Frenkel defect is shown by crystals having __________ coordination number and ___________difference in the size of the cations and the anions.

Answer

To answer the question regarding the Frenkel defect, we can break it down into the following steps:

### Step 1: Understanding Frenkel Defect
The Frenkel defect is a type of point defect in a crystal lattice where an ion (usually a cation) is displaced from its normal position to an interstitial site, creating a vacancy at its original position.

### Step 2: Coordination Number
The coordination number refers to the number of nearest neighbors surrounding a particular atom or ion in a crystal structure. In the case of Frenkel defects, it is typically observed in crystals with a **low coordination number**. This is because a low coordination number allows for more flexibility in the arrangement of ions, making it easier for an ion to occupy an interstitial site.

### Step 3: Size Difference of Ions
Frenkel defects are also characterized by a **large difference in the size of cations and anions**. This size disparity is crucial because it allows the smaller cation to fit into the interstitial spaces of the lattice without significantly disturbing the overall structure of the crystal.

### Step 4: Conclusion
Thus, we can conclude that the Frenkel defect is shown by crystals having a **low coordination number** and a **large difference in the size of the cations and anions**.

### Final Answer
Frenkel defect is shown by crystals having **low coordination number** and **large difference in the size of the cations and the anions**.

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