DOMAIN-STRUCTURE EVOLUTION AND CRYSTALLOOPTICAL PECULIARITIES OF INCOMMENSURATE FERROELASTIC KSC(MOO4)(2)

Investigations of domain structures crystallomorphology and evolution in all of three ferroelastic phases of KSc(MoO4)(2) have been performe d. Besides, the disposition of optical indicatrix axes n(g), n(m) was established (by microconoscope technique) and the birefringence was me asured (by improved Senarmont method) with strict domain structure con trol. It was confirmed that all three phases exhibit 2/m macroscopic s ymmetry and that the spontaneous optical anisotropy in phase III has t ile opposite sign relative to the one in II and IV phases. Possible na ture of the transitions between monoclinic phases has been discussed.