POSSIBLE PHASE TRANSITION IN H2O ICE Ih NEAR 110 K

David T. W. Buckingham

Sueli H. Masunaga

Forrest C. Gile

John J. NeumeierNSF AWARD DMR-1204146

W12.07:

MOTIVATION We observed a phase transition in thermal expansion measurements of H2O ice Ih.

Structural understanding of transition glassy crystal [1].

: Heat capacity of ice divided by

temperature vs

temperature.

Samples were

subject to

different thermal

treatments. [1].

[1] Haida, O., et al., Calorimetric Study of the Glassy State X. Enthalpy Relaxation at the Glass-Transition Temperature of Hexagonal Ice,

J. Chem. Thermodynamics, 6, 815 (1974)

: Thermal expansion

coefficient of ice

vs temperature

measured along

a- and c-axes.

Inset shows

percent-change

in length at 5 K.

SLOW & DISORDERED ICE Ih

Total number, , of allowed (ice rules)

hydrogen configurations within crystal of

molecules [2]:

= 61

2

2

=3

2

Giving rise to zero-point entropy,

0 = ln3

2= 3.371 J K1 mol1

[2] Pauling, L., The Structure and Entropy of Ice and of Other Crystals with Some Randomness of Atomic Arrangement, J. Am. Chem. Soc., 57, 2680 (1935)

: The six possible orientations of hydrogen configuration around an oxygen

atom. p shows direction of electric dipole

moment of first orientation.

[3] Suga, H., Ultra-Slow Relaxation in Ice and Related Substances, Proc. Japan Acad., 81, Ser. B (2005)

: Hexagonal crystal structure of ice. Tetrahedral bonding and hexagonal

structure force highly disordered proton

configuration.

SLOW & DISORDERED ICE Ih

Total number, , of allowed (ice rules)

hydrogen configurations within crystal of

molecules [2]:

= 61

2

2

=3

2

Giving rise to zero-point entropy,

0 = ln3

2= 3.371 J K1 mol1

[2] Pauling, L., The Structure and Entropy of Ice and of Other Crystals with Some Randomness of Atomic Arrangement, J. Am. Chem. Soc., 57, 2680 (1935)

: The six possible orientations of hydrogen configuration around an oxygen

atom. p shows direction of electric dipole

moment of first orientation.

: The dielectric relaxation time of pure H2O ice Ih. Suga [3] used calorimetry and

dielectric measurements.

[3] Suga, H., Ultra-Slow Relaxation in Ice and Related Substances, Proc. Japan Acad., 81, Ser. B (2005)

THERMAL EXPANSION EXPERIMENT Capacitance-based fused quartz dilatometer [4].

Resolution:

Absolute, ~0.1 .

Relative, 10-9.

Ultrapure Milli-Q H2O = 18.2 @ 25 ,

deaerated in vacuum, zone-refined single crystals [5].

Crossed-polarized light orientation.

Measured on warming, 0.2 K/min.Vlowering < 0.4 cm/day

: Exploded view of dielectric cell.

: Assembled dielectric cell with

non-ice sample (black

piece).

: Ice samples viewed between crossed-polarizing filters. Quarter

is for size scale.

: Cross-section of single crystal growth apparatus.

[4] Neumeier, J. J., et al., Capacitive-Based Dilatometer Cell Constructed of Fused Quartz for Measuring the Thermal Expansion of Solids, Rev. Sci. Inst., 79, 033903 (2008)

[5] Bilgram, J., et al., Perfection of Zone Refined Ice Single Crystals, J. Crystal Growth, 20, 319 (1973)

16

cm

THERMAL EXPANSION RESULTS Transition in thermal expansion

coefficient, , of magnitude

105 K1 near 110 K as

measured parallel to c-axis.

No such transition as measured

parallel to a-axis.

Increase of transition

temperature, , with increase in

cooling rate.

Figure: Thermal expansion

coefficient versus temperature.

Inset shows the cooling rates of

each measurement.

Figure: Capacitance versus time. Each curve was measured at constant

temperature (5 mK).

DIELECTRIC RELAXATION EXPERIMENT

Dielectric cell made of fused quartz with Au

electrodes, BeCu springs.

Measure charge versus time at constant temperature

(5 mK) from 102 149 K.

Fit data with equation for charging capacitor:

= 1

At = 5, capacitor is 99.3% charged net dipole

moment has reached 99.3% of its maximum.

5 = dielectric relaxation time.

: Dielectric cell with ice

sample as

dielectric.

c-axis

Figure: Dielectric relaxation time versus temperature as measured by

Suga [3] and our saturated capacitance measurements.

DIELECTRIC RELAXATION EXPERIMENT

Dielectric cell made of fused quartz with Au

electrodes, BeCu springs.

Measure charge versus time at constant temperature

(5 mK) from 102 149 K.

Fit data with equation for charging capacitor:

= 1

At = 5, capacitor is 99.3% charged net dipole

moment has reached 99.3% of its maximum.

5 = dielectric relaxation time.

: Dielectric cell with ice

sample as

dielectric.

THERMALLY STIMULATED DEPOLARIZATION (TSD) CURRENT

Cool sample (0.2 K/min) in electric field. Remove

field, measure current on warming (0.2 K/min).

Molecular dipole relaxation results in release of

charge from capacitor plates current peak.

Anisotropy indicates different relaxation processes

along crystallographic axes.

Circuit diagram for TSD measurement. V=550V is

applied DC voltage, S a

switch, C is capacitor with

ice as dielectric, G the

capacitor guard ring, A the

ammeter.

TSD current versus temperature measured after electric field was applied parallel to (red) and perpendicular to (blue) the c-axis.

DEPENDENCE ON COOLING/WARMING RATE

Recall shift in dependent on

cooling rate.

DEPENDENCE ON COOLING/WARMING RATE

Recall shift in dependent on

cooling rate.

Johari & Jones observed a shift in TSD current

peak(s) near 110 K in pure polycrystalline ice

when measured with different warming rates [6].

Argue ice Ih undergoes a relaxation

phenomenon frozen-in proton configuration

relax at different T depending on warming rate.

No knowledge regarding anisotropy of effect.

[6] Johari, G. P. and Jones, S. J., Study of the Low-Temperature Transition in Ice Ih by Thermally Stimulated Depolarization Measurements, J. Chem. Phys., 62, 4213

(1975)

Figure: TSD current of pure ice

measured with different

warming rates

CONCLUSION & FUTURE WORK Transition in thermal expansion coefficient of H2O ice Ih:

Anisotropic

Glass transition associated with the freezing-in of the proton configurations.

Verified by residual entropy, s dependence on cooling rate and TSD current.

Future plans:

Measure potential anisotropy in dielectric relaxation time.

D2O and KOH-doped ice thermal expansion and dielectric properties.

THANK YOU!

QUESTIONS?