Dopping of AgCl crystals with `CdCl_(2)` results in:

Options

A. Schottky defect
B. Frenkel defect
C. Substitutional cation vacancy
D. Formation of F-centres

Answer

To solve the question regarding the doping of AgCl crystals with CdCl₂, we will follow these steps:

### Step-by-Step Solution:

1. **Understanding Doping**:
- Doping refers to the process of adding impurities to a pure crystal. In this case, cadmium chloride (CdCl₂) is being added to pure silver chloride (AgCl) crystals.

2. **Identifying the Ions**:
- In AgCl, silver (Ag) exists as a unipositive ion (Ag⁺), while chloride (Cl) is a negative ion (Cl⁻).
- Cadmium chloride (CdCl₂) contains cadmium (Cd) as a dipositive ion (Cd²⁺) and two chloride ions (Cl⁻).

3. **Replacement of Ions**:
- When CdCl₂ is introduced into the AgCl lattice, the dipositive cadmium ion (Cd²⁺) can replace two unipositive silver ions (Ag⁺).
- This means that for every Cd²⁺ ion introduced, two Ag⁺ ions are removed from the lattice.

4. **Formation of Vacancies**:
- The replacement of two Ag⁺ ions by one Cd²⁺ ion creates a vacancy in the lattice because there are now fewer cations present than before.
- This vacancy is specifically a cationic vacancy since a cation (Ag⁺) is being replaced by another cation (Cd²⁺).

5. **Conclusion**:
- The result of doping AgCl crystals with CdCl₂ is the formation of a substitutional cationic vacancy. This is because two unipositive silver ions are replaced by one dipositive cadmium ion, leading to a missing cation in the lattice.

### Final Answer:
Doping of AgCl crystals with CdCl₂ results in **substitutional cationic vacancy**.

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