Magnetic nanocomposites, annealed under stress, are investigated for application in inductive devices. Stress annealed Co-based metal/amorphous nanocomposites (MANCs) previously demonstrated induced magnetic anisotropies greater than an order of magnitude larger than field annealed Co-based MANCs and response to applied stress twice that of Fe-based MANCs. Transverse magnetic anisotropies and switching by rotational processes impact anomalous eddy current losses at high frequencies. Here we review induced anisotropies in soft magnetic materials and show new Co-based MANCs having seven times the response to stress annealing as compared to Fe-based MANC systems. This response correlates with the alloying of early transition metal elements (TE) that affect both induced anisotropies and resistivities. At optimal alloy compositions, these alloys exhibit a nearly linear B–H loop, with tunable permeabilities. The electrical resistivity is not a function of processing stress but trends in electrical resistivity and induced anisotropy with choice and concentration of TE content are clearly resolved. Previously reported and record-level induced anisotropies, K u, ∼20 kJ/m3 (anisotropy fields, H K ∼ 500 Oe), in stress annealed Co-rich MANCs are increased to K u ∼ 70 kJ/m3 (H K > 1800 Oe) in new systems.

The aim of this study was to obtain a tridimensional electrode with an even greater specific surface area (a s), using the electrodeposition of PbO2 films onto 45, 60, and 80 ppi RVC substrates applying different current densities. The kinetics and efficiency of decolorization of Reactive Blue 19 (RB19) dye achieved with the 60 ppi RVC/PbO2 were higher than obtained with a flat PbO2 electrode and 45 ppi RVC/PbO2, due not only to a greater electrochemically active area, but also especially due to the substantial increase in mass transfer caused by the turbulence generated by the porous matrix. It was found that the coating and the formation of β-PbO2 was only possible on the 60 ppi substrate applying 3.5 mA/cm2; in the case of the 80 ppi substrate, the uneven distribution of potential and current within the porous electrode did not allow establishment of suitable operational conditions that permitted complete and uniform coating of the substrate.

In this study, the effects of Ag variations on dynamic recrystallization (DRX), texture, and mechanical properties of ultrafine-grained Mg–3Al–1Zn alloys are investigated. The results suggest that Ag segregation and Al–Zn–Ag clusters form in the Mg matrix with Ag addition less than 1 wt%, which retard DRX and the growth of the DRXed grains. The resulting grain size decreases from 513 to 316 nm. As the Ag addition increases to 2 wt%, the Mg54Ag17 phase precipitates along the grain boundary, which plays an important role in restricting DRXed grain growth via grain boundary pinning effect. The resulting grain size is 375 nm with a bimodal grain size distribution. The extrusion texture of the investigated alloys is in fairly scattered orientation distribution. The weak basal texture and ultrafine grain size lead to the high yield asymmetry ratio. The Ag-containing extruded alloys exhibit an increase in the tensile and compressive properties. The strengthening mechanisms due to grain refinement, dislocations, solid solution, precipitates, solute clusters, and segregation are discussed.

Layered transition metal oxides are some of the most important materials for high energy and power density electrochemical energy storage, such as batteries and electrochemical capacitors. These oxides can efficiently store charge via intercalation of ions into the interlayer vacant sites of the bulk material. The interlayer can be tuned to modify the electrochemical environment of the intercalating species to allow improved interfacial charge transfer and/or solid-state diffusion. The ability to fine-tune the solid-state environment for energy storage is highly beneficial for the design of layered oxides for specific mechanisms, including multivalent ion intercalation. This review focuses on the benefits as well as the methods for interlayer modification of layered oxides, which include the presence of structural water, solvent cointercalation and exchange, cation exchange, polymers, and small molecules, exfoliation, and exfoliated heterostructures. These methods are an important design tool for further development of layered oxides for electrochemical energy storage applications.

The manner in which structure at the mesoscale affects emergent collective dynamics has become the focus of much attention owing, in part, to new insights into how morphology on these spatial scales can be exploited for enhancement and optimization of macroscopic properties. Key to advancements in this area is development of multimodal characterization tools, wherein access to a large parameter space (energy, space, and time) is achieved (ideally) with a single instrument. Here, we describe the study of optomechanical responses of single-crystal Si cantilevers with an ultrafast electron microscope. By conducting structural-dynamics studies in both real and reciprocal space, we are able to visualize MHz vibrational responses from atomic- to micrometer-scale dimensions. With nanosecond selected-area and convergent-beam diffraction, we demonstrate the effects of spatial signal averaging on the isolation and identification of eigenmodes of the cantilever. We find that the reciprocal-space methods reveal eigenmodes mainly below 5 MHz, indicative of the first five vibrational eigenvalues for the cantilever geometry studied here. With nanosecond real-space imaging, however, we are able to visualize local vibrational frequencies exceeding 30 MHz. The heterogeneously-distributed vibrational response is mapped via generation of pixel-by-pixel time-dependent Fourier spectra, which reveal the localized high-frequency modes, whose presence is not detected with parallel-beam diffraction. By correlating the transient response of the three modalities, the oscillation, and dissipation of the optomechanical response can be compared to a linear-elastic model to isolate and identify the spatial three-dimensional dynamics.