Yikang Yu

Naturally Dried Graphene Aerogels with Superelasticity and Tunable Poisson's Ratio.

A novel natural drying (ND) strategy for low-cost and simple fabrication of graphene aerogels (GAs) is highlighted. The as-formed NDGAs exhibit ultralarge reversible compressibility (99%) and tunable Poissons ratio behaviors (-0.30 < ν < 0.46), which suggests promising applications in soft actuators, soft robots, sensors, deformable electronic devices, drug release, thermal insulator, and protective materials.

Hyperbolically Patterned 3D Graphene Metamaterial with Negative Poisson's Ratio and Superelasticity.

A hyperbolically patterned 3D graphene metamaterial (GM) with negative Poissons ratio and superelasticity is highlighted. It is synthesized by a modified hydrothermal approach and subsequent oriented freeze-casting strategy. GM presents a tunable Poissons ratio by adjusting the structural porosity, macroscopic aspect ratio (L/D), and freeze-casting conditions. Such a GM suggests promising applications as soft actuators, sensors, robust shock absorbers, and environmental remediation.

Structure and magnetic properties of magnetron-sputtered FePt/Au superlattice films

Using dc magnetron sputtering, FePt/Au multilayer films were prepared, and the effects of Au thickness and annealing temperature on structure and magnetic properties of the FePt/Au films were investigated. The as-deposited FePt/Au multilayer films with a thicker Au layer show a superlattice structure. The interatomic layer spacing d(2 2 0) in face centered cubic (fcc) FePt lattice increases with increase in Au thickness. Accordingly, the strain energy stored in the fcc FePt lattice increases. After annealing at 300 °C, ordered FePt films were obtained, and the in-plane and out-of-plane coercivities of the films were found to increase with the increase in the Au layer thickness. When the Au layer thickness is 3.5 nm, the in-plane and out-of-plane coercivities of the films can reach 2.08 kOe and 1.56 kOe, respectively. The strain energy stored in fcc FePt lattice is responsible for the lower temperature ordering of FePt phase. For the films annealed at high temperature, the thicker Au layer in the films restrained the ordering of the FePt phase, which leads to the decrease in the coercivities of the films with increasing Au thickness.

Fluidic behaviours in a 2D folded-graphene aerogel monolith

Conduction of pressurized water through two-dimensional (2D) layers in monolithic folded-graphene aerogels (FGA) is investigated experimentally. The synthesized FGA has a regular layered structure with a uniform d-spacing around 20 nm. Compared with one-dimensional nanofluidics in carbon nanotube arrays that have a similar characteristic length scale, the conduction pressure of FGA is much lower by nearly 2/3. The reduction in pressure may be attributed to the more energetically favourable molecular configurations in the 2D nanoenvironment, associated with the relaxation of lateral constraints of water molecules. The water conduction pressure through FGA rises exponentially with the sample thickness, due to the interlayer resistance. This finding may find wide applications in nanotransportation, nanofiltration, and nanofluidic energy management.