The defect when an ion occupies an interstitial position in the crystal lattice is called

Options

A. Crystal defect
B. Frenkel defect
C. Schottky defect
D. None of the above

Answer

To solve the question regarding the defect when an ion occupies an interstitial position in the crystal lattice, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Crystal Lattice**:
- A crystal lattice is a three-dimensional arrangement of atoms or ions in a crystalline material. The positions in this lattice can be occupied by ions of different sizes.

2. **Identifying Ion Sizes**:
- In a crystal lattice, there are typically cations (positively charged ions) and anions (negatively charged ions). The sizes of these ions can vary significantly, with cations usually being smaller than anions.

3. **Interstitial Positions**:
- Interstitial positions are the spaces between the regular lattice points in the crystal structure. Smaller ions can fit into these spaces without disrupting the overall structure of the lattice.

4. **Defects in Crystal Lattice**:
- When an ion occupies an interstitial position, it creates a defect in the crystal lattice. This type of defect is specifically associated with the presence of smaller ions that can fit into the gaps.

5. **Types of Defects**:
- There are two main types of defects in crystal lattices:
- **Schottky Defect**: This occurs when an equal number of cations and anions are missing from the lattice, maintaining charge neutrality.
- **Frankel Defect**: This occurs when a smaller ion (usually a cation) occupies an interstitial site, leaving a vacancy behind.

6. **Conclusion**:
- The defect that occurs when an ion occupies an interstitial position in the crystal lattice is known as the **Frankel defect**.

### Final Answer:
The defect when an ion occupies an interstitial position in the crystal lattice is called the **Frankel defect**.

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