9.10: TLS twinning
TLS (Twin Lattice Symmetry) twinning is a term employed to indicate twinning where the twin lattice does not possess a pseudo-symmetry, differently from what happens in TLQS twinning.
In TLS twinning, the lattice row / lattice plane [ uvw ] / ( hkl ) defining the cell of the twin lattice are mutually perpendicular. When this perpendicularity is imposed by the symmetry of the lattice, one speaks of intrinsic-TLS ( i-TLS ). In all other cases, the conditions of perpendicularity, depend on one or more metric parameters: one then speaks of extrinsic-TLS ( e-TLS ).