Identify the defect developed when an ion of an ionic compound is missing from its regular site and occupies an interstitial position between lattice points.
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The key difference between Schottky and Frenkel defects is that Schottky involves the absence of both an anion and cation, whereas Frenkel involves only one ion displaced to an interstitial site.
Step 1: Understanding the Question:
We need to identify the specific type of point defect where an ion migrates from its lattice site to an interstitial space. Step 2: Detailed Explanation:
Let's look at the characteristics of the given defects:
(A) Schottky defect: Equal numbers of cations and anions are completely missing from the crystal lattice. This decreases the density.
(B) Frenkel defect: An ion (usually the smaller cation) is displaced from its regular lattice site and occupies a nearby interstitial position. The overall density remains unchanged.
(C) Substitutional impurity defect: A foreign atom replaces a host atom at its lattice site.
(D) Interstitial impurity defect: A foreign atom occupies the void spaces (interstitial sites) between lattice points. Step 3: Final Answer:
The described defect is the Frenkel defect.