Effect of Solvent Composition on Non-DLVO Forces and Oriented Attachment of Zinc Oxide Nanoparticles.

Oriented attachment (OA) occurs when nanoparticles in solution align their crystallographic axes prior to colliding and subsequently fuse into single crystals. Traditional colloidal theories such as DLVO provide a framework for evaluating OA but fail to capture key particle interactions due to the atomistic details of both the crystal structure and the interfacial solution structure. Using zinc oxide as a model system, we investigated the effect of the solvent on short-ranged and long-ranged particle interactions and the resulting OA mechanism.

Spontaneous Lithiation of Binary Oxides during Epitaxial Growth on LiCoO.

Epitaxial growth is a powerful tool for synthesizing heterostructures and integrating multiple functionalities. However, interfacial mixing can readily occur and significantly modify the properties of layered structures, particularly for those containing energy storage materials with smaller cations. Here, we show a two-step sequence involving the growth of an epitaxial LiCoO cathode layer followed by the deposition of a binary transition metal oxide.

Structure, Magnetism, and the Interaction of Water with Ti-Doped FeO Surfaces.

The functionality of magnetite, FeO, for catalysis and spintronics applications is dependent on the molar ratio of Fe and Fe and their distribution at the surface. In turn, this depends on a poorly understood interplay between crystallographic orientation, dopants, and the reactive adsorption of atmospheric species such as water. Here, (100)-, (110)-, and (111)-oriented films of titano-magnetite, FeTiO, were grown by pulsed laser deposition and their composition, valence distribution, magnetism, and interaction with water were studied by ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and X-ray magnetic circular dichroism.

Direct Visualization of Li Dendrite Effect on LiCoO Cathode by In Situ TEM.

Nonuniform and highly localized Li dendrites are known to cause deleterious and, in many cases, catastrophic effects on the performance of rechargeable Li batteries. However, the mechanisms of cathode failures upon contact with Li metal are far from clear. In this study, using in situ transmission electron microscopy, the interaction of Li metal with well-defined, epitaxial thin films of LiCoO , the most widely used cathode material, is directly visualized at an atomic scale.

Reduced Magnetism in Core-Shell Magnetite@MOF Composites.

The magnetic susceptibility of synthesized magnetite (FeO) microspheres was found to decline after the growth of a metal-organic framework (MOF) shell on the magnetite core. Detailed structural analysis of the core-shell particles using scanning electron microscopy, transmission electron microscopy, atom probe tomography, andFe-Mössbauer spectroscopy suggests that the distribution of MOF precursors inside the magnetic core resulted in the oxidation of the iron oxide core.

Coupled Lattice Polarization and Ferromagnetism in Multiferroic NiTiO Thin Films.

Polarization-induced weak ferromagnetism (WFM) was demonstrated a few years back in LiNbO-type compounds, MTiO (M = Fe, Mn, Ni). Although the coexistence of ferroelectric polarization and ferromagnetism has been demonstrated in this rare multiferroic family before, first in bulk FeTiO, then in thin-film NiTiO, the coupling of the two order parameters has not been confirmed. Here, we report the stabilization of polar, ferromagnetic NiTiO by oxide epitaxy on a LiNbO substrate utilizing tensile strain and demonstrate the theoretically predicted coupling between its polarization and ferromagnetism by X-ray magnetic circular dichroism under applied fields.

Metal-insulator photocathode heterojunction for directed electron emission.

We use angle-resolved photoemission under ultraviolet laser excitation to demonstrate that the electron emission properties of Ag(001) can be markedly enhanced and redirected along the surface normal by the deposition of a few monolayers of epitaxial MgO. We observe new low-binding energy states with small spreads in their surface parallel momenta as a result of MgO/Ag(001) interface formation. Under 4.

Manganese doping of magnetic iron oxide nanoparticles: tailoring surface reactivity for a regenerable heavy metal sorbent.

A method for tuning the analyte affinity of magnetic, inorganic nanostructured sorbents for heavy metal contaminants is described. The manganese-doped iron oxide nanoparticle sorbents have a remarkably high affinity compared to the precursor material. Sorbent affinity can be tuned toward an analyte of interest simply by adjustment of the dopant quantity.

Magnetotransport properties of high quality Co:ZnO and Mn:ZnO single crystal pulsed laser deposition films: pitfalls associated with magnetotransport on high resistivity materials.

The electrical resistivity values for a series of pure and doped (Co, Mn, Al) ZnO epitaxial films grown by pulsed laser deposition were measured with equipment designed for determining the direct current resistivity of high resistance samples. Room-temperature resistances ranging from 7 x 10(1) to 4 x 10(8) Omega/sq were measured on vacuum-reduced cobalt-doped ZnO, (Al,Co) co-doped ZnO, pure cobalt-doped ZnO, Mn-doped ZnO, and undoped ZnO. Using a four-point collinear geometry with gold spring-loaded contacts, resistivities were measured from 295 to 5 K for resistances of < approximately 10(12) Omega/sq.

High-performance, superparamagnetic, nanoparticle-based heavy metal sorbents for removal of contaminants from natural waters.

We describe the synthesis and characterization of high-performance, superparamagnetic, iron oxide nanoparticle-based, heavy metal sorbents, which demonstrate excellent affinity for the separation of heavy metals in contaminated water systems (i.e., spiked Columbia River water).

Antibody recognition force microscopy shows that outer membrane cytochromes OmcA and MtrC are expressed on the exterior surface of Shewanella oneidensis MR-1.

Antibody recognition force microscopy showed that OmcA and MtrC are expressed on the exterior surface of living Shewanella oneidensis MR-1 cells when Fe(III), including solid-phase hematite (Fe(2)O(3)), was the terminal electron acceptor. OmcA was localized to the interface between the cell and mineral. MtrC displayed a more uniform distribution across the cell surface.

Specific bonds between an iron oxide surface and outer membrane cytochromes MtrC and OmcA from Shewanella oneidensis MR-1.

Shewanella oneidensis MR-1 is purported to express outer membrane cytochromes (e.g., MtrC and OmcA) that transfer electrons directly to Fe(III) in a mineral during anaerobic respiration.