temperaturplateauer

Temperaturplateauer, or temperature plateau, is a concept in thermodynamics describing a range of temperatures during which a system’s temperature remains nearly constant while heat is added or removed. This behavior commonly occurs during phase transitions at a fixed pressure, because the incoming or released energy goes into changing the phase rather than raising the temperature.

During a plateau, the system typically contains a mixture of phases (for example solid and liquid). The temperature equals the equilibrium temperature of the phase boundary (the melting or boiling point). The heat input or removal is primarily latent heat, so the relation dQ = L·dm applies, with dT ≈ 0.

Common examples include the melting of ice at 0°C and the boiling of water at 100°C under one atmosphere. For pure substances at constant pressure, plateaus occur at the characteristic transition temperatures. Impurities, pressure changes, or finite heat transfer rates can broaden or distort the plateau into a sloped region.

In practice, plateaus are observed in calorimetry and heating or cooling curves. Real systems show slight slopes due to thermal resistance, nonuniform mixing, and deviations from ideal constant pressure. The width of a plateau is influenced by latent heat and sample mass.

Plateaus are used to identify phase transition temperatures and to characterize materials in calorimetric experiments, including differential scanning calorimetry (DSC). They help delineate phase boundaries in phase diagrams.