Arrangement of Sulphur in Zinc Blende and Wurtzite Structures

The arrangement of atoms in crystals can have a significant impact on their properties. In the case of zinc blende and wurtzite structures, the arrangement of sulphur atoms differs, resulting in distinct crystal structures.

Zinc Blende Structure:

The zinc blende structure is a common crystal structure found in various compounds, including zinc sulfide (ZnS). It is a type of cubic close packing (CCP) structure. Here is how the arrangement of sulphur atoms occurs in the zinc blende structure:

1. Cubic Close Packing:
- In a cubic close packing structure, the atoms are arranged in layers of spheres, with each layer being offset from the previous one.
- The layers are formed by placing spheres in the depressions (octahedral voids) between the spheres in the layer below.
- The resulting structure has a cubic symmetry, with coordination number of 6.

2. Sulphur Arrangement:
- In the zinc blende structure, sulphur atoms occupy the tetrahedral voids between the zinc atoms.
- The arrangement of sulphur atoms can be visualized as a face-centered cubic (fcc) arrangement of zinc atoms, with one sulphur atom located at the center of each tetrahedral void.

Wurtzite Structure:

The wurtzite structure is another common crystal structure found in various compounds, including zinc sulfide (ZnS). It is a type of hexagonal close packing (HCP) structure. Here is how the arrangement of sulphur atoms occurs in the wurtzite structure:

1. Hexagonal Close Packing:
- In a hexagonal close packing structure, the atoms are arranged in layers of spheres, with each layer being offset and aligned with the previous one in a hexagonal pattern.
- The layers are formed by placing spheres in the depressions (hexagonal voids) between the spheres in the layer below.
- The resulting structure has a hexagonal symmetry, with coordination number of 6.

2. Sulphur Arrangement:
- In the wurtzite structure, sulphur atoms occupy half of the tetrahedral voids between the zinc atoms in one layer, while the other half remains vacant.
- The arrangement of sulphur atoms can be visualized as an alternating sequence of layers containing only zinc atoms and layers containing zinc and sulphur atoms.

Conclusion:

To summarize, the arrangement of sulphur atoms in the zinc blende structure is based on a cubic close packing (CCP) arrangement, with sulphur atoms occupying the tetrahedral voids between the zinc atoms. On the other hand, the arrangement of sulphur atoms in the wurtzite structure is based on a hexagonal close packing (HCP) arrangement, with sulphur atoms occupying half of the tetrahedral voids between zinc atoms in one layer. Therefore, the correct answer is option 'D' - Simple cubic packing in both the structures.