When NaCl crystal is doped with `MgCl_(2)`,the nature of defect produced is

Options

A. Interstitial defect
B. Schottky defect
C. Frenkel defect
D. None of these

Explanation

To determine the nature of the defect produced when NaCl crystal is doped with MgCl₂, we can follow these steps:

### Step 1: Understand the Composition of NaCl
NaCl (sodium chloride) consists of Na⁺ ions and Cl⁻ ions arranged in a cubic lattice structure. Each Na⁺ ion is surrounded by Cl⁻ ions and vice versa.

### Step 2: Identify the Doping Element
When MgCl₂ is added to NaCl, magnesium ions (Mg²⁺) are introduced into the crystal lattice. Magnesium has a +2 charge.

### Step 3: Charge Balance Consideration
To maintain electrical neutrality in the crystal lattice, the introduction of a Mg²⁺ ion (which has a +2 charge) necessitates the removal of two Na⁺ ions (which each have a +1 charge). Thus, for every Mg²⁺ ion that occupies a lattice site, two Na⁺ ions are removed from the lattice.

### Step 4: Formation of Vacancies
The removal of two Na⁺ ions creates vacancies (or holes) in the lattice. These vacancies are essential for maintaining the charge balance in the crystal after the introduction of the Mg²⁺ ion.

### Step 5: Identify the Type of Defect
The defect created by the removal of Na⁺ ions and the introduction of Mg²⁺ ions is known as a **Schottky defect**. In a Schottky defect, both cation and anion vacancies are created to maintain charge neutrality. In this case, since two Na⁺ ions are removed for every Mg²⁺ ion added, it results in a decrease in density due to the presence of vacancies.

### Conclusion
Therefore, the nature of the defect produced when NaCl is doped with MgCl₂ is a **Schottky defect**.

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