Antifluorite structure is derived from fluorite structure by:

Options

A. heating fluorite structure crystal lattice
B. subjecting fluorite structure to high pressure
C. Inter chaning the positions of positive and negative ions in the lattice
D. none of these

Answer

To derive the antifluorite structure from the fluorite structure, we need to understand the arrangement of ions in both structures. Here’s a step-by-step breakdown of the process:

### Step 1: Understand the Fluorite Structure
- The fluorite structure has the general formula MX2, where M is a cation and X is an anion.
- A common example is calcium fluoride (CaF2). In this structure:
- The calcium ions (Ca²⁺) are arranged in a face-centered cubic (FCC) lattice.
- The fluoride ions (F⁻) occupy all the tetrahedral voids in the lattice.

### Step 2: Understand the Antifluorite Structure
- The antifluorite structure has the general formula M2X, where M is a cation and X is an anion.
- A common example is sodium oxide (Na2O). In this structure:
- The oxide ions (O²⁻) are arranged in a face-centered cubic (FCC) lattice.
- The sodium ions (Na⁺) occupy all the tetrahedral voids in the lattice.

### Step 3: Identify the Key Difference
- The key difference between the fluorite and antifluorite structures is the position of the cations and anions:
- In the fluorite structure, the cations occupy the FCC lattice, and the anions occupy the tetrahedral voids.
- In the antifluorite structure, the anions occupy the FCC lattice, and the cations occupy the tetrahedral voids.

### Step 4: Deriving Antifluorite from Fluorite
- To derive the antifluorite structure from the fluorite structure, we need to **interchange the positions of the cations and anions**.
- This means that the cations (previously in the FCC lattice) will move to the tetrahedral voids, and the anions (previously in the tetrahedral voids) will take the FCC lattice positions.

### Conclusion
- Thus, the antifluorite structure is derived from the fluorite structure by interchanging the positions of positive and negative ions in the lattice.

### Final Answer
The correct option is: **Interchanging the position of positive and negative ions in the lattice.**

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