Elastic properties of D$_2$O ices in solid-state amorphization and transformations between amorphous phases

Nonequilibrium phase transformations in D$_2$O ices, including the solid-state amorphization of ice 1$h$ (1$h$-$hda$) and the heating-induced transition cascade $hda$-$lda$-1$c$-1$h$ from high-density amorphous ($hda$) ice to low-density amorphous ($hda$) ice followed by crystallization in cubic ice 1$c$ and phase transition to ordinary hexagonal ice 1$h$, were studied using an ultrasonic technique. It has been shown that, as in H$_2$O ice, the softening of a crystal lattice or an amorphous network precedes nonequilibrium transformations. However, noticeable isotopic differences in the behavior of the elastic properties of H$_2$O and D$_2$O, in particular, their $1h$ and $hda$ modifications, call for a more detailed study of the structural features of these H$_2$O and D$_2$O phases.