Zinc blende ZnS

Large deposits of free sulphur occur in America, Sicily and Japan. Combined sulphur occurs as sulphides, for example galena, PbS, zinc blende, ZnS, and iron pyrites, FeSj, and as sulphates, notably as gypsum or anhydrite, CaS04. 

The common ores of zinc are zinc blende, ZnS, and calamine, ZnC03. The metal is extracted (a) by roasting blende with air or by heating... 

Blende, /. blend, glance (specif., zinc blend, ZnS) blind, screen, shutter, shield, diaphragm, stop, baffle border. 

In theory, the III-V compound semiconductors and their alloys are made from a one to one proportion of elements of the III and V columns of the periodic table. Most of them crystallize in the sphalerite (zinc-blende ZnS) structure. This structure is very similar to that of diamond but in the III-V compounds, the two cfc sublattices are different the anion sublattice contains the group V atoms and the cation sublattice the group III atoms. An excess of one of the constituents in the melt or in the growing atmosphere can induce excess atoms of one type (group V for instance) to occupy sites of the opposite sublattice (cation sublattice). Such atoms are said to be in an antisite configuration. Other possibilities related with deviations from stoichiometry are the existence of vacancies (absence of atoms on atomic sites) on the sublattice of the less abundant constituent and/or of interstitial atoms of the most abundant one. 

Zinc occurs in nature, widely distributed. The principal ores are sphalerite (and wurtzite) known as zinc blende, ZnS gahnite, ZnAl204 calamine smith-sonite, ZnCOs franklinite, ZnFe204 and zincite, ZnO. Abundance in earth s crust is about 70 mg/kg and average concentration in sea water is about 10 pg/L. 

Zinc sulfate is produced as an intermediate in recovering zinc from mineral zinc blende, ZnS (see Zinc, Recovery). The mineral is roasted at about 1,000°C to form zinc oxide and sulfur dioxide which, on prolonged heating in excess air, converts to zinc sulfate ... 

The major ores of Zn are zinc blende ZnS (also known as sphalerite) and calamine ZnC03. Much more Zn is now produced from ZnS which is concentrated from its rock matrix by flotation or sedimentation. The concentrate is then roasted to generate ZnO, which is smelted with coke, or which is dissolved in H2SO4 and the solution is electrolyzed. 

Half tetrahedral every alternate site occupied Zinc blende ZnS, CuCl, y-AgI Wurtzite ZnS, PAgI... 

MX) types halite (NaCl), cesium chloride (CsCl), zinc blende (ZnS), and wurtzite (also ZnS) ... 

The difference was first demonstrated by Coster, Knol, and Prins (1930) in zinc blende (ZnS) crystals by using the Lanomalous phase displacement, which can be of the order of 10° and therefore produce very appreciable intensity changes, see James (1948), Dauben and Templeton (1955), and Pepinsky (1956).,... 

Sulfur is found in large quantities but in various forms throughout the world. It is found in metal ores such as copper pyrites or chalcopyrite (CuFeS2) and zinc blende (ZnS) and in volcanic regions of the world. Natural gas and oil contain sulfur and its compounds, but the majority of this sulfur is removed as it would cause environmental problems. Sulfur obtained from these sources is known as recovered sulfur and it is an important source of the element. It is also found as elemental sulfur in sulfur beds in Poland, Russia and the US (Louisiana). These sulfur beds are typically 200 m below the ground. Sulfur from these beds is extracted using the Frasch process, named after its inventor Hermann Frasch. 

Figure 6.1. The 3-2PT structure of zinc blende (ZnS). The P layers (S) are dark balls.

Figure 6.12. The 3 3PTT structure of fluorite (CaF2) with all T layers filled by F atoms (dark atoms) and Ca atoms in a ccp arrangement. The zinc blende (ZnS) structure with one T layer filled by S is shown for comparison.

Figure 6.13. The zinc blende (ZnS) structure is shown with the Mg atoms in the other T layer. They are combined to give a fluorite-like structure for MgAgAs.

Some intermetallic compounds have the same structures as those of simple polar compounds. Quite a few AM type intermetallic compounds have the NaCl (3 2PO, Section 5.1.1) structure, but usually for those differing significantly in electronegativities. Table 5.1 includes many compounds of the types MP, MAs, MSb, and MBi. The NiAs structure (2-2PO, Section 5.2.1) is found for a few MAs and MSb compounds (Table 5.5), the MSn compounds of Fe, Ni, Cu, Pd, Pt, Rh, and Au, and MnBi, NiBi, PtBi, and RhBi. The ZnS structures (CN 4) are not usually encountered for intermetallic compounds. The compounds of Al, Ga, and In with P, As, and Sb have the zinc blende (ZnS, 3 2PT, Section 6.1.1) structure. These are semiconductors or insulators. Because the bcc structure is common for metals, it is not surprising that many 1 1 intermetallic compounds have the CsCl structure (3 2PTOT, Section 7.2.1). A few of these intermetallic compounds are included in Table 7.1 a more extensive list is given in Table 9.1. 

Zinc blende, ZnS, reacts when strongly when heated in air (2ZnS + 302 - 2ZnO + 2S02). (a) How many pounds... 

Many less electropositive metals known as chalcophiles are found commonly as sulphide minerals some important examples are pyrites (FeS2), sphalerite (zinc blende, ZnS), molybdenite (MoS2), cinnabar (HgS) and galena (PbS). Volatile sulphur compounds such as H2S and organic compounds are also found... 

---