Eigenfehlordnung in Kristallen

Crystals in thermodynamic equilibrium at finite temperature exhibit deviations from ideal periodicity, which are called “thermodynamic defects” (“Eigen-defects”). The various types of thermodynamic defects are discussed and their concentration for thermodynamic equilibrium statet. According to the various types of feed-back among the defects (cooperativity of thermodynamic disorder) with a variation of temperature the thermodynamic disorder may cause phase transitions of first or higher order.