containerless

Containerless refers to processes and analyses in which a material is treated, measured, or stored without physical contact with a container. The goal is to avoid contamination from container materials and to access conditions that are difficult or impossible in contact with walls, such as high temperatures, reactive chemistries, or significant undercooling.

Common containerless methods include electromagnetic levitation (EML), which uses alternating magnetic fields to suspend and heat conductive samples; electrostatic levitation (ESL), which uses electrostatic forces to levitate charged samples and permits measurement of high-temperature liquids and undercooled solids; and aerodynamic levitation (ADL), where a gas jet supports the sample while it is heated, often by a laser. These techniques create crucible-free environments and can maintain samples in a near-void or controlled atmosphere.

Applications include the study of thermophysical properties of molten metals and alloys (density, viscosity, surface tension), glass formation and crystallization kinetics, and the investigation of metastable or highly reactive materials. Containerless processing supports undercooling experiments, enabling the investigation of phase transitions, nucleation, and the formation of amorphous or unusual crystalline phases without heterogeneous nucleation from container walls.

Advantages include reduced contamination, allowing higher purity measurements; avoidance of crucible reactions; access to extreme temperatures and reactive chemistries; and enhanced control of atmospheric composition. Challenges include small sample sizes, complex instrumentation and control systems, sensitivity to external disturbances, difficulty in making certain measurements, and higher cost and maintenance.