Often characterized as glass, amorphous ice had long been known to appear in either a low-density amorphous (LDA) or high-density amorphous (HDA) state. A recent study demonstrated the existence ...

Amorphous Si shows an irreversible sharp transition to an amorphous metallic phase near 16 GPa. At 77 K, amorphous ice changes from its low-density to high-density polyamorph under pressure in a ...