What type of stoichiometric defecit is shoen by ZnS ?

Options

A. Schottky defect
B. Frenkel defect
C. Both Frenkel and Schottky defects
D. Non-stoichiometric defect

Answer

To determine the type of stoichiometric defect shown by ZnS (zinc sulfide), we need to analyze the characteristics of the compound and the types of defects that can occur in ionic solids.

### Step-by-Step Solution:

1. **Understanding Stoichiometric Defects**:
Stoichiometric defects are imperfections in the crystal lattice of a solid that affect the stoichiometry of the compound. The two main types of stoichiometric defects are Frenkel defects and Schottky defects.

2. **Identifying the Components of ZnS**:
ZnS is composed of zinc ions (Zn²⁺) and sulfide ions (S²⁻). Zinc is a transition metal, and the ionic sizes of Zn²⁺ and S²⁻ are significantly different.

3. **Analyzing Ionic Sizes**:
The ionic radius of Zn²⁺ is smaller than that of S²⁻. This large difference in size is a crucial factor in determining the type of defect.

4. **Determining the Type of Defect**:
- **Frenkel Defect**: This defect occurs when a cation (or anion) leaves its normal position in the lattice and occupies an interstitial site. This is common in compounds where the cation is smaller than the anion.
- **Schottky Defect**: This defect occurs when an equal number of cations and anions are missing from the lattice, maintaining charge neutrality.

5. **Conclusion**:
Given that Zn²⁺ is significantly smaller than S²⁻, it is more likely for the Zn²⁺ ions to occupy interstitial sites, leading to the formation of Frenkel defects in ZnS.

Therefore, the type of stoichiometric defect shown by ZnS is a **Frenkel defect**.

### Final Answer:
ZnS shows a **Frenkel defect**.

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