Yes, oxygen can be crystallized. It exists in a solid, crystalline state under specific conditions, primarily at very low temperatures or extremely high pressures.
Understanding Solid Oxygen
While we commonly encounter oxygen as a gas, it can transition into a solid form, often referred to as solid oxygen or crystalline oxygen. This state is achieved when oxygen molecules are arranged in an ordered, repeating structure, similar to how other elements and compounds form crystals.
Phases and Properties of Crystalline Oxygen
Solid oxygen exhibits several different crystalline phases depending on the temperature and pressure conditions. These phases can have distinct colors and optical properties. For instance, at moderate pressures, crystalline oxygen appears as a light blue transparent solid.
Remarkably, applying increasing pressure drastically alters its characteristics:
- Initial State: A light blue, transparent crystal.
- At Approximately 10 GPa: The crystal undergoes a phase change, turning orange and then red.
- At Around 40 GPa: With further compression, the crystal becomes noticeably darker, eventually appearing nearly opaque to visible light.
This demonstrates the fascinating transformations oxygen undergoes when its molecules are forced into denser, more tightly packed arrangements under extreme pressure.
Achieving Crystallization
Oxygen typically crystallizes at temperatures below its melting point of approximately -218.79 °C (-361.82 °F) at standard atmospheric pressure. However, as noted, high pressure also plays a crucial role in forming and transforming various crystalline phases of oxygen, even at temperatures where it would normally be a gas or liquid. Scientists use specialized equipment, such as diamond anvil cells, to achieve the immense pressures required to study these high-pressure solid phases.
To learn more about the different forms oxygen can take, you can explore information on the phases of matter.