Beryllium chalcogenides

The chalcogenides of Be, Zn, Cd, and Hg are often referred to as II-VI semiconductors. They all have a zinc blende-type structure. The band gap decreases with increasing size of the metal from 3.0 eV in beryllium to 0.02 eV in mercury. The II-VI semiconductors find applications in solar cells, IR detectors, and optical conununication devices. 

Beryllium, because of its small size, almost invariably has a coordination number of 4. This is important in analytical chemistry since it ensures that edta, which coordinates strongly to Mg, Ca (and Al), does not chelate Be appreciably. BeO has the wurtzite (ZnS, p. 1209) structure whilst the other Be chalcogenides adopt the zinc blende modification. Bep2 has the cristobalite (SiOz, p. 342) structure and has only a very low electrical conductivity when fused. Bc2C and Bc2B have extended lattices of the antifluorite type with 4-coordinate Be and 8-coordinate C or B. Be2Si04 has the phenacite structure (p. 347) in which both Be and Si... 

The physicochemical properties of beryllium compounds and alloys have been reviewed subjects include phase diagrams, crystal structure, and density data on alloys and compounds, with a special section devoted entirely to halides and chalcogenides. ... 

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