Theoretical investigation of the ferroelastic domain structure in cesium lead chloride in the monoclinic phase

The ferroelastic domain structure of CsPbCl₃, in its monoclinic phase, is analyzed by two theories: group symmetry and tensor method, or twinning by pseudo-symmetry. The loss of symmetry between the prototypic and the monoclinic phases is important and allows the existence of twelve kinds of domains. Theories provide a coherent description of domain pairs and a determination of the position of W and S walls.