Phase P,T-diagram of incommensurate ferroelastic Cs2CdBr4

The P,T-phase diagram of crystals Cs2CdBr4 by the method of optical double refraction is studied. A specific critical point, which is, in fact, a ternary point separating paraelastic and segnetoelastic and incommensurate states, is detected on the phase diagram in the temperature range 235≤T≤260 K and pressures 20≤P≤100 MPa. The crystals studied are the first illustration of proper incommensurate ferroelastics, in which such a point is detected