Cations are present in the interstitial sites in

Options

A. Frenkel defect
B. Schottky defect
C. Vacancy defect
D. Metal deficiency defect

Explanation

To solve the question "Cations are present in the interstitial sites in", we need to analyze the different types of defects in solids. Here’s a step-by-step solution:

### Step 1: Understand the Types of Defects
There are several types of defects in crystalline solids, including:
- Frenkel defect
- Schottky defect
- Vacancy defect
- Metal deficiency defect

### Step 2: Define Frenkel Defect
A **Frenkel defect** occurs when a cation leaves its normal lattice position and occupies an interstitial site. This results in a vacancy where the cation was originally located and an interstitial site being occupied by the cation.

### Step 3: Define Schottky Defect
A **Schottky defect** involves the absence of both cations and anions from their lattice sites, maintaining electrical neutrality. In this case, there are no interstitial cations present, as both types of ions are missing from their normal positions.

### Step 4: Define Vacancy Defect
A **vacancy defect** refers to the absence of ions at lattice points, leading to vacant sites in the crystal structure. This defect does not involve cations occupying interstitial sites.

### Step 5: Define Metal Deficiency Defect
A **metal deficiency defect** occurs when there are fewer cations than anions in the structure, leading to an imbalance. This defect does not involve cations occupying interstitial sites.

### Step 6: Conclusion
Based on the definitions and characteristics of the defects:
- Cations are specifically present in interstitial sites in the **Frenkel defect**.

Thus, the correct answer to the question is **Frenkel defect**.

### Final Answer
Cations are present in the interstitial sites in **Frenkel defect**.

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