At zero kelvin most of the ionic crystals possess

Options

A. Frenkel defect
B. Schottky defect
C. Metal excess defect
D. No defect

Answer

To solve the question "At zero kelvin most of the ionic crystals possess", we need to understand the behavior of ionic crystals at absolute zero temperature (0 Kelvin).

### Step-by-Step Solution:

1. **Understanding Absolute Zero**:
- Absolute zero (0 Kelvin) is the theoretical temperature at which a system reaches its minimum energy state. At this temperature, all atomic and molecular motion ceases.

2. **Behavior of Ionic Crystals**:
- Ionic crystals are composed of positively and negatively charged ions held together by strong electrostatic forces. At absolute zero, there is no thermal energy to cause any vibrations or movements in these ions.

3. **Defects in Ionic Crystals**:
- Defects in ionic crystals, such as Frenkel defects and Schottky defects, occur due to the movement of ions or vacancies created by thermal energy.
- **Frenkel Defect**: This defect occurs when an ion is displaced from its normal position to an interstitial site, creating a vacancy.
- **Schottky Defect**: This defect involves the creation of vacancies for both cations and anions, maintaining charge neutrality.

4. **Effect of Temperature on Defects**:
- As the temperature increases, the thermal energy allows ions to move, leading to the formation of defects like Frenkel and Schottky defects.
- However, at 0 Kelvin, since there is no thermal energy, there will be no movement of ions, and thus no defects can form.

5. **Conclusion**:
- Therefore, at 0 Kelvin, ionic crystals will possess **no defects** because the ions are completely stationary and unable to create any vacancies or interstitials.

### Final Answer:
At zero kelvin, most of the ionic crystals possess **no defect**.

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