Studies in Natural and Artificial Ice

Mechanical Properties

Peak stress vs Schmid factor for high purity ice single crystals
Peak stress from vs Schmid factor at an axial strain rate of 1 x 10-5 s-1 for high purity ice single crystals.

CRSS versus the Schmid factor for high purity ice crystals
Calculated peak critical resolved shear stress, CRSS, normalized to a constant shear strain rate on the basal slip plane of 1 x 10-5 s-1 at 20°C versus the Schmid factor for high purity ice crystals.

Comparison between the engineering stress-strain curves
Comparison between the engineering stress-strain curves for pure and H2SO4-doped ice single crystals of various concentrations, with the basal plane normal at 3° to the loading direction, at an axial strain rate of 1 x 10-5 s-1 at -20°C.

Difference in CRSS (peak stress)
Difference in CRSS (peak stress), for the basal plane normal at 3° to the loading direction, between undoped ice and H2SO4-doped ice crystals (sppure - spdoped) versus the square root of the H2SO4 concentration for crystals compressed at 20°C at a shear strain rate of 1 x 10-5 s-1.

Typical resolved shear stress-strain curves at different axial strain rates
Typical resolved shear stress-strain curves at different axial strain rates (indicated) of high purity ice single crystals at 20°C.

Graph of strain rate versus CRSS
Graph of strain rate versus CRSS showing comparison between the n values of high-purity ice and H2SO4-doped ice single crystals of two different orientations.

Electrical Conductivity of Doped Ice

Preliminary studies on sulfuric acid-doped (10 p.p.m.) ice have revealed clear differences between the d.c. conductivity of the grain boundaries and of the lattice (Figure 1). A 1V potential difference was applied to the specimens using thin, spade-like platinum electrodes inserted in the ice. The specimens were incased in a metal box in order to prevent unwanted electromagnetic interference. Two set-ups were used to measure the current. First, the current was sampled at rates as high as 106 s-1 using a fast electromagnetic relay (capable of ramping up the d.c. voltage applied to the specimen rapidly and without oscillations), a signal amplifier (Femto), and a digital oscilloscope. After approximately 0.1 s the sampling rate was reduced to two samples/sec and the current was measured with a Keithley 485 picoammeter connected via a PCMCIA-GPIB+ card to a computer.

The drop in the current as a function of time is presumably due to polarization of the electrodes. This relaxation can provide information on the dielectric properties of ice.

Current as a function of time along a grain boundary and in the lattice in ice doped with 10 p.p.m. H2SO4
Figure 1: Current as a function of time along a grain boundary and in the lattice in ice doped with 10 p.p.m. H2SO4 after a 1 V d.c. potential was applied through Pt electrodes spaced 10 mm apart.

Presentation

Firn Workshop

Find out more about the Workshop on the Microstructure and Properties of Firn, March 10-11, 2008.

References

  • "Fractography of Ice", E.M. Schulson, I. Baker, C.D. Robertson, R.B. Bolon and R.J. Harnimon, Journal of Materials Science Letters, 8 (1989) 1193-1194.
  • "Dislocations and Grain Boundaries in Polycrystalline Ice: A Preliminary Study by Synchrotron X-ray Topography", F. Liu, I. Baker, G. Yao and M. Dudley, Journal of Materials Science, 27 (1992) 2719-2725.
  • "Dynamic Observations of Dislocation Sources at Grain Boundaries in Ice", F. Liu, I. Baker, G. Yao and M. Dudley, Philosophical Magazine Letters, 65 (1992) 279-281.
  • "Synchrotron X-Ray Topography of Polycrystalline Ice", F. Liu, I. Baker, G. Yao and M. Dudley, Proceedings of the 11th International Association for Hydraulic Research Ice Symposium, Banff, Canada, June, (1992) 1115-1126.
  • "Dynamic Observations of Grain Boundaries and Dislocations in Ice", I. Baker, F. Liu and M. Dudley, Proceedings of the 6th International Conference on Intergranular and Interphase Boundaries, Material Science Forum, vol 126-128 (1993), 543-546.
  • "A Compression Jig for X-ray Topography of Ice", F. Liu and I. Baker, Measurement Science and Technology, 4 (1993) 416-421.
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  • "Studies of Defect Behavior in Large-Grain, Polycrystalline Ice Using Synchrotron X-Ray Topography", M. Dudley, F. Liu and I. Baker, Molecular Crystals and Liquid Crystals, 240 (1994) 73-80.
  • "On In-Situ Study of Dislocation/Grain Boundary Interactions Using X-ray Topography and TEM", I. Baker and F. Liu, Proceedings of the Material Research Society, 319 (1994) 203-214. (Invited)
  • "In-situ Synchrotron X-ray Topographic Studies of Polycrystalline Ice", I. Baker, F. Liu, M. Dudley and D. Black, International Association for Hydraulic Research Ice Symposium, 1994, 416-425.
  • "Dislocation/Grain Boundary Interactions in Ice Ih under Creep Conditions", F. Liu, I. Baker and M. Dudley, International Association for Hydraulic Research Ice Symposium, 1994, 484-494.
  • "Dislocation Mobility in HCl-doped Ice", X. Hu, K. Jia, F. Liu, I. Baker and D. Black, Proceedings of the Material Research Society, 375 (1995), 287-292.
  • "A New Method to Characterize Dislocation Loops", F. Liu, I. Baker and M. Dudley, Proceedings of the Material Research Society, 375 (1995), 319-324.
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  • "Observation of Slip Transmission Through a Grain Boundary in Ice", K. Jia, I. Baker, F. Liu and M. Dudley, Journal of Materials Science, 31 (1996) 2373-2378.
  • "Dislocation/Grain Boundary Interactions in Ice Crystals under Creep Conditions", I. Baker, F. Liu, K. Jia, X. Hu and M. Dudley, Materials Forum, 207-209 (1996) 581-584.
  • "Dynamic In-situ Synchrotron X-ray Topographic Observations of Dislocations in Notched Ice Crystals", X. Hu, I. Baker and M. Dudley, in "Applications of Synchrotron Radiation to Materials Science", L. Terminello, S. Mini, D. L. Perry, and H. Ade (Eds.), Mat. Res. Soc. Symp. Proc., 437, (1996) p119-124.
  • "In-Situ X-ray Topographic Observations of Notches in Ice", X. Hu, I. Baker and M. Dudley, Scripta Metallurgica et Materialia, 34 (1996) 491-497.
  • "Temperature Dependence of Dislocations in Notched Ice", X. Hu, I. Baker and M. Dudley, Journal of Physical Chemistry B, 101 (1997) 6102-6104.
  • "Observation of Dislocations in Ice", I. Baker, Journal of Physical Chemistry B, 101 (1997) 6158-6162.
  • "The Orientation Dependence of the Strength of Ice Single Crystals", Y.L. Trickett, I. Baker and P.M.S. Pradhan, Journal of Glaciology, 46 (2000) 41-44.
  • "Dislocation Motion at Notch-Tips in Ice Single Crystals: Experiments and Interpretation", D. Cullen, X. Hu, I. Baker and M. Dudley, Cold Regions Science and Engineering, 31 (2000) 103-117.
  • "The Effects of Sulfuric Acid on the Mechanical Properties of Ice Single Crystals", Y.L. Trickett, I. Baker and P.M.S. Pradhan, Journal of Glaciology, 46 (2000) 239-243.
  • "The Effect of H2SO4 on the Stress Exponent in Ice Single Crystals", I. Baker, Y.L. Trickett and P.M.S. Pradhan, Deformation of Glacial Materials, Ed- A.J. Maltman, B. Hubbard and M.J. Hambrey, Geological Society, London, Special Publications, 176 (2000) 39-45.
  • "X-ray Topographic Observations of Dislocation/Grain Boundary Interactions in Ice", I. Baker, F. Liu, K.Jia, X. Hu, D. Cullen and M. Dudley, Annals of Glaciology, 31 (2000) 236-240.
  • "The Chemistry of Grain Boundaries in Greenland Ice", D. Cullen and I. Baker, Journal of Glaciology, 46 (2001) 703-706.
  • "Observation of Impurities in Ice", D. Cullen and I. Baker, Microscopy Research and Technique, 55 (2001) 198-207.
  • "Examination of Dislocations in Ice", I. Baker, Crystal Growth and Design, 2 (2002) 127-134. (Invited)
  • "Preliminary Microstructural and Microchemical Observations of Pond and River Accretion Ice", D. Iliescu, D. Cullen and I. Baker, Cold Regions Science and Engineering, 35 (2002) 81-99.
  • "Sulfate Crystallites in Vostok Accretion Ice", D. Cullen and I. Baker, Materials Characterization, 48 (2002) 263-270.