Volume 14 Issue 3, March 2015

In the aftermath of a nuclear reactor accident, understanding the release of fission products from the fuel is key.

To design reliable and safe geological repositories it is critical to understand how the characteristics of spent nuclear fuel evolve with time, and how this affects the storage environment.

The incident at Fukushima Daiichi brought materials in the nuclear industry into the spotlight. Nature Materials talks to Tatsuo Shikama, Director of the International Research Centre for Nuclear Materials, Institute for Materials Research, Tohoku University, about the current situation.

The finding of a sharp interface between a chemically attacked surface and the pristine bulk in a borosilicate glass is at odds with the widely held diffusion-based mechanisms of glass durability.

Lattice distortions can be used to manipulate surface states in topological crystalline insulators. This discovery suggests new methods to control the motion of electrons in 2D electron systems.

A powerful strategy to leverage and combine the optoelectronic characteristics of different 2D materials is to stack them into vertical van der Waals heterostructures. This approach is now used to realize efficient light-emitting devices.

A theory explains the role of curvature in controlling wrinkle patterns on elastic shells.

Cracks in stretched epithelial tissue are caused by a build-up of hydraulic pressure beneath the cells when the tissue is unloaded.

Graphene is potentially attractive for electrochemical energy storage devices but whether it will lead to real technological progress is still unclear. Recent applications of graphene in battery technology and electrochemical capacitors are now assessed critically.

Three-dimensional analogues of graphene have recently been synthesized. The transport properties of such a Dirac semimetal, Cd₃As₂, have been studied, revealing an unexpected mechanism that suppresses backscattering dramatically.

Monolayer iron selenide grown on SrTiO₃ has recently gained attention due to suggestive evidence it superconducts at high temperature. In situ electrical transport measurements now reveal a transition temperature above 100 K.

The lifting of valley degeneracy in the monolayer transition metal dichalcogenide WS₂ is now demonstrated by the optical Stark effect, showing that each valley can be selectively tuned by up to 18 meV.

A high density of strong hydrogen bonds connecting two polymers that are homogeneously mixed in a thin film is shown to enhance the intrachain thermal conductance, boosting thermal transport in fully organic layers.

Monolayers of graphene, boron nitride and transition metal dichalcogenides are stacked in vertical heterostructures to realize light-emitting devices based on single and multiple quantum wells, with bright electroluminescence up to room temperature.

The usual model of glass corrosion is based on diffusion-coupled hydration and selective cation release. A novel corrosion mechanism now suggests that interfacial dissolution–reprecipitation may be a universal process that controls both silicate glass corrosion and mineral weathering.

Entropic elasticity, typical of rubbers and known to also occur in organic polymers with certain network structures, is now demonstrated for phosphate-glass fibres with highly anisotropic structures.

Symmetry-breaking distortion on the surface of topological crystalline insulators imparts mass to Dirac electrons. The mass is shown to depend on the penetration depth of the surface states. Non-topological surface states are also reported.

Enhancing the superconducting temperature is often the main driver of synthetic studies of novel superconducting materials. Now, an approach yielding an air-stable iron selenide system that superconducts up to 40 K is reported.

Molecular design rules are defined to obtain metal-free blue-emitting organic compounds that show thermally activated delayed fluorescence with high photoluminescence efficiency. An internal electroluminescence quantum efficiency of 100% is reached.

A generalized theory is provided for the quantitative description of wrinkling morphologies and of the transitions between surface patterns in curved elastic bilayer materials.

Measurements in stretched epithelial cell sheets show that epithelial cracks are independent of tension and that epithelial fracture is caused by the hydraulic pressure that builds up in the extracellular matrix during stretching.

Transdermal light-triggered activation of cell-adhesive peptides on the surface of implanted hydrogels alters cell–material interactions, such as cell adhesion and spatial patterning, and fibrous encapsulation and vascularization of the material.

This focus issue highlights a range of material systems used by the nuclear-power industry, such as those utilized in reactor cores and in the disposal of spent nuclear fuel, and discusses the importance of understanding radiation effects on these materials and related processes over a range of length and temporal scales.