2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/27934We report the discovery of a new Twist Grain Boundary phase. This phase is characterised by a 2-dimensional undulation of the smectic C* like blocks in the form of a square lattice. We suggest that this three dimensionally modulated structure, which was not anticipated by theory, owes its origin to chiral interactions.10 pages(Latex), 9 figures(eps/gif); nvmadhu@rri.ernet.inSoft Condensed Mattertext