The high cost of single-crystal III–V substrates limits the use of gallium arsenide (GaAs) and related sphalerite III–V materials in many applications, especially photovoltaics. However, by making devices from epitaxially grown III–V layers that are separated from a growth substrate, one can recycle the growth substrate to reduce costs. Here, we show damage-free removal of an epitaxial single-crystal GaAs film from its GaAs growth substrate using a laser that is absorbed by a smaller band gap, pseudomorphic indium gallium arsenide nitride layer grown between the substrate and the GaAs film. The liftoff process transfers the GaAs film to a flexible polymer substrate, and the transferred GaAs layer is indistinguishable in structural quality from its growth substrate.

Hybrid inorganic–organic perovskites have emerged over the last 5 years as a promising class of materials for optoelectronic applications. Most notably, their solar cells have achieved power conversion efficiencies above 20% in an unprecedented timeframe; however, many fundamental questions still remain about these materials. This Prospective Article reviews the procedures used to deposit hybrid perovskites and describes the resulting crystallographic and morphological structures. It further details the electrical and optical properties of perovskites and then concludes by highlighting a number of potential applications and the materials challenges that must be overcome before they can be realized.

Improvement of both solution and vapor-phase synthetic techniques for nanoscale ferroelectrics has fueled progress in fundamental understanding of the polar phase at reduced dimensions, and this physical insight has pushed the boundaries of ferroelectric phase stability and polarization switching to sub-10 nm dimensions. The development and characterization of new ferroelectric nanomaterials has opened new avenues toward future nonvolatile memories, devices for energy storage and conversion, biosensors, and many other applications. This prospective will highlight recent progress on the synthesis, fundamental understanding, and applications of zero- and one-dimensional ferroelectric nanomaterials and propose new directions for future study in all three areas.

Solution-processed hole contact layers (HCLs) of metal oxide nanoparticle (NP) films improve performance of organic photovoltaics (OPVs), but have thus far required harsh post-deposition thermal or plasma treatments. Here, we describe a general method to synthesize suspensions of ultrasmall (1–2 nm) MoO3, WO3, NiOx, and CoOx NPs in n-butanol. Spin-coated metal oxide NP films with no post-deposition treatment exhibit high work function and ionization energy consistent with the oxidation states of the metal cations. Metal oxide NP HCLs demonstrate performance matching those of reference conventional and inverted OPVs containing PEDOT:PSS and evaporated MoO3.

Described is a simple one-pot route for the synthesis of hierarchically porous carbon supported palladium (Pd/C) monoliths with a three-dimensional pore network via self-assembly under basic conditions of a resol polymer. Textural and morphological characterization of the Pd/C monoliths was carried out using nitrogen sorption analysis and scanning electron microscope. Formation of Pd nanoparticles ranging from 35 to 60 nm was observed. Evaluation of catalytic activity for styrene hydrogenation was performed using the Pd/C material as heterogeneous catalyst in batch mode. Studies revealed that the monoliths showed leaching and catalytic activity similar to a commercial Pd/C catalyst.

What musical notes can a molecule play? Carbyne is a chain of atoms that vibrates similar to an elastic string. Like the tuning of a guitar string, this vibration can be predicted based on length and tension. Using atomistic simulation, we determine the vibrational response of carbyne. We further produce audible notes, enabling specific musical composition with prescribed molecular conditions (pre-strain and length) and combine single chains into multi-chain systems to form molecular chords. Since the tension of a molecular chain is relatively low (<nN), such “strings” can potentially be developed for signaling and detection with high resolution.

An ecofriendly synthesis is established to obtain ultra-small SnO2 nanoparticles (NPs) doped with metals by a hydrothermal method using only tin tetrachloride, urea, and water as reagents. This synthesis was done in a short period time at low temperature and without surfactants. Microscopy analysis revealed the formation of doped tin oxide NPs with a diameter smaller than 2.8 nm. Un-doped and doped tin oxides were obtained with a tetragonal type rutile structure with an average surface area of 348 m2/g.

Fullerite derivatives synthesized with a catalytic polymerization reaction at a relatively low-pressure range of 0.5–4 GPa show unique mechanical properties: elastic recovery is 98% and hardness possibly approaches 100 GPa. Structure of the samples is also unique: one composes from fragments of C60 molecules linked by the covalent bonds. To obtain the homogeneous crack-free samples, we synthesized B4C–fullerite derivatives composite which show a 550 MPa flexural stress, a 2250 MPa compressive strength, and a 28 GPa hardness and have density of 2.2 g/cm3.

In this study, Vickers indentation was used to investigate the two-way shape-memory effect (TWSME) in an austenitic Ti-50.9 at.% Ni alloy, exposed to different heat treatments. Three aging treatments were used to manipulate the size of Ti3Ni4 precipitates. All samples were Vickers indented, and the indent depth was investigated as function of thermal cycling. The TWSME was found only in the material aged at 400 °C, which contained coherent precipitates. Thermal cycling shows stable TWSME, however, heating well above the austenite finish temperature lead to permanent austenitic protrusions. The results indicate that stabilized martensite plays a critical role in creating TWSME surfaces.

Regarding the significance of cement paste in construction materials, the present paper aims to use nanoindentation to measure and map mechanical properties of hardened cement pastes. The mechanical properties of involved phases were extracted from grid nanoindentation on the cement paste. The results suggested that nanoindentation can be used as a tool to measure and map mechanical properties of hardened cement pastes, and can identify the phases, including outer product, inner product, calcium hydroxide (or interface of residual cement clinker), and residual cement clinker.

This paper aims to obtain an analytical expression for the ratio of unloading work of indentation (Wu) to total loading work of indentation (Wt) (work recovery ratio of indentation) in instrumented spherical indentation. The expanding cavity model and Lamé solution are used. Three typical stress–strain relations (elastic-perfectly plastic, linear hardening, and power-law hardening) are analyzed. The results of finite-element method coincide with the expressions. The expressions show that the work recovery ratio of indentation is just related to plastic parameters. Furthermore, elastic work (We) are obtained, and it is proved that We should be distinguished from Wu in spherical indentation.