Quasi-hexagonal

Fig. XVI-8. (a) The quasi-hexagonal surface structure of clean Pt(lOO) surface, (b) Adsorption of CO lifts this reconstruction to give the structure corresponding to the termination of (100) planes (from LEED studies). [Reprinted with permission from G. Ertl, Langmuir, 3, 4 (1987) (Ref. 56). Copyright 1987, American Chemical Society.]...

Figure 6.1 Atomically resolved STM image of a thin Al203 film on NiAI(l 1 0), taken at 4 K with U = 500mV, /=1 nA (58Ax40A). All atoms exhibit a quasi-hexagonal coordination, where the three characteristic directions are marked with arrows. The unit cell was determined from the repetition of atoms. Here, gray-filled circles mark the most prominent atomic features,...

Figure 4.2 Quasi-hexagonal dislocation loop lying on the (111) glide plane of the diamond crystal structure. The <110> Burgers vector is indicated. A segment, displaced by one atomic plane, with a pair of kinks, is shown a the right-hand screw orientation of the loop. As the kinks move apart along the screw dislocation, more of it moves to the right.

The hexaboride crystal structure is related to the CsCl structure so by analogy the glide planes are (100) and the glide directions are (100). At the cores of glide disloca-tions the structure becomes quasi-hexagonal. 

Molecules of anthracene consist of three shared quasi-hexagonal rings of carbon (14C-atoms) plus ten H-atoms attached to ten of the carbons (Figure 12.1). In three dimensions the anthracene molecules have the shape of elongated tablets. They stack in crystals side-by-side in a staggered pattern to form sheets which pack together in herringbone arrays. 

III. Quasi-hexagonal Close-packing of X(X%) in the FeS2—m Type. 91... 

Cuesta and Kolb [52] have studied bromide adsorption on Au(lOO) electrodes using in situ STM. Two quasi-hexagonal structures were found, which was in agreement with the previously published SXS data. 

Fig. 4.8 Theoretical model of the (1 x 5) reconstructed surface of Ir (001). Six [110] atomic rows squeeze into 5 row-spacings of the (1 x 1) structure, resulting in a quasi-hexagonal, or pseudo-hexagonal, atomic arrangement with buckled [110]...

Fig. 4.11 The quasi-hexagonal atomic arrangement of a reconstructed layer can be found by mapping of the position of each of the atoms in the layer when the layer is slowly field evaporated.

An example of such order is shown by the hexagonal symmetry of SBS as revealed by LAXD, electron microscopy and mechanical measurements. In composite materials the choice of phase is at the disposal of the material designer and the phase lattice and phase geometry may be chosen to optimise desired properties of the material. The reinforcing phase is usually regarded elastically as an inclusion in a matrix of the material to be reinforced. In most cases the inclusions do not occupy exactly periodic positions in the host phase so that quasi-hexagonal or quasi-cubic structure is obtained rather than, as in the copolymers, a nearly perfect ordered structure. 

Miller, A., and Tochetti, D. (1981). Calculated X-ray diffraction pattern from a quasi-hexagonal model for the molecular arrangement in collagen. Int. J. Macromol. 3, 9-18. 

The adduct consists of quasi-hexagonal-packed mixed stacks of alternating donor and acceptor molecules3. 

Fig. 16 a The quasi-hexagonal guanidinium sulfonate (GS) hydrogen-bonded array, b The shifted ribbon GS array [208]... 

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