Analysis of linear defects in triply incommensurate phase of quartz-type

Abstract
We analyze linear defects which are possible in the incommensurate phase of quartz type, in the case of a triple modulation. The results are shown in the domain texture approximation, but do not depend on it. Rules concerning associations of defect lines are presented, together with simple cases of loops formed with the lines. It is shown that such loops can govern nucleation processes within the incommensurate phase, to give rise to new values of the modulation wave vector k and θ (the angle characterizing the direction of the k's). These results are briefly discussed in comparison with experiments.