Ionic solids with Schottky defect may contain in their structure

Options

A. cation vacancies only
B. cation vacancies and interstitial cations
C. equal number of cation and anion vacancies
D. anion vacancies and interstitial anions

Answer

To solve the question regarding the structure of ionic solids with Schottky defects, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Schottky Defect**:
- A Schottky defect occurs in ionic solids when there are vacancies created in the crystal lattice due to the absence of both cations and anions. This means that an equal number of cations and anions are missing from their lattice sites.

2. **Identifying Vacancies**:
- In a Schottky defect, when a cation is missing from its lattice site, it creates a cation vacancy. Similarly, when an anion is missing, it creates an anion vacancy. Therefore, in a Schottky defect, we have vacancies for both cations and anions.

3. **Equal Number of Vacancies**:
- Since the definition of a Schottky defect specifies that there is an equal number of cation and anion vacancies, we can conclude that both types of vacancies are present in the structure.

4. **Evaluating the Options**:
- Now, let's evaluate the provided options:
- **Cation vacancies only**: Incorrect, as it does not account for anion vacancies.
- **Cation vacancies and interstitial cations**: Incorrect, as interstitial cations are not part of a Schottky defect.
- **Equal number of cation and anion vacancies**: Correct, as this is the definition of a Schottky defect.
- **Anion vacancies and interstitial anions**: Incorrect, as interstitial anions are not part of a Schottky defect.

5. **Conclusion**:
- The correct answer is that ionic solids with Schottky defects contain an equal number of cation and anion vacancies.

### Final Answer:
**Equal number of cation and anion vacancies.**

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