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Abstract: Nanotubes of ferroelectric lead titanate (PbTiO3) have been made by a template-assisted method. An equimolar Pb–Ti sol was dropped onto porous alumina membranes and penetrated into the channels of the template. Single-phase PbTiO3 perovskite nanotubes were obtained by annealing at 700°C for 6h. The nanotubes had diameters of 200–400nm with a wall thickness of approximately 20nm. Excess PbO or annealing in a Pb-containing atmosphere was not necessary in order to achieve single-phase PbTiO3 nanotubes. The influence of the heating procedure and the sol concentration is discussed. [Copyright &y& Elsevier]

The atomistic and electronic structure and oxygen stoichiometry of nanocomposites between alumina and graphene oxide were investigated by density functional theory calculations. The nanocomposite was described as interfaces between α-Al 2 O 3 (0001) surfaces and graphene oxide; the latter was defined with oxygen bound as epoxy groups and a C:O atomic ratio of 4:1. The optimized composite structure with 1–3 layers of graphene oxide in between Al 2 O 3 contains bridging Al O C bonds at the interface. Reduction of the composite was investigated by removal of oxygen from the interface Al O C bonds, within the graphene oxide layers and in Al 2 O 3 . It was found that removal of oxygen within the graphene oxide layers is essentially independent of the Al 2 O 3 interface, i.e., the same as in pure graphene oxide. Oxygen was, however, more strongly bound in the interface Al O C bonds by 0.80 eV, and reduction of graphene oxide to graphene is accordingly preferred within the graphene oxide layers rather than at the oxide interface. [ABSTRACT FROM AUTHOR]

Abstract: La0.58Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathodes have been deposited on proton-conducting BaCe0.2Zr0.7Y0.1O3−δ (BCZY27) electrolyte and studied in symmetric cells to investigate the cathode microstructure and electrochemical performance. Three different types of cathodes have been prepared: two prepared from a solution, infiltrated into a screen-printed BZCY27 porous backbone (4 and 12 infiltrations), and one prepared by spray pyrolysis onto a polished electrolyte. In all three cases, LSCF is obtained after annealing at 700°C for 2h. Analysis of the electrochemical impedance spectra between 450°C and 600°C in air, with varying p(H2O), reveals that the charge transfer contribution is the lowest for the backbone-infiltrated cathode while the oxygen dissociation/adsorption contribution is the lowest for the spray-pyrolyzed cathode. The area specific resistances increase with the water vapor pressure. The area specific resistances obtained are 0.61Ωcm2 and 0.89Ωcm2 at 600°C for the spray-pyrolyzed LSCF cell in dry and humidified air, respectively; the corresponding resistances are 0.63Ωcm2 and 0.98Ωcm2 for the 12 times infiltrated LSCF cell. These resistances are the lowest reported for LSCF cathodes on Ba(Ce,Zr)O3-based electrolytes and show the promise of low-temperature fabrication methods for these systems. [Copyright &y& Elsevier]