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Sphalerite and wurtzite are the two polymorphs of Zinc Sulphide (ZnS). Sphalerite follows the space group F-43m, wurtzite is of the space group P63mc, and both polymorphs have the same formula of (Zn, Fe)S. The crystal chemical relationship between the two can be discussed by looking at the capability of transformation between the two polymorphs, known as polymorphism. This is due to the same SnS4 polyhedral found in both. Yet even though this is so, the two differ when we look at the forms of their crystal structures. Sphalerite has a lattice structure that is cubic 2L (1 1) while wurtzite has a hexagonal 3L (3) ~ lattice system. In the figure below (Figure 1), we have constructed a sphalerite model, created with the ATOMS program. The diagram has been labelled with yellow, green, and …show more content…
Each of these coloured marking represents a layer of the tetrahedral structure, which are differentiated from one another. The yellow layer is followed by the green layer and blue layer. Notice that for the tetrahedrons for the sphalerite model all have the same orientation, and they face the same direction, rather like a pyramid being stacked up. This orientation creates a layered stacking, which follows an “ABC” sequence. In the same fashion as the above, a model for wurtzite, the less common polymorph, has also been constructed (Figure 2). This model shows how the tetrahedrons following the hexagonal form are rotated between layers, and these are represented by the different shades of colour. Instead of the above sequence, the hexagonal form has an “AB” structure between layers. The “ABC” and “AB” sequences can be linked to twist sequences which we will be looking at in a later paragraph. Arguably, both sphalerite and wurtzite are rather similar in terms of symmetry, which allows them to transform into one form or the other when placed under different
Sphalerite and wurtzite are the two polymorphs of Zinc Sulphide (ZnS). Sphalerite follows the space group F-43m, wurtzite is of the space group P63mc, and both polymorphs have the same formula of (Zn, Fe)S. The crystal chemical relationship between the two can be discussed by looking at the capability of transformation between the two polymorphs, known as polymorphism. This is due to the same SnS4 polyhedral found in both. Yet even though this is so, the two differ when we look at the forms of their crystal structures. Sphalerite has a lattice structure that is cubic 2L (1 1) while wurtzite has a hexagonal 3L (3) ~ lattice system. In the figure below (Figure 1), we have constructed a sphalerite model, created with the ATOMS program. The diagram has been labelled with yellow, green, and …show more content…
Each of these coloured marking represents a layer of the tetrahedral structure, which are differentiated from one another. The yellow layer is followed by the green layer and blue layer. Notice that for the tetrahedrons for the sphalerite model all have the same orientation, and they face the same direction, rather like a pyramid being stacked up. This orientation creates a layered stacking, which follows an “ABC” sequence. In the same fashion as the above, a model for wurtzite, the less common polymorph, has also been constructed (Figure 2). This model shows how the tetrahedrons following the hexagonal form are rotated between layers, and these are represented by the different shades of colour. Instead of the above sequence, the hexagonal form has an “AB” structure between layers. The “ABC” and “AB” sequences can be linked to twist sequences which we will be looking at in a later paragraph. Arguably, both sphalerite and wurtzite are rather similar in terms of symmetry, which allows them to transform into one form or the other when placed under different