crystal phase change is called polymorphism. “Under

crystal lattice structure explains why ice deep in a glacier is sometimes
transparent and warmer than the ice at the surface. Bridgman contin?ued to improve his pressure vessel. Replacing the steel piston with one
made of a newly developed substance called carboloy, an alloy formed
from cementing a fine powder of tungsten carbide with cobalt, he could
expand his range to 50,000 atmospheres of pressure. By making the pres?sure vessel and the pistons of carboloy and emerging the whole thing in
liquid, he was able to reach 100,000 atmospheres of pressure on material
measuring a few cubic millimeters in volume. Ultimately, he would reach
400,000 atmospheres.
Bridgman found that such extreme pressures changed the crystal
lattice structure for many types of materials, creating in a way new
materials from the same molecules. This type of phase change is called
polymorphism. “Under pressure, polymorphism is a very common phe?nomenon; the number of instances increases with increase in the experi?mental pressure range and with increasing sensitiveness in the methods
for detecting small discontinuities of volume.