Wurzite structure

The Transition to the Sphalerite Structure.—The oxide, sulfide and selenide of beryllium have neither the sodium chloride nor the cesium chloride structure, but instead the sphalerite or the wurzite structure. The Coulomb energy for the sphalerite arrangement is... 

Sodium chloride structure Sphalerite or wurzite structure... 

The prediction may be made that the still unstudied crystal magnesium telluride, with the radius ratio 0.29, has the sphalerite or wurzite structure rather than the sodium chloride structure. 

It is also shown that theoretically a binary compound should have the sphalerite or wurzite structure instead of the sodium chloride structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of beryllium conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such tetrahedral crystals are particularly apt to show deformation, and it is suggested that this is a tendency of the anion to share an electron pair with each cation. 

ZnO with a polar hexagonal wurzite structure can be described as being due to the hexagonal close packing of the... 

The formula at Eq. (4-28) applies to the wurtzite structure if nearest neighbors form a regular tetrahedron (the ideal axial ratio). We see this by observing that the same answer would have been obtained in the zincblende structure with a field along a [111] direction, and that one can go from the zincblende to the wurzite structure with bond rotations all made around that [111] axis. 

In addition to the CsCl structure, 8-8 coordination, and the NaCl structure, 6-6 coordination, there are two structures having 4-4 coordination, the cubic ZnS (zinc blende) structure and the hexagonal ZnS (wurzite) structure (Fig. 27.9a and b). Note that the zinc blende structure is an fee array of sulfide ions. There is a tetrahedrally coordinated hole at each corner of the cube the zinc ions occupy four of the eight tetrahedral holes. In wurzite, the sulfide ions form an hep array, and the zinc ions occupy half of the tetrahedral holes (Fig. 27.9c). 

Werner s coordination theory, 1, 6 Whewellite structure, 6, 849 Wickmanite structure, 6, 849 Wilkinson s catalyst, 6, 239 Wilson s disease, 5, 721 copper, 6,648 removal, 6,769 copper complexes, 2,959 copper metabolism, 6,766 radiopharmaceutical agents, 6,968 Wolfram s red salt, 5,427 Wurzite... 

The radius ratios for sphalerite and wurzite type crystals with eighteen-shell cations do not conform to our criterion, so that some other influence must be operative. Without doubt this is deformation. Here again it is seen that the tetrahedral structure is particularly favorable to deformation, for the observed Zn++—O distance (1.93 A.) is 0.21 A. shorter than the theoretical one, while in cadmium oxide, with the sodium chloride structure, the difference is only 0.01 A. 

The compound ZnGa2S4 has a crystal structure which is closely related to the blende type (14). There is no appreciable range of composition for this compound. Two extensive homogeneity regions are observed, at elevated temperatures, one of the wurzite type near ZnS and the other of the blende type near Ga2S3. 

From Fisher Properties Wurzite-type structure, confirmed by XRD, BET specific surface area 14 mVg, particle diameter 4 pm [318, 1221]. 

Formula weight 191.37. Dark-red powder, d (x-ray) 5.767. Crystal structure type B3 (zincblende type) and B4 (wurzite type). 

The compounds in Table 9 are essentially derivatives of the general formula IV3V4 (Si3N4). They have the zinc blende and wurzite related structures provided their heats of atomization do not exceed approximately 61 kcal/g-atom. When their heats of atomization become greater than this value, they acquire the phenacite structure in which there is a significant deviation from the sp -lype bonding. 

Why do zinc blende and wurzite have different structures when both are ZnS Why does GaAs have one structure and AIN have the other ... 

Steps on MgO, wurtzite, and rutile surfaces are shown in Figures 13.23. The steps on the MgO show theoretically predicted displacements at the step. [Since there is a periodic set of steps, this surface could be called the (501) surface.] The special feature of the steps on the wurzite surface is the presence of the dangling bonds, which are localized at the step. The rutile surface shows that even when the surface is modeled using hard spheres, the structure of the steps depends on their orientation. [These two vicinal surfaces could be called (223) and (443).]... 

Stuke (1970) noticed that the intensity of the E2 peak in the spectra of ZnS depends on the crystallographic modification (zincblende or wurzite) much more than the Ei peak. He suggested that the E2 peak which dominates the spectra of crystalUne tetrahedral semiconductors is much more sensitive to the long-range order than the Ej peak. In his interpretation, this effect is the reason of the shift of the maximum of the absorption band towards the Ei peak observed in the amorphous forms. Ortenburger et al (1972) calculated the band state densities and 2 for a hypothetical hexagonal structure of Ge, and observed a shift of E2 towards smaller energies. 

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