Temperature–Pressure Phase Diagram for Rb2ZnCl4 Crystals

We have studied the effect of uniaxial stress along the principal crystallophysical directions on the temperature variations in the birefringence Δn i and the refractive indices ni for Rb2ZnCl4 crystals in the region of phase transitions from the paraelectric phase to the incommensurate phase and then to the commensurate ferroelectric phase. We have established that Δn i and n i are rather sensitive to the action of uniaxial stresses. We have observed a significant pressure-induced shift of the paraelectric – incommensurate – ferroelectric phase transition points in different temperature regions, depending on the direction of the uniaxial compression.