Interfaces between honeycomb foams: Defect content and behaviour under deformation

We have studied the interfaces between two monolayer honeycomb foams with the same and with (slightly) different sizes and various misorientations, prepared with a special device. Several defect structures are possible for given interface parameters, but all interfaces contain exclusively 5/7 bubble pairs in one or two families, with the five-sided cells on the side of the smaller area honeycomb. We predict the dislocation content of the interfaces (Burgers vectors and spacing of defects) based on a purely geometrical-topological model in which we form the boundary by connecting dangling edges on the initially separated crystal surfaces. We deformed the bicrystals and observed the glide of lattice and interfacial dislocations and the associated changes in the defect structure of the interfaces.