Fig. 2: Changes in the crystal structure and crystal size and shape during the phase transition.
From: Exceptionally high work density of a ferroelectric dynamic organic crystal around room temperature
a Comparison of the unit cells before and after the phase transition. The values of the characteristic unit cell parameters in the two phases are given. The doubling of the c axis that occurs during the transition from form I to II is not shown here. b, c Cartooned crystal habits of form I (b; 250 K) and form II (c; 310 K) shown with molecular orientation in form I (b) and form II (c) crystals viewed in the [001] and [100] directions. Upon heating from 290 to 310 K, the distance between the adjacent sheets containing nitrate and guanidinum ions increases from 3.605 to 3.749 Å while the adjacent hexameric layers are apparently twisted in respect to each other. d Changes in the unit cell parameters of form I before and during the reversible phase transition. e Cyclability of a good-quality single crystal over the phase transition monitored by the change in its length. The expansion and shrinkage of the crystal were recorded over 20 thermal cycles.
