Gd-doped CeO(2) exhibits an anomalously large electrostriction effect generating stress that can reach 500 MPa. In situ XANES measurements indicate that the stress develops in response to the rearrangement of cerium-oxygen vacancy pairs. This mechanism is fundamentally different from that of materials currently in use and suggests that Gd-doped ceria is a representative of a new family of high-performance electromechanical materials.

Realizing laterally continuous ultra-thin gold films on transparent substrates is a challenge of significant technological importance. In the present work, formation of ultra-thin gold films on fused silica is studied, demonstrating how suppression of island formation and reduction of plasmonic absorption can be achieved by treating substrates with (3-mercaptopropyl) trimethoxysilane prior to deposition. Void-free films with deposition thickness as low as 5.4 nm were realized and remained structurally stable at room temperature. Based on detailed structural analysis of the films by specular and diffuse X-ray reflectivity measurements, it is shown that optical transmission properties of continuous ultra-thin films can be accounted for 2 using the bulk dielectric function of gold. However, it is important to take into account the non-abrupt transition zone between the metal and the surrounding dielectrics, which extends through several lattice constants for the laterally continuous ultra-thin films (film thickness below 10 nm). This results in a significant reduction of optical transmission, as compared to the case of abrupt interfaces. These findings imply that the atomic-scale interface structure plays an important role when continuous ultra-thin films are considered, e.g., as semitransparent electrical contacts, since optical transmission deviates significantly from the theoretical predictions for ideal films.

The kinetics of point‐defect association/dissociation reactions in Ce0.8Gd0.2O1.9 and their influence on the crystal lattice parameter are investigated by monitoring thermally induced stress and strain in substrate‐ and self‐supported thin films. It is found that, in the temperature range of 100–180 °C, the lattice parameter of the substrate‐supported films and the lateral dimensions of annealed, self‐supported films both exhibit a hysteretic behavior consistent with dissociation/association of oxygen vacancy–aliovalent dopant complexes. This leads to strong deviation from linear elastic behavior, denoted in the authors' previous work as the “chemical strain” effect. At room temperature, the equilibrium state of the point defects is reached within a few months. During this period, the lattice parameter of the substrate‐supported films spontaneously increases, while the self‐supported films are observed to transform from the flat to the buckled state, indicating that formation of the dopant–vacancy complex is associated with a volume increase. The unexpectedly slow kinetics of establishing the defect equilibrium at room temperature can explain the fact that, depending on the sample history, the “observable” lattice parameters of Ce0.8Gd0.2O1.9, as reported in the literature, may differ from one another by a few tenths of a percent. These findings strongly suggest that the lattice parameter of the materials with a large concentration of interacting point defects is a strong function of time and material preparation route.

In this study, multi-phase borosilicate-based glass-ceramics were investigated as an alternative waste form for immobilizing non-fissionable products from used nuclear fuel. Currently, borosilicate glass is the waste form selected for immobilization of this waste stream, however, the low thermal stability and solubility of MoO 3 in borosilicate glass translates into a maximum waste loading in the range 15-20 mass%. Glass-ceramics provide the opportunity to target chemically durable crystalline phases, e.g., powellite, oxyapatite, celsian, and pollucite that will incorporate MoO 3 as well as other waste components such as lanthanides, alkalis, and alkaline earths at levels twice the solubility limits of a single-phase glass. In addition a glassceramic could provide higher thermal stability, depending upon the properties of the crystalline and amorphous phases. Here, glass-ceramics were synthesized at waste loadings of 42, 45, and 50 mass% with the following glass additives: B 2 O 3 , Al 2 O 3 , CaO, and SiO 2 by slow-cooling from a glass melt. Glass-ceramics were characterized in terms of phase assemblage, morphology, and thermal stability. Only two of the targeted phases, powellite and oxyapatite, were observed, along with lanthanide-borosilicate and cerianite. Results of this initial investigation show promise of glass-ceramics as a potential waste form to replace single-phase borosilicate glass.