Question

What is the effect of pressure on the structures of the ionic crystals of the type AB?

Answer 1

When pressure is applied to ionic crystals of type AB:

1. Coordination Number Increases: High pressure forces ions closer together, often changing the coordination number from 6 : 6 (e.g., NaCl structure) to 8 : 8 (e.g., CsCl structure) for tighter packing.

2. Phase Transition: It can cause phase transitions to denser structures, like NaCl transforming into a CsCl-type structure at high pressures.

3. Volume Reduction: The unit cell volume decreases, increasing lattice energy and overall stability.