Inhibition of the phase transition in CsLiSO4 induced by uniaxial pressure

This work presents for the first time a measurement on inhibition of the ferroelastic phase transition in CsLiSO4 crystals at temperature 202 K. The result is obtained by application of uniaxial pressure up to 1 kbar. which is directed along the [010] axis relative to the orthorhombic structure. Stabilization of the monoclinic phase is found due to the fact that the soft TA phonon becomes uncoupled to the hard TO phonon and does not approach to zero at 202 K. Therefore, the behavior of the dielectric constant ε2 exhibits a normal dependence on the temperature. We have performed a simple theoretical analysis to calculate the TA and TO phonon energies. From these results the uniaxial pressure - temperature phase diagram of CsLiSO4 is determined.

Keywords:

• CLS
• ferroelasticity
• phase transition
• uniaxial pressure

Notes

Universidade de Brasilia, Brasilia - DF, Brazil