Ultrasonic study of solid-phase amorphization and polyamorphism in an H$_2$O–D$_2$O (1: 1) solid solution

The elastic moduli and volume of H$_2$O–D$_2$O (1: 1) isotopically mixed ice (solid solution) have been studied at the solid-phase amorphization of normal $1h$ ice under compression at a temperature of $77$ K and at the transition from high-density amorphous ice to low-density amorphous ice with subsequent successive crystallization to cubic ($1c$) and hexagonal ($1h$) ice at isobaric ($0.05$ GPa) heating. Comparison of the results with the respective data for H$_2$O and D$_2$O ices indicates that the observed concentration (in the isotopic composition) dependences of the elastic moduli and their derivatives for different phases of ice at isotopic hydrogen substitution in the H$_2$O, H$_2$O-D$_2$O (1: 1), and D$_2$O chain can be both monotonic and significantly nonmonotonic.