The Point Defect in Homogeneous Solids

We begin by identifying the various defects which can arise in solids and later will show how they can be manipulated to obtain desirable properties not found in naturally formed solids. Let us look first at the homogeneous t5T e of solid. We will first restrict our discussion to solids which are stoichiometric, and later will examine solids which can be classified as non-stolchlometric , or having an excess of one or another of one of the 

Suppose you were given the problem of identifying defects in a homogeneous solid. Since all of the atoms in this t e of solid are the same, the problem is somewhat simplified over that of the heterogeneous solid (that is- a solid containing more than one type of atom or ion). After some introspection, you could speculate that the homogeneous solid could have the following types of point defects  

- Types of Point Defects Expected in a Homogeneous Solid 

On the left are the two types of point defects which involve the lattice itself, while the others involve Impurity atoms (Note that interstitial atoms can involve either an impurity atom or the same atom that makes up the lattice structure itself). Indeed, there do not seem to anymore than these four, and indubitably, no others have been observed. Note that we are limiting our defect family to point defects in the lattice and are Ignoring line and volume defects of the lattice. These four point defects, given above, are illustrated in the following diagram, given as 2.1.3. on the next page. 

Defects Which Can Occur in a Homogeneous Hexagonal Lattice 

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