A transition in which the molar @G02629@ (or @C01032@) and its \((n - 1)\)th-order derivatives are continuous, whereas the \(n\)th-order derivatives with respect to temperature and pressure are discontinuous at the transition point.
first-order phase transition
second-order transition
PAC, 1994, 66, 577. (Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)) on page 587 [Terms] [Paper]