Femtosecond Double-Pulse Laser Ablation and Deposition of Co-Doped ZnS Thin Films.

Nanostructured thin films of Co-doped zinc sulfide were synthesized through femtosecond pulsed laser deposition. The scheme involved ablation of physically mixed Co and ZnS with pairs of ultrashort pulses separated in time in the 0-300 ps range. In situ monitorization of the deposition process was carried out through a simultaneous reflectivity measurement.

Synthesis and Electron Microscopy Study of the Quaternary Misfit Layer Chalcogenides {(Bi,Nd)S}CrS and {(Pb,Nd)Se}(NbSe).

In the present work, two compounds, in the Bi-Nd-Cr-S and Pb-Nd-Nb-Se systems, not reported to date were synthesized. The chemical composition and the structural determination of these complex compounds, at atomic resolution, was performed through conventional and aberration-corrected electron microscopy including selected area electron diffraction, high resolution (HR) transmission electron microscopy (TEM), HR scanning TEM, and the analytical associated techniques X-ray energy-dispersive spectroscopy and electron energy-loss spectroscopy. The average compositions are [(Bi,Nd)S]CrS and [(Pb,Nd)Se](NbSe), respectively.

Organometallic-Derived Carbon (ODC)-Metal Nano-Oxide Composites as Improved Electrode Materials for Supercapacitors.

In the search for the new generation of electrochemical energy storage materials, a novel and straightforward synthetic route for porous carbons and metal oxide nanoparticle composites based on the chlorination of the organometallic compounds Ni(CH) and Mn(CHO) at moderate temperatures, followed by hydrothermal treatment, has been developed. Electrochemical measurements in a three-electrode configuration show that, in both composites NiO@ODC and MnO@ODC, a synergistic effect between the capacitive and pseudocapacitive energy storage mechanisms is observed, thereby improving their electrochemical performance vs pure carbon materials. Electrochemical evaluation of symmetric cells gave gravimetric capacitances of 124 and 130 F g for NiO@ODC and MnO@ODC, respectively.

Crystal Structures at Atomic Resolution of the Perovskite-Related GdBaMnFeO and Its Oxidized GdBaMnFeO.

Perovskite-related GdBaMnFeO and the corresponding oxidized phase GdBaMnFeO, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+.

Mechanosensitive Gold Colloidal Membranes Mediated by Supramolecular Interfacial Self-Assembly.

The ability to respond toward mechanical stimuli is a fundamental property of biological organisms at both the macroscopic and cellular levels, yet it has been considerably less observed in artificial supramolecular and colloidal homologues. An archetypal example in this regard is cellular mechanosensation, a process by which mechanical forces applied on the cell membrane are converted into biochemical or electrical signals through nanometer-scale changes in molecular conformations. In this article, we report an artificial gold nanoparticle (Au NP)-discrete π-conjugated molecule hybrid system that mimics the mechanical behavior of biological membranes and is able to self-assemble into colloidal gold nanoclusters or membranes in a controlled and reversible fashion by changing the concentration or the mechanical force (pressure) applied.

Microwave-Assisted Synthesis, Microstructure, and Magnetic Properties of Rare-Earth Cobaltites.

The series of perovskite rare-earth (RE) doped cobaltites (RE)CoO (RE = La-Dy) was prepared by microwave-assisted synthesis. The crystal structure undergoes a change of symmetry depending on the size of the RE cation. LaCoO is rhombohedral, S.

Double Double Cation Order in the High-Pressure Perovskites MnRMnSbO6.

Cation ordering in ABO3 perovskites adds to their chemical variety and can lead to properties such as ferrimagnetism and magnetoresistance in Sr2 FeMoO6 . Through high-pressure and high-temperature synthesis, a new type of "double double perovskite" structure has been discovered in the family MnRMnSbO6 (R=La, Pr, Nd, Sm). This tetragonal structure has a 1:1 order of cations on both A and B sites, with A-site Mn(2+) and R(3+) cations ordered in columns and Mn(2+) and Sb(5+) having rock salt order on the B sites.

Ordering effects in the crystal structure and electrochemical properties of the Gd0.5Ba0.5Mn0.5Fe0.5O3-δ perovskite.

Layered-type ordering and oxygen vacancies ordering are revealed in GdBaMnFeO(6-δ) perovskite. Selected area electron diffraction and high-resolution transmission electron microscopy results indicate a modulation of the crystal structure. Ba and Gd ordering in (001)(p) layers is confirmed by high angle annular dark field scanning transmission electron microscopy and electron energy-loss spectroscopy.

Synthesis, structures and magnetic properties of the dimorphic Mn2CrSbO6 oxide.

The perovskite polymorph of Mn(2)CrSbO(6) compound has been synthesized at 8 GPa and 1473 K. It crystallizes in the monoclinic P21/n space group with cell parameters a = 5.2180 (2) Å, b = 5.

Order, disorder and structural modulations in Bi-Fe-W-O-Br Sillén-Aurivillius intergrowths.

Transmission electron microscopy observations on a new complex oxybromide with nominal composition Bi(4)Fe(1/3)W(2/3)O(8)Br, heated at high temperature, reveal the transformation of its basic structure yielding two types of crystals. The first crystal type shows ordered and disordered extended defects leading to a new family of intergrowths between one Sillén block and n Aurivillius blocks and occasionally between one Aurivillius block and n Sillén blocks. The second type presents a compositionally modulated structure, determined by electron diffraction, with an average composition Bi(4)Fe(1/2)W(1/2)O(8 - delta)Br and unit-cell parameters a = (1/gamma) 3.

Electron microscopy characterization of nanostructured carbon obtained from chlorination of metallocenes and metal carbides.

In this work we report some new well-defined carbon nanostructures produced by direct chlorination of metallocenes (ferrocene and cobaltocene) and NbC, at temperatures from 100 to 900 degrees C. Thus, amorphous carbon nanotubes with variable dimensions depending on reaction temperature were produced from ferrocene. When cobaltocene is the carbon precursor the main product are solid amorphous nanospheres.

Statistical estimation of atomic positions from exit wave reconstruction with a precision in the picometer range.

The local structure of Bi4W2/3Mn1/3O8Cl is determined using quantitative transmission electron microscopy. The electron exit wave, which is closely related to the projected crystal potential, is reconstructed and used as a starting point for statistical parameter estimation. This method allows us to refine all atomic positions on a local scale, including those of the light atoms, with a precision in the picometer range.