A @S05531@ or @H02822@, in which the @H02753@ shows either a discontinuity (second-order) or a vertex (higher-order) at the transition temperature. Example: The transition at \(846\ \text{K}\), accompanied by a finite change in @S05800@ at constant pressure \(C_{p}\), of the low-temperature polymorph of quartz to the high-temperature polymorph.