ZnS has a unique structure type compared to other molecules, having different types of individual structures. ZnS can have a zinc blende struck, ais a "diamond-type net, "or rk", and at a different temperature, ZnS can become the wurtzite structure with a hexagonal type symmetry. The zinc blende structure is more thermodynamically favoured; however, because of the wurtzite structures' slow construction, both forms of ZnS can be found. Zinc blend is a compound in two forms: sphalerite and wurtzite. These are characterized by a 1:1 stoichiometric ratio of Zinc to Sulfur. It maintains a tetrahedral arrangement in both states. Zinc sulfide (ZnS) is a unique compound that forms two crystalline structures. These two polymorphs are wurtzite and zincblende (also known as sphalerite). Wurtzite has a hexagonal design, while zincblende is cubic. It is characterized by single bonds between each atom and the maintenance of a 1:1 zinc-to-sulfur ratio. Density tends to decrease as temperature increases. In this case, since ccp structures are dense than hcp structures, a conversion from sphalerite to wurtzite occurs naturally over time at a rate similar to that of diamond to graphite. The sphalerite structure is favoured at 298k by 13kJ/mol, but at 1296K, the transition to wurtzite occurs. Since the number of atoms in a single unit cell of Zn and S is the same, it is consistent with the formula ZnS. The ionic radius for Zn2+ is 74pm, and for S2- is 190pm. Therefore the ratio between cationic and anionic radii in the zinc blend is 0.39 (74pm/190 pm). This suggests a tetrahedral ion arrangement and four nearest neighbours from standard crystal structure prediction tables. Therefore, four sulfur atoms surround each zinc atom, and four zinc atoms surround each sulfur atom.2 The coordination number, the number of electron pairs donated to a metal by its ligands, for both zinc and sulfur is four.1,2 The difference between wurtzite and zincblende lies in the different arrangements of layers of ions. If you are looking for high quality, high purity and cost-effective zinc sulfide, or if you require the latest price of zinc sulfide, please feel free to email contact mis-asia.