The authors summarize the results of selective-area growth of vertical MnAs/InAs heterojunction nanowire (NW) arrays and present a preliminary characterization of the transport properties of a single MnAs/InAs heterojunction NW and a single InAs host NW for MnAs inclusions. During the endotaxy of MnAs after the selective-area growth of host InAs nanowires (NWs) on partially SiO2-masked GaAs(111)B substrates, hexagonal NiAs-type MnAs nanoclusters (NCs), which exhibit spontaneous magnetization at room temperature, are formed with the 〈0001〉 direction oriented parallel to the 〈111〉B direction of the zinc-blende-type InAs host NWs. For InAs host NWs, a large positive ordinary magnetoresistance (MR) effect up to 165% is observed at temperatures between 7 and 280 K. In addition, magnetotransport measurements reveal universal conductance fluctuations and a weak Anderson localization at temperatures up to 20 K due to a charge-accumulation layer formed at the surface. Single MnAs/InAs heterojunction NWs, however, exhibit only a negative MR effect, which is independent of temperature T < 10 K and linearly decreases up to −10% at 10 T with increasing magnetic field. These results reveal the tremendous influence of ferromagnetic NCs on the transport behavior inside the InAs host NWs.

Multifunctional nanoparticles are an emerging area of research, impacting numerous fields ranging from biomedical applications to energy. While initial core–shell structures consisted of similar materials, such as Au–Ag or CdTe–CdSe nanoparticles, recent work has expanded this line of investigation to include particles of dissimilar materials. However, there are several challenges when synthesizing dissimilar material systems. In this work, a method for doping the shell of an Au–ZnO nanosphere is demonstrated. Several metal dopants are investigated, including Cu, Ce, Er, Nd, Tm, and Yb. The ZnO shell is nucleated on the gold nanosphere core via an ascorbic acid–assisted growth, and the dopant is intercalated uniformly into the shell during the self-assembly phase of the shell formation. The doping and polycrystalline shell are confirmed using a series of qualitative and quantitative methods. This multi-material nanoparticle synthesis strategy opens the door for future applications in sensing, photocatalysis, and bioimaging.

Mechanical fracture of electrodes will occur during lithiation caused by large volume changes, which leads to the capacity loss of the lithium-ion battery. Herein, we present a new analytical model to investigate the effect of creep deformation on stress relaxation and fracture of the lithiated tin (Sn) electrode under the galvanostatic and potentiostatic operation. Interestingly, it is found that the presence of creep can improve fracture resistance and toughness of the Sn electrode. In addition, the surface effect has the capacity to weaken the creep deformation effectively. And the different size of the Sn electrode shows different effects for creep deformation. This conclusion explains the difference in charging conditions, and the mechanism of stress change inside the electrode is also different. Deeply, the base on our model, the stress strength factor, and critical size of the electrode have been evaluated under galvanostatic and potentiostatic operation with creep deformation effects. Finally, the safety area during lithiation is established to determine the critical size of the Sn electrode. And the presence of creep deformation may significantly increase critical dimensions of the electrode. These results will provide a valuable basis to design the durable electrodes.

Chitosan has attracted significant attention in the past decade because of its potential applications in water engineering, the food and nutrition technology, the textile and paper industries, and drug delivery. Recently, a particularly interesting application of chitosan has been proposed in transparent flexible electronic devices, including memristors and transistors. In this work, the resistive switching (RS) effect of chitosan thin films in a capacitor-like structure with Ag and Al as alternative top electrodes was studied. Both the devices showed a bistable RS effect under an external electric field with a high endurance of 102. The electrical conduction and RS mechanisms of chitosan-based devices were investigated. The trap-controlled space charge–limited current was responsible for electrical transport at the low-resistance state of both devices, while direct tunneling and Schottky emission at the high-resistance state were related to Ag/chitosan/fluorine-doped tin oxide (FTO) and Al/chitosan/FTO, respectively. The RS mechanism of the Ag/chitosan/FTO device was attributed to the formation and dissociation of Ag filaments through the dielectric layer, whereas the change in the barrier height at the Al and chitosan interface under an external electric field could control the RS mechanism of the Al/chitosan/FTO device.

Rational construction of Z-scheme photocatalysts and exploration of the Z-scheme charge transfer mechanism have drawn much attention in the field of CO2 reduction because of its great potential to alleviate energy crisis and environmental problems. In this study, a series of Z-scheme CdS/BiOI composites were constructed by depositing CdS nanoparticles on the surface of BiOI nanosheets. The synthesized materials were characterized comprehensively, and their photoreduction CO2 activities were evaluated. The results show that the composites exhibit higher photoreduction CO2 activity under visible light irradiation (λ > 400 nm) than pure CdS and BiOI. The yields of CO and CH4 for the optimal composite after 3 h irradiation are 3.32 and 0.54 μmol/g, respectively. The improved photocatalytic activity is attributed to Z-scheme transfer mode of the photogenerated charges in the composites. The mechanism of CO2 reduction is proposed and verified experimentally.

There is no agreement regarding which solvent is more suitable to obtain sol–gel–derived titania (TiO2) samples with an enhanced photocatalytic behavior. Furthermore, the solvent effect on the preparation of TiO2-RGO (reduced graphene oxide) nanocomposites has not been published yet and could be an attractive experimental strategy to modulate structure and properties. On the basis of these observations, TiO2-RGO nanocomposites were fabricated in this study. It was evaluated for the influence of using either isopropyl (IsoprOH) or ethyl (EtOH) alcohol on the textural and photocatalytic properties of the prepared materials. The use of IsoprOH led to samples with smaller crystallite size, narrower apparent band gap, smaller isoelectric point, larger adsorption capacity, and higher photocatalytic activity. In addition, the incorporation of RGO into TiO2 greatly improved the adsorption capacity and photocatalytic activity of the latter. However, the optimal loading of RGO to prepare composites with enhanced photocatalytic activities was 1 wt%. This finding can be related to the stacking of RGO sheets when concentrations above 1 wt% are used, which could prevent UV light to reach the TiO2 particles and also decrease the photocatalytic capacity of the composites. Moreover, materials with RGO concentration above 1 wt% could exhibit a highly negatively charged surface, which may decrease the separation of the generated electron–hole pairs and lead to faster recombination rates of charge carriers.

Solar-grade multicrystalline silicon ingots as raw material for solar cells were obtained from upgraded metallurgical silicon by directional solidification in an axial magnetic field. The influence of preparation technology on the microstructural characteristics of silicon ingots was investigated. Governing equations were used to simulate the silicon fluid flow and thermal fields during directional solidification. The results show that appropriately increasing melt temperature and/or decreasing pulling-down rate can be conductive to the growth of a coarse columnar grain. Meanwhile, the axial magnetic field promotes the formation of low-energy ∑3 twin boundaries and reduces the dislocations and impurities, where the total concentration of major metal impurities is with a mean of 0.459 ppmw in the range of 1/9 to 8/9 of height along the growth direction. It is shown from the simulation results that suppressing silicon melt flow in both radial and azimuthal directions and reducing the growth rate in the edge regions contribute to the formation of a flat solid–liquid interface, which is more consistent with the experimental results. Moreover, the formation mechanism of the twins and removal mechanism of the impurities were discussed.

In this article, the strain-dependent thermoelectric performance of circular porous armchair silicene nanoribbons (ASiNRs) under uniaxial tension and compression is computed by means of a semiempirical approach in combination with nonequilibrium Green’s function. Our findings clearly demonstrate that the thermoelectric performance can be effectively tuned by the optimum choice of the nature and magnitude of the strain depending on the pore size. For smaller pore sizes, higher tensile strains can be preferred whereas for nanostructures with larger pores, the compression is a suitable option. Further analysis concludes that the tensile deformation fails to attain any improvement in the thermoelectric figure of merit ZT at any choice of temperature, whereas the performance under compressive deformation goes on improving with the increase in the applied temperature. In addition, changing the pore shape to a triangular one is found to significantly enhance the thermoelectric performance.

Measuring the elastic and plastic properties with nanoindentation is predicated on the indentation not fracturing the material. In this study, an unloading curve analysis is used to identify indentation-induced fracture in brittle molecular organic crystals to define conditions, where properties measurements are accurate, and for calculating the toughness. Single crystals of cyclotetramethylene tetranitramine (HMX) and idoxuridine were indented from 1 to 300 mN with indenter probes of varying acuity to identify fracture initiation loads. Idoxuridine displayed no fracture up to and at 100 mN, with fracture occurrence then seen at an increasing rate until every indentation made induced fracture at 300 mN. HMX displayed no fracture up to and at 4 mN, with fracture then occurring at an increasing rate until every sample fractured at 8 mN. The toughness of HMX and idoxuridine is ≈0.28 ≈ 0.4–0.5 MPa/m1/2, respectively.

The global market requirement of ultra-fine iron powder (UFIP), with a range size of 0.1–1 μm, is more than 20,000 tons per annum. However, no low-cost nontoxic synthesis route of UFIP is known. In this study, we used the low-cost, rapid, and scalable flame aerosol synthesis (FAS) method to synthesize iron oxide nanoparticles with different size and morphology. Combining with a postreduction heat treatment process, a feasible synthesis route of UFIP which meets the commercial production criteria has been developed. By optimizing the precursor concentration and postreduction heat treatment parameters, the final particle size of UFIP can be controlled. The evolution of the microstructure, phase formation, and magnetic properties during the postreduction heat treatment are systematically investigated, and a feasible reaction model has been established. This work provides an important starting point for the facile commercial synthesis of UFIP and can be readily expanded to other pure metals.