Bifunctional catalytic/magnetic Ni@Ru core-shell nanoparticles

Core-shell structured Ni@Ru bimetallic nanoparticles are demonstrated as a bifunctional nanoplatform system for the hydrolysis reaction of ammonia-borane and also for magnetic separation.     

Coexistence of antiferromagnetic and ferromagnetic orders at remanent state in epitaxial multiferroic Bi2FeCrO6 nanostructures

We report the local electronic and magnetic properties of Bi(2)FeCrO(6) nanostructures by element-specific polarized x-ray techniques. Sizable magnetic ordering in the remanent state is observed at room temperature for both Fe and Cr ions. The Bi(2)FeCrO(6) system offers an example of d(5)-d(3) magnetic superexchange interaction with a magnetic order for both Fe and Cr, which are both formally in the +?3 valence state. The results suggest a coexistence of antiferromagnetic and ferromagnetic superexchange interaction between Fe and Cr spins in the nanostructures at the remanent state and at room temperature.     

Polar properties of hydrothermally synthesized BiFeO3 thin films

Multiferroic bismuth ferrite (BiFeO₃) has attracted considerable attention due to applications related to the bulk photovoltaic effect in which the direction of polarization determines the direction of the photocurrent. Epitaxial thin films are produced by means of techniques that usually require high temperature processes. The hydrothermal method can be seen as an alternative route to obtain highly textured thin films in quantities compatible with batch processing; nevertheless, the structural, dielectric and electric properties are generally affected by the presence of hydrogen and other reaction by-products. In this work, functional and highly textured BiFeO₃ films were successfully produced on metallic SrTiO₃:Nb (0.5 wt.%) (100) substrates via hydrothermal synthesis. X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) were used to analyze the structural properties of the films. Piezoresponse Force Microscopy (PFM) and Photoconductive Atomic Force Microscopy (Pc-AFM) were used to determine their functional properties. We show the polarization switching and confirm the presence of the bulk photovoltaic effect for the first time in hydrothermally synthesized BiFeO₃.     

Characterization of individual multifunctional nanoobjects with restricted geometry

Anisotropic nanostructures such as nanowires (NWs)/nanotubes and nanometer-sized islands are the subject of intense research efforts due to several interesting phenomena observed to occur in confined geometries with a high aspect ratio and/or reduced size. Understanding and controlling the mechanical and electromechanical behaviors of these nanostructures are crucial for the practical implementation of such building blocks as active or passive components in nanodevices. Recent progresses toward the characterization of individual one-dimensional (NWs and nanotubes) and two-dimensional (islands) functional nanoscale objects of piezoelectric and ferroelectric (BaTiO₃, Bi₄Ti₃O₁₂ (BiT), and NaNbO₃) and multiferroics (BiFeO₃ and Bi₂FeCrO₆ (BFCO)) are presented. These nanoobjects have been characterized using scanning probe microscopy-based techniques, combined with various modulation schemes for enhanced sensing capabilities. The most remarkable results include: ferroelectricity of NaNbO₃/Nb₂O₅ nanotube heterostructures, negative piezoelectric coefficient in highly anisotropic BiT mesoscopic rods, and preservation of the multiferroic character of epitaxial BFCO nanoislands.     

Premature degradation study of a cathode-supported solid oxide electrolysis cell

Journal of Solid State Electrochemistry - Degradation-related issues are among the main limitations to make solid oxide electrolysis cells (SOEC) meet performance targets economically viable for...     

Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis

Journal of Solid State Electrochemistry - The accelerated degradation of a commercial LSCF/YDC/YSZ/Ni-YSZ solid oxide electrolyzer cell...     

Understanding the development of mathematical work in the context of the classroom

ZDM – Mathematics Education - According to our approach to mathematics education, the optimal aim of the teaching of mathematics is to assist students in achieving efficient mathematical...     

Multiferroic properties-structure relationships in epitaxial Bi(2)FeCrO(6) thin films: recent developments

We report recent developments in the growth and characterization of epitaxial Bi(2)FeCrO(6) (BFCO) thin films. The body of experimental data stemming mostly from our investigations, and also considering the few available reports from other groups, allows us to explain the origin(s) of the thickness dependence of the multiferroic properties observed. A drastic reduction of the films' magnetization is observed for film thicknesses larger than 80 nm. This decrease in magnetization is attributed to the formation of defects, such as antisites and antiphase boundaries, in the BFCO films. The change in magnetization is accompanied by a BFCO cell expansion, a consequence of the volume increase of the oxygen octahedra surrounding the Fe cations induced by the defects. BFCO films are ferroelectric for all the thicknesses investigated, ferroelectricity being only moderately affected by the film thickness.