Crystalline Structures of Ice

The ice crystalline stmcture can contain many kinds of point defects, dislocations, and planar defects in common with other crystalline materials [3]. For point defects, there are several categories in ice molecular defects, impurity defects, electronic defects, protonic defects, and combined defects. Dislocations in the ice stmcture 

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As far as other physical systems are concerned, the FIR absorption has also been observed in supercooled viscous liquids and glasses (for a detailed review see Ref. 17). A similar resonance phenomenon seems to occur [17] in the crystalline structures of ice clathrates where dipolar (and nondipolar) molecules... 

FIGURE 12-5 Like all crystalline solids, the molecules in crystalline ice are well ordered in a three-dimensional pattern called the crystalline structure of ice. 

Glendenning NK (2001) Phase transitions and crystalline structures in neutron star cores. Phys Rep 342 393-447 Glendenning NK, Pei S (1995) Crystalline structure of the mixed confined-deconfined phase in neutron stars. Phys Rev C 52 2250-2253 Godderis Y, Donnadieu Y, Nedelec A, Dupre B, Dessert C, Grard A, Ram-stein G, Francois LM (2003) The Sturtian snowball glaciation fire and ice. Earth Planet Sci Lett 211 1-12... 

Figure 12.2. The structure of ice cream mix and ice cream. (A). Fat globules (F) in mix with crystalline fat within the globule and adsorbed casein micelles (C), as viewed by thin section transmission electron microscopy. (B). Close-up of an air bubble (A) with adsorbed fat, as viewed by low temperature scanning electron microscopy. (C). Air bubble (A) with adsorbed fat cluster (FC) that extends into the unfrozen phase, as viewed by thin section transmission electron microscopy with freeze substitution and low temperature embedding.

The crystal structures of many compounds are dominated by the effect of H-bonds, as, for example, in the case of the tridimensional structure of ice, the layer structure of B(OH)3, and the infinite zig-zag chains in crystalline HF. 

The water molecule has an approximately tetrahedral charge distribution, two positive charges at the positions of the hydrogen atoms (/ HOH = io41/2°) and two negative induced charges. The semi-crystalline structure of water and also the crystal structures of the modifications of ice show a similarity to... 

In the perfect crystalline structure of ordinary (hexagonal) ice, each water molecule is H-bonded to four tetrahedrally... 

The structures of the range of exotic crystalline phases of ice have been, for the most part, well known for many decades [9] and provide a suitable framework for the theoretical modelling. Moreover, by suitably choosing the... 

Fig. 7. The effect of adsorbed protein on structure of ice-cream mix, ice cream, and melted ice cream. A-B, ice-cream mix with no surfactant and with added surfactant, respectively, as viewed by thin-section transmission electron microscopy. f= fat globule, c = casein micelle, arrow = crystalline fat, bar = 0.5 pm. See Reference 24 for methodology. C-D, ice cream with no surfactant and with added surfactant, respectively, as viewed by low-temperature scanning electron microscopy, a = air bubble, f = fat globule, bar = 4 pm. See Reference 34 for methodology. E-F, ice cream with no surfactant and with added surfactant respectively, as viewed by thin-section transmission electron microscopy with freeze substitution and low-temperature embedding. a = air bubble, f= fat globule, c = casein micelle, fc = fat cluster, bar = 1 pm. See Reference 13 for methodology. G-H, melted ice cream with no surfactant and with added surfactant respectively, as viewed by thin-section transmission electron microscopy. f= fat globule, c = casein micelle, fn = fat network, bar = 1 pm in G and 5 pm in H. See Reference 24 for methodology.

Narten et al. also deduced from their data that one fifth of the water molecules are located at this additional distance. In a RDF picture, this corresponds to 4 nearest-neighbours at 2.76 A and 1 second neighbour at 3.3 A. This matches well the atomic surrounding depicted by the cluster corresponding to the structure of ice after the irradiation (cluster 2). The local order before the irradiation is better described by the 4-coordinated tetrahedron found in the normal amorphous low-density ice and in the crystalline ice (cluster 1). Thus we conclude that the structure of the ice film before the irradiation is not that of the high-density phase but that of the normal low-density phase. In addition, since the irradiated ice has a local order similar to what expected in the high-density phase, we also conclude that the photolysis at 20 K has induced the phase transition from the low-density to the high-density amorph. 

We must declare here that the entire study should be considered as a pilot project , with numerous details still to be clarified/refmed. Still, the above finding seems to indicate that an important aspect of the structure of ice Ih, represented by the measured diffuse scattering, could not be captured sufficiently well by existing models of the crystalline structure. 

Several different crystalline modifications of ice are formed under high pressure. Ice II, a kind of ice that forms at about 3,000 atmospheres pressure, has the structure shown in the adjacent drawing. 

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