We report the pressure (P) dependent Curie temperature, Tc (P) in a FeCoNiCuMn high entropy alloy (HEA). We analyze Tc (P) in terms of d-orbital contraction to explain changes in magnetic exchange interactions (Jex). Considerations of the d-radius contraction inferred from the composition dependence of Tc in γ-Fe-Ni are combined with experimental data for P-dependent lattice constants and magnetic measurements of Tc (P), to calculate contributions of atomic spacing and d-orbital radii to Jex. We show the d-orbital contraction with P captures most of the Tc variation in this alloy.

This paper addresses what we call the investment question: Under what plausible circumstances, if any, can variable renewable energy (VRE, and solar photovoltaic (PV) in particular) be a good investment? Although VRE has been growing rapidly world-wide, it is generally subsidized. Under what cost and market conditions can solar PV flourish without subsidy? We employ solar insolation and market price data from the U.S. and from Germany to gain insight into the investment question. We find that unsubsidized solar PV is or may soon be a justifiable investment, but that market arrangements may play a crucial role in determining success. We end by sketching a proposal that amounts to a reformed capacity market that would afford participation of solar PV.

As measured standardly by levelized cost of energy (LCOE), onshore wind and utility scale solar PV (photovoltaic) have been rapidly declining in cost and are now reported to be the cheapest ways of generating electric power. While this is indisputably a welcome development, the fact that renewables in general --- wind and solar in particular --- are variable and available only intermittently makes LCOE a quite incomplete, perhaps even misleading, measure of value because it neglects the system cost of accommodating renewables for the sake of meeting demand and keeping the grid in balance. The additional cost of building and employing peaker plants (mainly fueled by natural gas), which serve as backup and reserve and hence are often idle, has led many observers to pessimistic conclusions about the economic viability of very high levels of penetration by renewable sources of energy.

Containerless processing of YBa2Cu3O7−δ was performed using an aero-acoustic levitation technique. Upon solidification from the liquid, spheres of size 2.5 mm diameter undercooled and recalesced, forming tetragonal YBa2Cu3O7−δ directly from the melt. Subsequent to solidification processing, these samples were annealed to single phase YBa2Cu3O7−δ with orthorhombic symmetry as indicated by powder XRD, SQUID magnetometer measurements indicate a sharp superconducting transition at approximately 85 K. Magnetic Jc values, calculated using the Bean critical state model, indicate that the spheres can carry critical current densities on the order of 104 A cm−2. Microstructural characterization has been performed on both the as-solidified and annealed spheres.

Due to the highly anisotropic properties of BSCCO superconductors, the bulk properties of these materials can be greatly affected by preferential orientation. Substantial c-axis orientation normal to the desired direction of current flow has been demonstrated by centrifugally slip casting lead-doped BSCCO-2223. The strong preferred orientation developed in the centrifugally slip-cast material demonstrates high critical current potential.

Films of Yba 2 Cu 3 O 7−δ (YBCO) were grown on (001), exact and vicinal (110), and (111) SrTiO 3 single crystal substrates by pulsed laser deposition, and evaluated by x-ray diffraction and scanning force microscopy (AFM). It was observed that the YBCO was always epitaxially aligned to the substrate with the [001] ( c -axis) parallel to a substrate cube axis direction. For the exact (001), (110), and (111) surfaces, there were one, two, and three orientations, respectively. For the vicinal (110) surfaces, however, there was usually only one discernible c -axis orientation, corresponding to a single {013} film surface orientation. The reduction of the (110) surface twofold symmetry by use of a vicinal substrate thus allowed controlled growth of a YBCO single crystal with an inclined c -axis orientation.

Polarization versus applied field (P-E) hysteresis loop measurements on Pb(Zr, Ti)O3 (PZT) thin films were performed using a controlled-atmosphere probe station. Measurements were made using two different capacitor configurations, each producing differing results. The capacitor configurations included using either the typical arrangement of two top electrodes (planar) or an arrangement using contacts to the top and the bottom electrodes (sandwich). The films included PZT films deposited using pulsed laser deposition (PLD) and commercially-available rfsputtered PZT thin films. Qualitatively similar results were obtained for both types of films. For both PLD and Ramtron PZT films, translation of ferroelectric hysteresis loops along the polarization axis was observed for sandwich capacitors. The magnitude of this voltage was strongly dependent on the partial pressure of oxygen at room temperature. Translations were not observed for the same films using the planar capacitor configuration. However, for both sandwich and planar configurations, the thin film capacitance was sensitive to changes in pO2.

A nonlinear boundary-value problem for the equilibrium of a pressurized magnetoelastic membrane acted upon by an applied magnetic field is derived from three-dimensional magnetoelasticity. The model is specified entirely by differential equations in the limit of weak material magnetization, these replacing the integro-differential equations of the general theory. The model is further specialized to axisymmetry, and several problems of technical interest are solved numerically.

In a previous study (Barham et al 2007 Acta Mech. 191 1–19), the finite deformation of a circular magnetoelastic membrane in an axisymmetric dipole field was calculated by specializing the equations of three-dimensional magnetoelastic equilibrium. The predicted response was found to be similar to the classical limit-point instability occurring in analogous purely mechanical problems. A limit-point instability occurs under conditions corresponding to the incipient non-existence of equilibria. Under such conditions the body is necessarily on the verge of a dynamical state. In the present setting, this corresponds to the occurrence of a maximum in the equilibrium deflection of the membrane with respect to applied field strength and proximity of the field source. The earlier conjecture of a limit-point instability, advanced in Barham et al (2007 Acta Mech. 191 1–19), is confirmed in the present work by using a variational method based on an adaptation of the energy criterion of elastic stability to the magnetoelastic setting.

Continued advances in the design of ignition targets have stimulating new development paths for target fabrication, with potentially important simplifications for fielding cryogenic ignition targets for the National Ignition Facility. Including graded dopants in ablators as well as optimizing capsule and fuel layer dimensions increase implosion stability. This has led to developments of micron-scale fill tubes to fill and field the targets. Rapid progress has been made in development of the graded dopant layers in capsules as well as their characterization, in fabrication methods for micro-fill-tubes, and in fuel fill control with these fill tubes. Phase-contrast x-ray radiography has allowed characterization of fuel layers in beryllium targets. This target development program includes participation from General Atomics, Lawrence Livermore National Laboratory, and Los Alamos National Laboratory.

First, we review earlier studies reporting possible magnetic characteristics for radiation defects in Pu. We then report, for {alpha}-Pu, two studies of the excess magnetic susceptibility (EMS) due to radiation damage, as a function of time and temperature. We have observed several annealing stages associated with the EMS of the accumulated self-damage and we report that annealing begins at {approx}31K, while below that temperature the displacement damage from self-irradiation of the Pu alpha particle emission and the U recoil are immobile. A detailed investigation was made of this EMS well below the first annealing stage as a function of temperature (2K < T < 15K) and time in a magnetic field of 2T. A linear increase in magnetic susceptibility is seen as a function of time for all isotherms. The excess susceptibility per alpha decay, determined from a linear fit of the slope of the time dependent EMS, is reasonably described with a Curie-Weiss law exhibiting a small negative Weiss temperature. We conclude by describing some future experiments in light of the present results.

Resonant inelastic soft X-ray scattering is a developing technique well suited to the study of correlation effects in complex materials. We briefly describe its potential for materials science and illustrate its sensitivity with a study of elementary excitations at Cu sites in YBa2Cu3O7−δ as a function of oxygen content. High resolution measurements at the Cu 2p edge reveal structure that, with the help of theoretical models, can be interpreted as due to d–d excitations of the type 3d (x2−y2) to 3d (3z2−r2), Zhang–Rice singlets, and changes in the Cu spin configuration.

This project was intended to advance the science of surface bonding in order to provide the functionality demanded by target fabrication requirements, as well as similar needs in other fields of importance to LLNL. We have developed and demonstrated a very powerful capability, i.e. 'single molecule force spectroscopy', that allows the strength of individual chemical bonds to be measured. This project focused on long chain molecules that are covalently bound to surfaces on one end and have complementary reactive groups that have the potential for bridging between surfaces. In biological systems, long chain tethers provide the mechanism for adhesion between dissimilar surfaces, e.g. bacteria adhesion to cells, and were found useful for developing the methodology. Polymer tethers offer the means to bridge across finite surface roughness and have the potential of forming thin, well-characterized bonds on a variety of surfaces.

Continued advances in the design of ignition targets have stimulating new development paths for target fabrication, with potentially important simplifications for fielding cryogenic ignition targets for the National Ignition Facility. Including graded dopants in ablators as well as optimizing capsule and fuel layer dimensions increase implosion stability. This has led to developments of micron-scale fill tubes to fill and field the targets. Rapid progress has been made in development of the graded dopant layers in capsules as well as their characterization, in fabrication methods for micro-fill-tubes, and in fuel fill control with these fill tubes. Phase-contrast x-ray radiography has allowed characterization of fuel layers in beryllium targets. This target development program includes participation from General Atomics, Lawrence Livermore National Laboratory, and Los Alamos National Laboratory.