When the density of these crystals is reduced, they "melt" into a disordered liquid, just as ice melts into water.
(the density of these crystals; is reduced; ) (they; melt; into a disordered liquid; T:When the density of these crystals is reduced)
the density of these crystals they
is reduced melt
into a disordered liquid T:When the density of these crystals is reduced