Volume 20 Issue 3, March 2021

Electron microscopy touches on nearly every aspect of modern life, underpinning materials development for quantum computing, energy and medicine. We discuss the open, highly integrated and data-driven microscopy architecture needed to realize transformative discoveries in the coming decade.

Sir John Meurig Thomas, who was one of the leading materials and catalytic scientists of his generation, sadly died in November 2020, aged 87.

Stress fibres form a fully integrated meshwork with the submembranous contractile actin cortex that generates and propagates traction forces across the entire cell.

A light-induced topological phase transition is realized in the Dirac semimetal ZrTe₅ by coherently driving symmetry-breaking phonons.

An elaborate DNA origami tubular nanodevice encapsulating antigens and adjuvants protects mice from cancer through tumour-specific immunomodulation.

Nanoporous tripeptide crystals mechanically deform upon water evaporation due to the strengthening of the water hydrogen bonding inside the pores, which causes the distortion of the surrounding supramolecular network, creating stresses that extend through the crystal lattice and result in actuation.

Non-fullerene acceptors have successfully overcome energy losses that were thought to be unavoidable in organic solar cells based on fullerene derivatives. However, it is now shown that they have limits too.

Using group theory and first principles calculations, it is shown that an analogue of the Dzyaloshinskii–Moriya interaction that allows the antisymmetric exchange spin coupling in magnets exists in ferroelectrics.

This Perspective provides a broad introduction to topological materials science, with a particular focus on semimetals.

Triple ionic–electronic conductors can be used in electrochemical devices, including fuel cells, membrane reactors and electrolysis cells. Current understanding in single-phase conductors including defect formation and conduction mechanisms are now discussed.

In contrast with conventional views, ultra-large-scale atomistic simulations show that the staged character of strain hardening of metals originates from crystal rotation, whereas the dislocation behaviours remain the same across all the stages.

Comparison of hexagonal boron nitride samples grown with different techniques and with varying carbon-doping content provides evidence that the defects emitting single photons in the visible range are carbon related.

Femtosecond optical pulses are used to generate coherent phonons that break inversion symmetry and drive anisotropic terahertz photocurrents in the topological material ZrTe₅.

Antiskyrmions had only been observed in a few Heusler compounds with D_2d symmetry. Here a new material, Fe_1.9Ni_0.9Pd_0.2P, in a different symmetry class (S₄ symmetry) is reported to host antiskyrmions, as well as sawtooth surface textures and skyrmions.

The Dzyaloshinskii–Moriya interaction (DMI) enables coupling of magnetic spins and is responsible for non-collinear phenomena such as skyrmions. Here, using first-principles simulations and group theory analysis, it is demonstrated that an electric DMI exists and is analogous to the magnetic DMI.

Metallic nanoparticles used to harvest energy from a light source typically result in reduced chemical reaction temperature. Endothermic reactions requiring higher activation energy can now be initiated at room temperature using localized surface plasmons in the deep-UV range.

Sodium ion batteries could be an attractive alternative to Li-ion technology but designing high energy density and moisture stable Na-based cathodes is challenging. Adjusting synthesis conditions and stoichiometry, an O3-type NaLi_1/3Mn_2/3O₂ phase with anionic redox activity is reported.

Zeolite membranes can be used for gas molecular sieving, but synthesis requires complex hydrothermal treatment. Here, single layers of zeolite precursor RUB-15 are exfoliated followed by a condensation reaction, forming zeolite membranes with H₂/CO₂ selectivity of 20 to 100 in a facile process.

Phosphonated polymers have been proposed as anhydrous proton conductors for fuel cells but anhydride formation of phosphonic acid functional groups lowers conductivity. A synergistically integrated phosphonated poly(pentafluorostyrene) is shown to maintain high protonic conductivity above 200 °C.

A systematic analysis of a series of donor–acceptor organic blends shows that in solar cells based on low-bandgap non-fullerene acceptors an ionization energy offset of about 0.5 eV is required to ensure efficient charge separation.

Periodic patterns with varying cross-linking densities are realized in conjugated polydiacetylene films, creating multiple holographic images—all dynamically responsive to exposure to various solvents—simultaneously in the same polymeric structures.

Self-assembling, histidine-rich peptides with similar catalytic functions as those of haem-dependent peroxidases are reported. These findings may have implications for the design of cofactor-free catalytic nanomaterials.

Experiments and molecular dynamics simulations show that the dehydration-induced actuation of nanoporous tripeptide crystals is a result of pore contraction caused by the strengthening of the water hydrogen-bonding network inside the pore, which creates mechanical stress that deforms the crystal lattice.

The mechanism of stress fibre assembly by the coalescence of actin filaments in the cell cortex has now been found to account for the transmission of mechanical forces throughout the entire cell along stress fibres.

A DNA nanodevice vaccine has been developed and utilized to stimulate a tumour-specific cytotoxic T lymphocyte response in vivo, leading to the inhibition of tumour growth as well as prevention of metastasis.