THE PHASE-BOUNDARY AND THE DOMAIN-STRUCTURE IN FERROELASTIC K2CD2(SO4)(3)

In this paper we present results of investigations of the phase bounda ry dynamic and domain structure in ferroelastic K2Cd2(SO4)(3). The ori entation of the phase boundary is determined as (100) and can be expla ined on the basis of Boulesteix approach and takes into account that t he lattice parameters b approximate to c approximate to a(0) at the ph ase transition point. The phase boundary has diffuse character. The de pendence of the phase boundary velocity on the heating and cooling rat e is linear. It was found that the ''forbidden'' domain structure does not appear in thin crystals (d = 0.26 mm); it appears only near the p hase boundary in crystals with thickness d = 0.66 mm and exists in a n arrow temperature region below T-c in crystals with thickness d = 1 mm . The domain walls in K2Cd2(SO4)(3) cannot be classified as W or W' do main walls.