Equation of state of ordinary ice Ih at 145 K under true hydrostatic pressure up to 5 kbar.

Neutron diffraction in combination with a gas pressure cell device allowed us to measure the lattice parameters of ordinary ice (D2O ice Ih) up to 5 kbar at 145 K under true hydrostatic pressure conditions. The results are compared with earlier studies and may reveal a more precise equation of state of ice Ih at 145 K. The elastic anisotropy was found to be very small in accordance with the very small anisotropy of thermal expansion. Nitrogen was used as the pressure medium, for which it is shown here that under the above experimental conditions no clathrate hydrates are formed