Domain pattern formation in ferroelastic Pb-3(PO4)(2) by computer simulation

A model of lead phosphate, which describes the rhombohedral-monoclinic phase transition, is used to form domain patterns in the annealing process. The obtained domain structures show W and W' types of domain walls in agreement with the stress-free laws proposed in Sapriel's theory. The observed W domain walls are parallel to the ternary symmetry axis, while the W' ones are tilted with respect to the same axis. The antiphase domain walls take no preferential orientations, and remain parallel to the ternary axis. The calculated density of the potential energy of the domain wall of type W is estimated to be E-dw = 49 K/A(2) at T = 300 K.