Thermal decomposition of boehmite and bayerite has been studied by X-ray diffraction and by NMR and IR spectroscopies. Coordination and site distortion of Al polyhedra have been estimated by 27Al NMR spectroscopy while IR optical properties of transitional aluminas, η-, γ-, δ-, and θ-Al2O3 were derived from IR near-normal specular reflectance technique. In the low-temperature phases, aluminum vacancies are located in tetrahedral positions in γ-Al2O3 while in η-Al2O3 they are distributed at random between tetrahedral and octahedral positions. In addition, a small amount (5%) of pentahedrally coordinated aluminum was found in γ-alumina, which has been tentatively assigned to Al at the external surface of alumina particles. At 800 °C a notable increase in structural ordering was detected in both phases; in the case of η-Al2O3, this change accelerates the continuous transformation into θ-Al2O3 which is totally achieved at 1000 °C. On the contrary, γ-Al2O3, does not show any sign of transformation until 900 °C; at 950 °C pentahedral cations disappear and formation of θ-Al2O3 is detected by IR and NMR techniques. From 900 to 1200 °C, γ-, θ-, and α-Al2O3 coexist in samples obtained from boehmite. Above 1200 °C corundum is the only thermodynamically stable phase in both series of samples.

A novel capacitor devicewith a high, frequency‐independent dielectric constant has been fabricated by a simple powder processing route. A mixture of microparticles of ferroelectric BaTiO3 and de‐passivated metallic nickel was sintered to yield percolative composites in which the system of conducting particles separated by insulator layers (see Figure for an SEM image) exhibits a dielectric constant higher than that of either component.

The color of small gold rods changes dramatically when electrons are injected by chemical reductants. The longitudinal and transverse plasmon modes are both found to blue-shift, and the shift is larger for rods with larger aspect ratios. The color changes are visible to the eye for rods with aspect ratios around 2-3. It is found that the surface plasmon band is damped when charging becomes high. The effects are in qualitative agreement with a model in which the gold plasma frequency increases due to an increase in electron density.

correlated with surface chemistry, characterized by X-ray photoelectron spectroscopy. The surface texture, thickness, and elastic modulus of the films indicate potential for integration in semiconductor interconnects.

We propose a simple way to put in a common scale the h values of researchers working in different scientific ISI fields, so that the previsible misuse of this index for inter-areas comparison might be prevented, or at least, alleviated.

The activation energy involved in the motion of Li+ ions along the conduction channels of the NASICON framework has been determined from electrical conductivity measurements in samples of composition LiM2(PO4)3 and LiMM‘(PO4)3, where M and M‘ are Ge, Ti, Sn, and Hf, all compounds belonging to space group R3̄c. Two lithium sites, M1 and M2, inside the channels, can be distinguished. The sites are connected through triangular bottlenecks of oxygen atoms, and the size of the bottleneck has been estimated from refined and simulated structures for each composition. The plot of activation energy vs bottleneck size shows two regimes:  for sizes up to 2.04 Å the activation energy decreases steeply, but above 2.04 Å the activation energy is almost constant. These regimes are discussed on the basis of the effective Li+ ionic radius for the compounds analyzed.

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