The defect shown by ZnS is

Options

A. Frenkel defect
B. Schottky defect
C. Non-stoichiometric defect
D. Both (a) and (b)

Explanation

### Step-by-Step Solution:

1. **Identify the Type of Crystal**:
- Zinc sulfide (ZnS) is an ionic crystal composed of zinc cations (Zn²⁺) and sulfide anions (S²⁻).

2. **Understand the Size Difference**:
- The size of the zinc cation (Zn²⁺) is smaller compared to the size of the sulfide anion (S²⁻). This size difference is significant and plays a crucial role in determining the type of defect present in the crystal.

3. **Define the Frankel Defect**:
- A Frankel defect occurs in ionic crystals when a cation leaves its normal lattice site and occupies an interstitial site, creating a vacancy at its original position. This defect typically arises when there is a considerable size difference between the cation and anion.

4. **Illustrate the Defect Formation**:
- In the case of ZnS, the smaller Zn²⁺ ions can move into the interstitial spaces of the crystal lattice. This displacement creates a vacancy where the Zn²⁺ ion was originally located, while the overall density of the crystal remains unchanged.

5. **Conclude the Type of Defect**:
- Since the smaller cations (Zn²⁺) are displaced into interstitial sites and vacancies are created, the defect shown by ZnS is identified as a **Frankel defect**.

### Final Answer:
The defect shown by ZnS is a **Frankel defect**.

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