title: Tilt grain boundary instabilities in three-dimensional lamellar patterns.
abstract: We identify a finite wave-number instability of a 90 degrees tilt grain boundary in three-dimensional lamellar phases which is absent in two-dimensional configurations. Both a stability analysis of the slowly varying amplitude or envelope equation for the boundary, and a direct numerical solution of an order parameter model equation are presented. The instability mode involves two-dimensional perturbations of the planar base boundary, and is suppressed for purely one-dimensional perturbations. We find that both the most unstable wave numbers and their growth rate increase with epsilon , the dimensionless distance away from threshold of the lamellar phase.
authors.affiliation: McGill Institute for Advanced Materials and Department of Physics, McGill University, Montreal, Canada.
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Huang
authors.forename: Jorge
authors.initials: J
authors.lastname: Viñals