A mnemonic scheme is presented to help recall the equations in classical thermodynamics that connect the four state variables (temperature, pressure, volume, and entropy) to the four thermodynamic potentials (internal energy, Helmholtz free energy, enthalpy, and Gibbs free energy). Max Born created a square to help recall the thermodynamic equations. The new scheme here separates the Max Born square into two squares, resulting in easier recalling of several sets of equations, including the Maxwell equations, without complicated rules to remember the positive or negative signs.

Advanced nuclear energy systems, both fission- and fusion-based, aim to operate at higher temperatures and greater radiation exposure levels than experienced in current light water reactors. Additionally, they are envisioned to operate in coolants such as helium and sodium that allow for higher operating temperatures. Because of these unique environments, different requirements and challenges are presented for both structural materials and fuel cladding. For core and cladding applications in intermediate-temperature reactors (400–650°C), the primary candidates are 9–12Cr ferritic–martensitic steels (where the numbers represent the weight percentage of Cr in the material, i.e., 9–12 wt%) and advanced austenitic steels, adapted to maximize high-temperature strength without compromising lower temperature toughness. For very high temperature reactors (>650°C), strength and oxidation resistance are more critical. In such conditions, high-temperature metals as well as ceramics and ceramic composites are candidates. For all advanced systems operating at high pressures, performance of the pressure boundary materials (i.e., those components responsible for containing the high-pressure liquids or gases that cool the reactor) is critical to reactor safety. For some reactors, pressure vessels are anticipated to be significantly larger and thicker than those used in light water reactors. The properties through the entire thickness of these components, including the effects of radiation damage as a function of damage rate, are important. For all of these advanced systems, optimizing the microstructures of candidate materials will allow for improved radiation and high-temperature performance in nuclear applications, and advanced modeling tools provide a basis for developing optimized microstructures.

With the ability to locate and identify atoms in three dimensions, atom-probe tomography (APT) has revolutionized our understanding of structure-property relationships in materials used for structural applications. The atomic-scale details of clusters, second phases, and microstructural defects that control alloy properties have been investigated, providing an unprecedented level of detail on the origins of aging behavior, strength, creep, fracture toughness, corrosion, and irradiation resistance. Moreover, atomic-scale microscopy combined with atomistic simulation and theoretical modeling of material behavior can guide new alloy design. In this article, selected examples highlight how APT has led to a deeper understanding of materials structures and therefore properties, starting with the phase transformations controlling the aging and strengthening behavior of complex Al-, Fe-, and Ni-based alloys systems. The chemistry of interfaces and structural defects that play a crucial role in high-temperature strengthening, fracture, and corrosion resistance are also discussed, with particular reference to Zr- and Al-alloys and FeAl intermetallics.

The physical phenomena and engineering applications of martensitic phase transformations are the focus of intense ongoing research. The martensitic phase transformation and functional properties such as the shape-memory effect and superelasticity are strongly affected by the crystal size at the nanoscale. The current state of research on the impact of crystal size on the phase stability of the martensite is reviewed summarizing experimental results of various nanostructured martensitic materials and discussing the corresponding theoretical approaches. The review outlines the effects of crystal size on the complex morphology of the martensite, leading to interface structures not encountered in coarse-grained bulk materials. The unique shape-memory properties of martensitic materials can persist even at the nanoscale. Nanocrystalline martensitic materials can be processed to obtain tailored functional properties in combination with enhanced strength. Structural changes of metallic nanowires are similar to those arising by martensitic phase transformations and also can lead to shape-memory effects, as predicted by atomistic simulations.

The stress required to deform a perfect crystal to its elastic limit while maintaining perfect periodicity, the so-called ideal strength, sets the gold standard for the strength of a given material. Materials this strong would be of obvious engineering importance, potentially enabling more efficient turbines for energy production, lighter materials for transportation applications, and more reliable materials for nuclear reactor applications. In practice, the strength of engineering materials is often more than two orders of magnitude less than the ideal strength due to easily activated deformation processes involving dislocations. For many materials, precipitate strengthening is a promising approach to impede dislocation motion and thereby improves strength and creep resistance. This observation begs the question: What are the limits of nanoparticle strengthening? Can the ideal strength of a matrix material be reached? To answer these questions, we need a detailed, atomic scale understanding of the interactions between dislocations and obstacles. Fortunately, simulations are beginning to explore this interaction.

Interface engineering and the study of diffusion and transport processes through and along interfacial regions play important roles in materials science and energy research. For the latter, nanostructured materials are increasingly considered to act as powerful electrodes and solid electrolytes in sustainable energy systems, such as Li ion batteries. This is due to reduced diffusion lengths achieved when going to the nanometer scale and the fact that nanocrystalline materials with an average particle size of less than about 50 nm often show an enhanced diffusivity of their charge carriers. In this article, we show examples of how solid-state nuclear magnetic resonance (NMR) spectroscopy can be used to study the diffusion parameters of Li cations located in the interfacial regions separately from those in the interior of the grains. This article will demonstrate the future challenges and perspectives of Li NMR as a powerful tool of probing dynamic properties in functional materials.

This article reviews the development of nonpolar and semipolar InGaN/GaN light-emitting diodes (LEDs), emphasizing structures on freestanding bulk GaN. A brief history of LED development on each orientation is provided, followed by a discussion of the most relevant and recent results. The context is related to several current LED issues, such as the realization of high-efficiency white solid-state lighting, potential solutions to the “green gap,” and applications for polarized emitters. The section on nonpolar LEDs highlights high-power violet and blue emitters and considers the effects of indium incorporation and substrate miscut. The section on semipolar GaN reviews the development of LEDs in the violet, blue, green, and yellow regions and highlights the potential of InGaN/GaN LEDs as an alternative technology to AlInGaP for yellow emitters. A brief review of polarization anisotropy also is included for each orientation. Finally, a two source white light system utilizing a nonpolar blue LED and a semipolar yellow LED is presented.

When light is absorbed in organic semiconductors, bound electron–hole pairs known as excitons are generated. The electrons and holes separate from each other at an interface between two semiconductors by electron transfer. It is advantageous to form well-ordered nanostructures so that all of the excitons can reach the interface between the two semiconductors and all of the charge carriers have a pathway to the appropriate electrode. This article discusses charge and exciton transport in organic semiconductors, as well as the opportunities for making highly efficient solar cells and for using carbon nanotubes to replace metal oxide electrodes.

The age of nuclear power originated with the gas-cooled, graphite-moderated reactor in the 1940s. Although this reactor design had intrinsic safety features and enjoyed initial widespread use, gas-cooled reactor technology was supplanted by higher power density water-cooled systems in the 1960s. However, the next-generation reactors seek enhanced power conversion efficiency and the ability to produce hydrogen, best accomplished with high-temperature gas-cooled systems. Thus, international interest in gas-cooled reactor systems is reemerging. Although the materials systems of these reactors are fairly simple, the reactor environment, particularly its high temperatures and intense irradiation, present extreme challenges in terms of material selection and survivability. This article provides a brief review of materials issues and recent progress related to graphite and ceramic materials for application in gas-cooled nuclear reactor environments. Of particular interest are the drastic, irradiation-induced microstructural evolution and thermophysical property changes occurring as a result of energetic neutron irradiation, which significantly impact the performance and lifetime of much of the reactor core. For “nuclear” graphite, the performance and lifetime not only are closely related to the irradiation environment but also are dramatically affected by the specifics of the particular graphite: manufacturing process, graphitization temperature, composition (amount of coke, filler, etc., depending on where it was mined), and so on. Moreover, the extreme environmental challenges set down by this next generation of fission nuclear plants have driven the development and application of ceramic composites for critical components, pushing beyond upper temperature limits set by metallic alloys used in previous generations of nuclear reactors. The composite material systems of particular interest are continuous carbon-fiber composites and newly developed radiation-resistant silicon carbide fiber composites.

Piezoresponse force microscopy (PFM) is a powerful method widely used for nanoscale studies of the electromechanical coupling effect in various materials systems. Here, we review recent progress in this field that demonstrates great potential of PFM for the investigation of static and dynamic properties of ferroelectric domains, nanofabrication and lithography, local functional control, and structural imaging in a variety of inorganic and organic materials, including piezoelectrics, semiconductors, polymers, biomolecules, and biological systems. Future pathways for PFM application in high-density data storage, nanofabrication, and spectroscopy are discussed.

The need for high-κ gate dielectrics and metal gates in advanced integrated circuits has reopened the door to Ge and III–V compounds as potential replacements for silicon channels, offering the possibility to further increase the performances of complementary metal oxide semiconductor (CMOS) circuits, as well as adding new functionalities. Yet, a fundamental issue related to high-mobility channels in CMOS circuits is the electrical passivation of their interfaces (i.e., achieving a low density of interface defects) approaching state-of-the-art Si-based devices. Here we discuss promising approaches for the passivation of Ge and III–V compounds and highlight insights obtained by combining experimental characterization techniques with first-principles simulations.

The present and future demands of industrial bulk crystal growth from the melt are concentrated on improved crystal quality, increased yield, and reduced costs. To meet these challenges, the size of the melt volume must be markedly increased. As a result, violent convective perturbations appear within the melts due to turbulent heat and mass flows. They disturb the single crystal growth and give rise to compositional inhomogeneities. The application of external force fields is an effective method to dampen and control these flows. After introducing different stabilizing variants, such as constant and accelerated melt rotation, mechanical vibrations, and electric current, this article focuses on the use of magnetic fields. Nonsteady fields became very popular because, in this case, the needed strength of the magnetic induction is much lower than for steady fields. A new low-energy low-cost technology that combines heat and magnetic field generation in one module placed close to the melt crucible is introduced.

Polymers have been extensively utilized in the design of nanometer-sized delivery vehicles of chemotherapeutics for clinical cancer therapy. Polymeric nanoparticulate delivery vehicles, with chemotherapeutics being either conjugated or encapsulated, have been developed into a variety of different architectures, including polymer-drug conjugates with linear or branched polymers, micelles, and polymersomes. This review describes the progress that has been made in the field of polymeric nanomedicine that brings the science closer to clinical realization of nanopolymeric therapeutics for its application in cancer treatment.

This article reviews investigations of the growth and reactions within thin metal and oxide films using atom-probe tomography. Included in this review are (1) studies of interfacial and growth reactions in magnetoresistive metallic, metal/oxide, and magnetic magnetostrictive multilayers; (2) comparison of selected portions of these results to simulated film growth using molecular dynamics; and (3) study of the origin of room-temperature ferromagnetism in dilute magnetic semiconductors. Information of this type is useful in order to understand the formation and thermal evolution of thin films (and to compare to theory and modeling) and, ultimately, to permit further optimization of devices based on thin films.

The physical properties that make “functional” materials worthy of their moniker frequently arise because of a phase transition that establishes a new kind of order as the material is cooled from a parent state. Such ordered states include ferroelectrics, ferromagnets, and structurally ordered martensites; because these states all break an orientational symmetry, and it is rare that one can produce the conditions for single domain crystallinity, the observed configuration is generally heterogeneous. However, the conditions under which domain structures form are highly constrained, especially by elastic interactions within a solid; consequently, the observed structures are far from fully random, even if disorder is present. Often the structure of the heterogeneity is important to the function, as in shape-memory alloys. Increasingly, we are surprised to discover new phases inside solids that are themselves a heterogeneous modulation of their parents.

Nanoporous metals prepared by the corrosion of an alloy can take the form of monolithic, millimeter-sized bodies containing approximately 1015 nanoscale ligaments per cubic millimeter. The ligament size can reach down to the very limits of stability of nanoscale objects. The processes by which nanoporous metals are formed have continued to be fascinating, even though their study in relation to surface treatment, metal refinement, and failure mechanisms can be traced back to ancient times. In fact, the prospect of using alloy corrosion as a means of making nanomaterials for fundamental studies and functional applications has led to a revived interest in the process. The quite distinct mechanical properties of nanoporous metals are one of the focus points of this interest, as relevant studies probe the deformation behavior of crystals at the lower end of the size scale. Furthermore, the coupling of bulk stress and strain to the forces acting along the surface of nanoporous metals provide unique opportunities for controlling the mechanical behavior through external variables such as the electrical or chemical potentials.

Advanced fission-based reactors challenge our ability to fully understand environment–materials reactions in terms of fundamental stability and kinetics, including the influences of composition, microstructure, and system design, and to predict associated long-term performance. This article briefly describes corrosion reactions and the processes by which such are managed for several elevated-temperature environments associated with advanced reactor concepts: helium, molten Pb–Bi, fluorides, and supercritical water. For most of the subject environments, corrosion resistance critically depends on the ability to form and maintain protective surface layers. Effects of corrosion on mechanical behavior can be from thermally and chemically induced changes in microstructures or from environmental effects on cracking susceptibility. In most cases, the simultaneous effects of chemical reactivity and radiation have not been fully addressed, nor has much attention been paid to newly emerging alloy compositions or the effects of substantially increased operating temperatures.

To achieve 520–532 nm green laser diodes (LDs), nonpolar and semipolar nitrides have attracted much attention because their usage leads to the elimination of the quantum-confined Stark effect and higher optical gains in this wavelength region. Since the breakthrough in the homoepitaxial growth technology for them, many nonpolar m -plane devices such as mW-class blue light-emitting diodes, violet 405 nm LDs, blue 460 nm LDs, and blue-green LDs beyond 490 nm have been announced. Advantages such as small blueshift and high slope efficiency (high output power to injected current ratio) have been confirmed for the first time in m -plane LDs beyond the blue region. On the other hand, the semipolar plane is also a candidate for green LDs. The pulsed operation of semipolar (1011) and (1122) violet LDs and lasing for a (1122) LD at 514 nm by optical pumping also have been reported. Such rapid progress in this research field will be reviewed.

Piezoelectric microelectromechanical systems (MEMS) offer the opportunity for high-sensitivity sensors and large displacement, low-voltage actuators. In particular, recent advances in the deposition of perovskite thin films point to a generation of MEMS devices capable of large displacements at complementary metal oxide semiconductor-compatible voltage levels. Moreover, if the devices are mounted in mechanically noisy environments, they also can be used for energy harvesting. Key to all of these applications is the ability to obtain high piezoelectric coefficients and retain these coefficients throughout the microfabrication process. This article will review the impact of composition, orientation, and microstructure on the piezoelectric properties of perovskite thin films such as PbZr1−xTixO3 (PZT). Superior piezoelectric coefficients (e31, f of −18 C/m2) are achieved in {001}-oriented PbZr0.52Ti0.48O3 films with improved compositional homogeneity on Si substrates. The advent of such high piezoelectric responses in films opens up a wide variety of possible applications. A few examples of these, including low-voltage radio frequency MEMS switches and resonators, actuators for millimeter-scale robotics, droplet ejectors, energy scavengers for unattended sensors, and medical imaging transducers, will be discussed.

Over decades of effort, investigations of the intrinsic phase transition behavior of nanoscale ferroelectric structures have been greatly complicated by materials processing variations and by the common and uncontrolled occurrence of spacecharge, which interacts directly with the polarization and can obscure fundamental behavior. These challenges have largely been overcome, and great progress in understanding the details of this class of phase transitions has been made, largely based on advances in the growth of high-quality, epitaxial ferroelectric films and in the theory and simulation of ferroelectricity. Here we will discuss recent progress in understanding the ferroelectric phase transition in a particular class of model systems: nanoscale perovskite thin-film heterostructures. The outlook for ferroelectric technology based on these results is promising, and extensions to laterally confined nanostructures will be described.