Uniaxial pressure effect on the phase transition of mixed DTGS-TGS crystals

Abstract

Uniaxial pressure influence on the phase transition of deuterated (0-90%) TGS crystals are reported for the three directions- a, b, c*. The coefficients γ_i (γ_i ≏ ∂T_c/∂x_i) are established to be lineary dependent on the uniaxial pressure. The coefficient ξ of the fourth power of P in the free energy expansion is practically uniaxial pressure independent. The main changes of γ_i observed in the ac* plane are related to “long” O-H-O and N-H-O bonds. The values of the γ_i coefficients are in well agreement with those calculated from the Ehrenfest relation.