transientliquid

Transientliquid is a term used to describe a short-lived, liquid-like state that can arise during non-equilibrium processes, existing only for a finite time before transforming into a more stable phase. It is not a widely standardized phase of matter, but rather a concept used to capture fluid-like behavior observed briefly under rapid changes in temperature, pressure, or composition. The term emphasizes the transient nature of the state and its departure from conventional liquids and solids.

Formation and context: A transientliquid can form during rapid heating or melting, energetic deposition, high-strain-rate deformation, or ultrafast cooling, where a fluid-like arrangement emerges before crystallization, vitrification, or segregation occurs. In nanoscale systems or under extreme confinement, crystallization may be suppressed long enough to allow a transient liquid to exist. In laser–matter interactions or shock events, a surface layer may briefly behave as a liquid despite global solidification elsewhere.

Characteristics: Transientliquids exhibit some liquid-like properties, such as diffusion and flow, but their structure and dynamics are non-equilibrium and not stable over long timescales. Their lifetimes can range from femtoseconds to microseconds or longer, depending on the material, energy input, and observation method. They may show atypical rheology and rapid evolution as they relax toward a stable phase.

Observation and study: Detection often relies on time-resolved techniques such as ultrafast spectroscopy, time-resolved diffraction, pump-probe electron microscopy, or rapid calorimetry, which can capture processes occurring on very short timescales.

See also: metastable phase, supercooled liquid, quasi-liquid layer, transient phenomena, phase transition.