Research articles

Uranium dioxide is commonly doped with chromium to improve its performance as a nuclear fuel. Here, with the aid of ab initio simulations and re-evaluation of experimental data, the oxidation state of chromium in the uranium dioxide lattice is identified as +2, not the widely believed +3.

Brick-and-mortar composite structures found in nature are known for their superior mechanical performance. Here, computational approaches are used to understand the key design features that control mechanical behavior, providing guidance for the design of improved composites.

Cu₂O is of great interest for its excitonic properties, yet challenges in its fabrication means that most experiments focus on naturally occurring samples. Here, scalable thermal oxidation is reported for the growth of Cu₂O with low-defect content, allowing the observation of Rydberg excitons.

Spider silk is well known for its high toughness. Here, a comprehensive study of the simultaneous effect of strain rate and humidity on toughness is reported, revealing that toughness is highest under mildly humid conditions and at high strain rates, similar conditions to those in nature.

Nano-scale coatings are important for controlling the functional behavior of surfaces. Here, a deposition process in liquid hydrocarbons is reported for metal oxides, in which a thin water coating on the substrate reacts with chemical precursors, forming a nano-scale layer.

The intrinsic flexibility of molecules opens the door to unusual physical properties. Now, a large thermal expansion coefficient of 980 ± 110 × 10⁻⁶ K⁻¹ is observed by scanning probe microscopy in a supramolecular network on a gold surface.

Controlling spatial conductivity in graphene is important for plasmonic devices, yet conductivity patterning typically changes the electromagnetic environment. Here, teraherz plasmons in graphene are confined to specific regions via a patterned zinc oxide gate, reducing electromagnetic coupling.

Mid-infrared optical modulators are important for detecting compounds in a wide range of applications, but are typically limited to short wavelengths. Now, a SiGe waveguide is used to fabricate an optical modulator that can reach wavelengths spanning 5.5 µm to 11 µm.

High-throughput prediction and synthesis are vital for obtaining new materials that deviate from existing compositions. Here, machine learning is combined with high-throughput synthesis to identify superionic conductors based on Ca-(Nb,Ta)-Bi-O.

Ferroelastic materials undergo first-order structural transitions. Here, acoustic and strain measurements are simultaneously combined during a reversible martensitic transformation in a shape memory alloy, allowing the key microstructure processes to be tracked.

Polar metal oxides are not frequently observed, yet offer attractive properties for functional devices. Now, high-throughput structure screening of a thousand crystal structures reveals that BiPbTi₂O₆ can form both polar and metallic structures.

Ring polymers are known to display a variety of unusual dynamical behavior due to their topology. Here, simulations reveal that ring polymers under shear flow exhibit a swelling of the ring, causing them to behave as non-Brownian particles.