Classification and Definition of “Soft Crystals”

Abstract

Abstract“Soft crystals” typically undergo structural transformations in response to weak stimuli while maintaining the crystalline structural order. These transformations are often manifested as visible phenomena, such as changes in optical properties (color and/or luminescence color). In this chapter, the structural order, activation energy, and softness of “soft crystals” are compared with those of conventional hard crystals and soft materials, including liquid crystals and gels. Based on the results of this comparison, “soft crystals” are defined more precisely.