Oxide wurtzite structure

Many divalent metal oxides and sulfides such as BeO, ZnO, BeS, MnS, ZnS. CdS, and HgS adopt the zinc blende or wurtzite structures, or occasionally both. Other compounds with these structures include Agl, NH F, and SiC. 

V. Oxides and Halides with the Wurtzite Structure Surface Structures, Reactivity, and Catalytic Activity... 

Zinc oxide (ZnO) is an oxidic compound naturally occurring as the rare mineral zincite, which crystallizes in the hexagonal wurtzite structure P63inc [16]. The mineral zincite was discovered in 1810 by Bruce in Franklin (New Jersey,... 

The spinel structure and spinel related structures are found in a large number of oxides. The (111) face is usually the lowest surface energy face, so it is typically easy to prepare. The oxygen lattice is face-centred cubic, which presents a similar stacking layer along [1 1 1] as found in the wurtzite structure along [0 0 0 1],... 

In addition to the oxides, the other six chalcogenides are also known. Table 15-3 shows the structures of the eight compounds. Clearly, with the sole exception of CdO, the chalcogenides of zinc and cadmium prefer tetrahedral coordination, though preference for the cubic zinc blende structure or the hexagonal wurtzite structure varies irregularly. 

Beryllium oxide is covalent and has a zinc blende (wurtzite) structure, but all the others are ionic and have a rock salt structure (Figure 3). Attempts to predict the structures (using the ionic sizes and the radius ratio) only are partly successfijl. 

O Keeffe, M, C. L. Shavers, and B. G. Hyde (1981). Cation packing and molar volume in oxides and nitrides with the wurtzite structure. J. Solid State Chem. 39, 265-67. 

Zinc oxide (ZnO, wurtzite structure) eliminates oxygen on heating to form nonstoichio-metric colored phases, Zni+xO with x < 70 ppm. ZnO is almost transparent and is used as white pigment, polymer stabilizer, emollient in zinc ointments, creams and lotions, as well as in the production of Zu2Si04 for TV screens. A major application is in the rubber industry to lower the temperatures and to raise the rate of vulcanization. Furthermore, it is an n-type semiconductor (band gap 3.37 eV) and shows piezoelectric properties, making zinc oxide useful for microsensor devices and micromachined actuators. Other applications include gas sensors , solar cell windows and surface acoustic devices. ZnO has also been considered for spintronic application because of theoretical predictions of room-temperature ferromagnetism . 

Cadmium(II) oxide (formed by heating Cd in O2, and varying in colour from green to black) adopts an NaCl structure. It is insoluble in H2O and alkahs, but dissolves in acids, i.e. CdO is more basic than ZnO. Addition of dilute alkali to aqueous solutions of Cd precipitates white Cd(OH)2, and this dissolves only in concentrated alkali to give [Cd(OH)4] (contrast [Zn(OH)4] , 21.68). Equation 21.5 showed the role of Cd(OH)2 in NiCd cells. Yellow CdS (the stable a-form has a wurtzite structure. Figure 5.20) is commercially important as a pigment and phosphor CdSe and CdTe are semiconductors (see Section 22.2). 

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