From Online Dictionary of Crystallography

Morphotropie (Fr). Morphotropie (Ge). Морфотропия (Ru). Morfotropismo (It). 類形 (Ja).

Following Paul Heinrich von Groth's definition, morphotropism, or morphotropy, is the change of a crystal structure produced by isomorphic substitutions. The special case in which these substitutions do not modify the crystal structure is called isomorphotropism. The latter is today more commonly known as isomorphism.

IUPAC defines a morphotropic transition as 'an abrupt change in the structure of a solid solution with variation in composition'.


  • Rinne, F. (1921). Die Kristalle als Vorbilder des feinbaulichen Wesens der Materie. Borntraeger, Berlin. English translation: Crystals and the fine-structure of matter (translated by Walter S. Stiles), New York: E.P. Dutton and Co., 1922.
  • Kálmán, A. (2005). Acta Cryst. B61, 2005, 536-547. Morphotropism: link between the isostructurality, polymorphism and (stereo)isomerism of organic crystals
  • Clark, J. B. et al. (1994). Pure App. Chem. 66, 577-594. Definitions of terms relating to phase transitions of the solid state