Self-organized Ce(1-x)Gd(x)O(2-y) nanowire networks with very fast coarsening driven by attractive elastic interactions

Spontaneous Rippling and Subsequent Polymer Molding on Yttria-Stabilized Zirconia (110) Surfaces

Spontaneous nanoripple formation on (110) surfaces of yttria-stabilized zirconia, YSZ-(110), is achieved by diffusional surface doping with rare-earth oxides. Periodic arrays of parallel nanobars separated by channels (period ∼100 nm) grow out of the dopant sources, covering relatively wide areas of the surface (∼10 μm). The nanobars mound up on the surface by diffusion, exhibiting morphological uniformity and alignment, with their long axis lying parallel to the [11̅0] direction in the YSZ-(110) surface. The process for forming these nanobar arrays can be as simple as sprinkling of rare-earth oxide powder (dopant source) on YSZ-(110) surface and annealing in a high temperature air furnace. However, higher control on dopant dispersion on the surface is demonstrated with other techniques, including photolithography and inkjet printing. The ripple arrays extend anisotropically on the (110) surface, obeying the parabolic growth law, and showing principal values of the rate constant along [11̅0] (maximum) and [001] (minimum), as expected from the symmetry of the (110) surface. The self-patterned ceramic substrates are well-suited for pattern transfer by replica molding, as illustrated by single-step molding with polydimethylsiloxane (PDMS), which is a widely used biomaterial in cell-culture studies.

Orientation symmetry breaking in self-assembled Ce1−xGdxO2−ynanowires derived from chemical solutions

A novel approach to perform an independent study of the nucleation and coarsening of Ce_0.9Gd_0.1O_2−ynanowires is presented.

Nanoscale strain-induced pair suppression as a vortex-pinning mechanism in high-temperature superconductors

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centres in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa(2)Cu(3)O(7) matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.