Atomic layer deposition (ALD) of air stable cobalt and nickel complexes based on tridentate enaminones N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethylethyldiamine (Htfb-dmeda) and N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethylpropyldiamine (Htfb-dmpda) successfully produced metallic cobalt and nickel thin films. Detailed X-ray photoelectron spectroscopy (XPS) studies on the binding interaction of the first precursor monolayer with the surface functional groups elucidated the chemisorption behavior of the new precursor systems. A reactive remote hydrogen plasma was used as the co-reactant to activate the precursor decomposition yielding metal hydroxide intermediates. Subsequent hydrogen plasma etching of as-deposited films resulted in phase-pure metallic films through a recrystallization process, verified by surface and sub-surface XPS. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed pinhole-free films, with low surface roughness (0.2 ± 0.06 nm root mean square, RMS) for both, cobalt and nickel thin films. Herein, the competitive role of hydrogen as etchant and reactant was demonstrated as prolonged plasma exposure time periods resulted in the formation of metal hydrides. This is mostly due to the catalytic dissociation of molecular hydrogen on transition metal surfaces, which already occurs upon low energy input.

The flow softening behavior caused by deformation heating of the 6063 aluminum alloy was investigated employing uniaxial compression tests. The adiabatic correction factor (η) and mechanical work partitioning factor (φ), commonly considered to be constant, were found to be highly variable at medium strain rates, namely from 0.01 to 10 s−1. η decreased with increasing strain and decreasing strain rate, but it was relatively not sensitive to temperature. φ, traditionally taken to be a constant of 0–10%, was found to vary from 2.8% at a temperature of 623 K and a strain rate of 10 s−1 to 26.8% at a temperature of 773 K with a strain rate of 0.01 s−1. An expression for temperature rise involving these two variable factors was optimized. FEM simulation using the corrected and uncorrected true stress–strain curves and corresponding extrusion experiment were carried out. Comparisons between the simulated and experimental results confirmed the temperature compensation was trustable.

A mechanical model is developed to explain the influence of grain rotation on nanovoid growth in nanocrystalline solids in the current paper. In the framework of the mechanical model, the dislocations released from the nanovoid surface will be affected by four stresses: the driving stress induced by far-field stress, the stress arising from grain rotation, the image stress caused by the free surface of the nanovoid, and the back stress generated by the previously emitted dislocations. Furthermore, under the condition of different rotational strength and surface effects, we analyzed in detail the influence of the important parameters such as nanovoid radius, nucleation radius, dislocation emission angle, relative distance, rotation grain size, rotation coefficient, and direction angle on the critical stress. Finally, we discuss the effect of the coupling of rotational deformation and the grain boundary on the growth of the nanovoid. As a conclusion, the high stress nearby the nanovoid can be released by grain rotation, which inhibits the growth of the nanovoid.

Strain-mediated magnetoelectric coupling provides a powerful method for controlling nanoscale magnetism with an electric voltage. This article reviews the initial use of macroscale composites and subsequent experimental control of magnetic thin films, nanoscale heterostructures, and single domains. The discussion highlights several characteristics enabling small, fast, and energy-efficient technologies. The second section covers applications where strain-mediated magnetoelectricity has been used, with emphasis on the storage, transmission, and processing of information (i.e., memory, antenna, and logic devices). These advances are order-of-magnitude improvements over conventional technologies, and open up exciting new possibilities.

There is currently a need for an efficient approach to control magnetism at small scales (<1 mm). Work on these magnetoelectric concepts dates back to the 19th century, when researchers believed that a material could convert electrical to magnetic energy, similar to Oersted’s discovery, made by passing a current through a wire. Today, there are significant magnetoelectric research opportunities in both materials discovery and theoretical modeling efforts to advance this important area of magnetic control. Applications for these strain-mediated magnetoelectric materials range from replacing existing inefficient magnetic memory approaches to spearheading new discoveries, such as micrometer-size electromagnetic motors enabling robotic manipulation. This article and the other articles in this issue provide the motivation, background information, research opportunities, and novel applications for studying strain-mediated magnetoelectric materials. The issue is designed to encourage additional research on magnetoelectrics due to its potential impact on society through the efficient control of magnetism at the micro- and nanoscale.

Recently, double perovskite-based oxide materials have been proposed for thermoelectric (TE) applications due to their environment-friendly nature, high-temperature stability, better oxidation resistance, and lower processing cost compared to conventional chalcogenides and intermetallics. In this review article, we have comprehensively summarized our recent research studies on Sr2B′B″O6-based double perovskites for high-temperature TE power generation. We have shown that decoupling of phonon-glass and electron-crystal behavior is possible in oxides by reducing thermal conductivity due to induced dipolar glassy state as a result of relaxor ferroelectricity. We have also introduced metal-like electrical conductivity (∼105 S/m) in these ceramics that are inherently insulator in nature. Moreover, we have observed interesting behavior of temperature-driven p–n type conduction switching assisted colossal change in thermopower in some of these oxides, hitherto, obtained only in chalcogenides. The charge transport mechanism in these complex oxides has been analyzed by small polaron hopping conduction model in conjugation with defect chemistry.