1<br />

.<br />

3<br />

a a<br />

Similarly,<br />

2<br />

2<br />

b yˆ<br />

2<br />

and b3<br />

zˆ<br />

a<br />

a<br />

9

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