Ferroelastic domain structure of (NH₄)₃H(SeO₄)₂and its deuterated analogue

Abstract

Abstract The effect of deuteration on ferroelastic-ferroelastic phase transitions and ferroelastic domain structure in (NH4)3H(SeO4)? was investigated. Crystals of various degrees of deuteration were studied. The temperature width of ferroelastic triclinic phase was found to decrease with increasing degree of deuteration. The temperature of superionic (2) - ferroelastic (1) phase transition lowered from 306 K for the non-deuterated crystal to 293 K for the crystal with the highest degree of deuteration. Additional result of deuteration was a change in the pattern of domain structure in the ferroelastic (1) - ferroelastic (2) phase.