In ice single crystals

DISLOCATION PATTERNING AND DEFORMATION PROCESSES IN ICE SINGLE CRYSTALS DEFORMED BY TORSION... 

In summary, torsion creep tests on well-oriented ice single crystals appear to be a pertinent experiment to try to understand and represent the fundamental mechanisms of deformation in ice single crystals. The presented evidence for the occurence of cross-slip as a rate-limiting process questions the role of dislocation climb as suggested by Louchet (2004) I... 

Surface conductive effects in snow were investigated by Kopp (93) who found that conductivity and activation energy were larger than expected from its ice content. Blicks, Egger, and Riehl (8) investigated surface conductive effects in ice single crystals. They found a higher concentration of impurities at the ice surface. Bullemer and Riehl (15) found the same temperature dependence (8.5 kcal./mole) for the bulk conductivity of pure and HF-doped ice. 

Below the fim layers normal self diffusion in ice single crystals is expected to take over. In order to solve equation (5) at greater depths we follow a layer from its transformation to ice and use a coupled temperature ice flow model (Johnsen et al., 1995a) to obtain the temperature and strain rate history ez(t) of the layer together with the self diffusion constants measured by Ramseier (Ramseier, 1967) from the modelled in-situ temperature. 

The early observation of macroscopic slip lines in deformed ice single crystals by Nakaya (1958) or Readings and Bartlett (1968)" indicated the simultaneous and correlated motion of many dislocations. More recently, acoustic emission analyses performed on ice single crystals during deformation revealed the scale-free intermittent motion of dislocations through dislocation avalanches. 

Figure 1 Typical creep cui e of an ice single crystal deformed in torsion up to 7 Vo along the c-axis. The deformation is the measured shear strain on the surface.

Usually, creep deformation of ice single crystals is associated to a steady-state creep regime, with a stress exponent equal to 2 when basal glide is activated . In the torsion experiments performed, the steady-state creep was not reached, but one would expect it to be achieved for larger strain when the immobilisation of the basal dislocations in the pile-ups is balanced by the dislocation multiplication induced by the double cross-slip mechanism. 

Fig. 8.10. Stress-strain curves for ice single crystals deformed by basal shear at constant strain rate. In (a) the temperature is — is °C and the strain rate is given as a parameter in units of lO" s , while in (6) the strain rate is 1-3 x io s and the temperature is varied (Higashi et al. 1964).

K. Kobayashi, M. Koshino, K. Suenaga, Atomically resolved images of 1(h) ice single crystals in the solid phase. Phys. Rev. Lett. 106(20), 206101 (2011)... 

Ih ice single crystals were grown heteroepitaxially on a cleaved 0001 face of an Agl crystal from supersaturated water vapor in a nitrogen environment The temperature of the ice single crystals (Tg pi ) was set at —15.0°C, at which temperature basal ( 0001 ) faces of ice crystals grow most widely [8]. To supply water vapor to the sample ice crystals, other ice crystals were prepared (as a source of water vapor) on a copper plate that was set 16 mm from the Agl crystal, and then the temperature of the source ice crystals was separately set at—13.0 °C. By... 

Furukawa, Y. and Kohata, S. (1993) Temperature dependence of the growth form of negative crystal in an ice single crystal and evaporation kinetics for its surfaces. J. Cryst. Growth, 129 (3-4), 571-581. 

In order to anticipate the behavior of an ongoing experiment, we made our first calculations in an idealized geometry (Wettlaufer and Worster 1995). Soon thereafter Larry Wilen and Greg Dash (1995) observed premelting dynamics at ice single crystal interfaces formed against a flexible polymer membrane with a more complicated ge-... 

Finnegan, W. G., and R. L. Pitter, Ion-Induced Charge Separations in Growing Single Ice Crystals Effects on Growth and Interaction Processes, J. Colloid Interface ScL, 189, 322-327 (1997). 

Fig. 5.9 Ne field ion images of a GP[1] zone emerging from a (024) plane of an Al-4 wt% Cu alloy. This alloy was grown by Bridgeman method. After a homogenizing treatment at 793 K for 1.7 x lOf5 s, single crystal samples with a longer axis parallel to [001] were prepared. They were quenched into ice water and then aged at 403 K for 6 x 104 s under the tensile stress of 73.5 MPa along the [001]. Between a and b, 11 (024) layers were field evaporated, and between b and c, 16 more layers were evaporated. The distance between two Cu atoms should be 9.06 A as is shown in d. (Courtesy of M. Wada.)...

Abstract—Low frequency lines in the Raman spectrum of single crystals of formic acid and ice are interpreted as arising from the vibrations of the hydrogen bond H.O. 

Powdered single crystals of 1 (ca. 20 mg) were sandwiched between two Pyrex cover glasses and placed in a polyethylene bag, which was irradiated with a 400-W high-pressure mercury lamp for 6 h (3 h for each side of the sample) in an ice-water bath. Out of seven carboxamides examined, la, le and lg showed intramolecular photocycloaddition in solid state to give the [4+4] cycloadducts 2a, 2e, and 2g in an almost quantitative yield after complete conversion, and If gave 2f in 9% yield. 

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