Dimension changes on the order of 0.1% or above in response to an applied voltage have been reported for many types of materials, including ceramics, polymers, and carbon nanostructures, but not, so far, for metals. We show that reversible strain amplitudes comparable to those of commercial piezoceramics can be induced in metals by introducing a continuous network of nanometer-sized pores with a high surface area and by controlling the surface electronic charge density through an applied potential relative to an electrolyte impregnating the pores.

Proton conduction related electrical dipole and space charge polarization in hydroxyapatite J. Appl. Phys. 112, 074901 (2012) Phase-field modeling of stress generation in electrode particles of lithium ion batteries Appl. Phys. Lett. 101, 133902 (2012) Simultaneous enhancement of electronic and Li+ ion conductivity in LiFePO4 Appl. Phys. Lett. 101, 033901 (2012) Sodium ionic conduction in complex hydrides with [BH4]− and [NH2]− anions Appl. Phys. Lett. 100, 203904 (2012) Defect chemistry of Ti-doped antiferroelectric Bi0.85Nd0.15FeO3The diffusion of oxygen in ultrafine grained, undoped monoclinic ZrO 2 was studied using 18 O as tracer and secondary ion mass spectroscopy profiling. Samples with a relative mass density of 97%-99% and average crystallite sizes of 80 or 300 nm were prepared from Zr by sputtering, inert-gas-condensation, oxidation, in situ consolidation of nanocrystalline (n-)ZrO 2 powder and subsequent pressureless sintering at 950 or 1050°C in vacuum. Volume and interface diffusivities were directly determined from the 18 O diffusion profiles in n-ZrO 2 in the type B and type A regime of interface diffusion. The diffusion of 18 O in interfaces in undoped n-ZrO 2 is 10 3 -10 4 times faster than in the bulk of the crystallites throughout the temperature range of 450 to 950°C studied. These diffusivities are independent of the crystallite size in the range of 70-300 nm. The activation energies Q V ϭ2.29 eV and Q B ϭ1.95 eV for the volume (Q V ) and interface diffusion (Q B ) are considerably higher than the diffusion activation energies found in the fast ion conductors Ca-or Y-stabilized ZrO 2 . Based on the present data on oxygen diffusion in ZrO 2 , the cation and anion diffusivities of other binary oxides are discussed.

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Nanoglasses are solids consisting of nanometer-sized glassy regions connected by interfaces having a reduced density. We studied the structure of Sc(75)Fe(25) nanoglasses by electron microscopy, positron annihilation spectroscopy, and small-/wide-angle X-ray scattering. The positron annihilation spectroscopy measurements showed that the as-prepared nanoglasses consisted of 65 vol% glassy and 35 vol% interfacial regions. By applying temperature annealing to the nanoglasses and measuring in situ small-angle X-ray scattering, we observed that the width of the interfacial regions increased exponentially as a function of the annealing temperature. A quantitative fit to the small-angle X-ray scattering data using a Debye-Bueche random phase model gave a correlation length that is related to the sizes of the interfacial regions in the nanoglass. The correlation length was found to increase exponentially from 1.3 to 1.7 nm when the sample temperature was increased from 25 to 230 °C. Using simple approximations, we correlate this to an increase in the width of interfacial regions from 0.8 to 1.2 nm, while the volume fraction of interfacial regions increased from 31 to 44%. Using micro-compression measurements, we investigated the deformation behavior of ribbon glass and the corresponding nanoglass. While the nanoglass exhibited a remarkable plasticity even in the annealed state owing to the glass-glass interfaces, the corresponding ribbon glass was brittle. As this difference seems not limited to Sc(75)Fe(25) glasses, the reported result suggest that nanoglasses open the way to glasses with high ductility resulting from the nanometer sized microstructure.

The single-component positron lifetime of 402 ps measured in C60-15-mole% C70 is compared to that in the other carbon allotropic forms graphite and diamond. From the decrease of the positron lifetime in the fullerite specimen with quasihydrostatic pressure it is concluded that the positron is annihilated on interstitial sites and not in the interior of the fullerene molecules.After the recent breakthrough in preparing macroscopic quantities' of C6p carbon molecules ("fullerenes") the solid-state properties of the molecular crystal ("fullerite") were studied.