Difference Between Zinc Blende and Wurtzite

The key difference between zinc blende and wurtzite is that zinc blend is cubic, whereas wurtzite has a hexagonal structure.

Zinc blende and wurtzite are the two major crystal structures of the chemical compound zinc sulfide ( ZnS). These two structures are polymorphs of zinc sulfide. Thermodynamically, zinc blend is more stable than wurtzite structure.

1. Overview and Key Difference
2. What is Zinc Blende
3. What is Wurtzite
4. Side by Side Comparison – Zinc Blende vs Wurtzite in Tabular Form
5. Summary

What is Zinc Blende?

Zinc blende is the cubic crystals structure shown by zinc sulfide (ZnS). The structure has a diamond-like network. It is a thermodynamically more favoured structure than the other form of zinc sulfide. However, it can change its structure upon changing the temperature. For instance, zinc blende can become wurtzite if we change the temperature.

We can characterize the zinc blende as a cubic close-packed (CCP) and a face-centred cubic structure. Also, this structure is denser than the wurtzite structure. However, when the temperature increases, the density tends to decrease; therefore, a conversion can take place from zinc blende to wurtzite. Besides, in this structure, the cations (zinc ions) occupy one of the two types of tetrahedral holes present in the structure, and it has four asymmetric units in its unit cell.

What is Wurtzite?

Wurtzite is the hexagonal crystal structure shown by zinc sulfide (ZnS). We call this crystal structure hexagonal close packing structure (HCP). We can characterize it by 12 ions in the corners of each unit cell, which creates a hexagonal prism structure.

However, this structure has low thermodynamic stability; thus, it slowly converts into a zinc blende structure. Also, this structure has the cations (zinc ions) occupying one of the two types of tetrahedral holes present in the structure, but it has two asymmetric units in its unit cell.

What is the Difference Between Zinc Blende and Wurtzite?

Zinc blende and wurtzite are two forms of zinc sulfide. However, the key difference between zinc blende and wurtzite is that zinc blend is cubic, whereas wurtzite has a hexagonal structure. Further, the density of zinc blende is higher than wurtzite.

Moreover, one more significant difference between zinc blende and wurtzite is that the zinc blend has four asymmetric units in its unit cell, while the wurtzite has two asymmetric units. Besides, when considering the thermodynamic stability of these structures, zinc blend is thermodynamically more favoured; thus, the wurtzite structure tends to convert into zinc blend slowly.

Summary – Zinc Blende vs Wurtzite

Zinc blend and wurtzite are the two major polymorphic structures of zinc sulfide. Since zinc blend is more thermodynamically stable than wurtzite, the wurtzite form tends to convert into zinc blend slowly. The key difference between zinc blende and wurtzite is that zinc blend is cubic, whereas wurtzite has a hexagonal structure.

Reference:

1.“6.11E: Structure – Zinc Blende (ZnS).” Chemistry LibreTexts, Libretexts, 5 June 2019, Available here.

Image Courtesy:

1. “Sphalerite-unit-cell-depth-fade-3D-balls” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia
2. “Wurtzite cellGIF” By Catvector – Own work (CC BY-SA 4.0) via Commons Wikimedia