4 research outputs found
Intergrowth and Interfacial Structure of Biomimetic FluorapatiteāGelatin Nanocomposite: A Solid-State NMR Study
The model system fluorapatiteāgelatin
allows mimicking the
formation conditions on a lower level of complexity compared to natural
dental and bone tissues. Here, we report on solid-state NMR investigations
to examine the structure of fluorapatiteāgelatin nanocomposites
on a molecular level with particular focus on organicāinorganic
interactions. Using <sup>31</sup>P, <sup>19</sup>F, and <sup>1</sup>H MAS NMR and heteronuclear correlations, we found the nanocomposite
to consist of crystalline apatite-like regions (fluorapatite and hydroxyfluorapatite)
in close contact with a more dissolved (amorphous) layer containing
first motifs of the apatite crystal structure as well as the organic
component. A scheme of the intergrowth region in the fluorapatiteāgelatin
nanocomposite, where mineral domains interact with organic matrix,
is presented
Redox Route from Inorganic Precursor Li<sub>2</sub>C<sub>2</sub> to Nanopatterned Carbon
We
present the synthesis route to carbon with hierarchical morphology
on the nanoscale. The structures are generated using crystalline orthorhombic
lithium carbide (Li<sub>2</sub>C<sub>2</sub>) as precursor with nanolamellar
organization. Careful treatment by SnI<sub>4</sub> oxidizes carbon
at the fairly low temperature of 80 Ā°C to the elemental state
and keeps intact the initial crystallite shape, the internal lamellar
texture of particles, and the lamellae stacking. The reaction product
is amorphous but displays in the microstructure parallel band-like
arrangements with diameters in the range of 200ā500 nm. These
bands exhibit internal fine structure made up by thin strips of about
60 nm width running inclined with respect to the long axis of the
band. The stripes of neighboring columns sometimes meet and give rise
to arrow-like arrangements in the microstructure. This is an alternative
preparation method of nanostructured carbon from an inorganic precursor
by a chemical redox route without applying physical methods such as
ion implantation, printing, or ablation. The polymerization reaction
of the triple bond of acetylide anions gives rise to a network of
carbon sp<sup>2</sup> species with statistically sized and distributed
pores with diameters between 2 and 6 Ć
resembling zeolite structures.
The pores show partially paracrystal-like ordering and may indicate
the possible formation of carbon species derived from graphitic foams
Synthesis and Three-Dimensional Magnetic Field Mapping of Co<sub>2</sub>FeGa Heusler Nanowires at 5 nm Resolution
We
present the synthesis of Co<sub>2</sub>FeGa Heusler nanowires and
the results of our investigations on their three-dimensional (3D)
electric and magnetic internal and external fields mapped by electron
holographic tomography (EHT). These fields will be of great importance
in next-generation nanomagnets integrated in spintronics and memory
devices. The Co<sub>2</sub>FeGa nanowires with a <i>L2</i><sub>1</sub> ordered structure are prepared by a SBA-15 silica-assisted
method. The magnetic dipole-like stray fields of several Co<sub>2</sub>FeGa nanowires are revealed by holographically reconstructed phase
images. Based on the measured magnetic phase shifts of an individual
nanowire and its 3D reconstruction using EHT, we obtain an internal
magnetic induction with a magnitude of 1.15 T and a nonmagnetic surface
layer of 10 nm thickness. Furthermore, we also reconstruct the 3D
distribution of the electrostatic potential of the same nanowire
Pd@Fe<sub>2</sub>O<sub>3</sub> Superparticles with Enhanced Peroxidase Activity by Solution Phase Epitaxial Growth
Compared
to conventional deposition techniques for the epitaxial
growth of metal oxide structures on a bulk metal substrate, wet-chemical
synthesis based on a dispersible template offers advantages such as
low cost, high throughput, and the capability to prepare metal/metal
oxide nanostructures with controllable size and morphology. However,
the synthesis of such organized multicomponent architectures is difficult
because the size and morphology of the components are dictated by
the interplay of interfacial strain and facet-specific reactivity.
Here we show that solution-processable two-dimensional Pd nanotetrahedra
and nanoplates can be used to direct the epitaxial growth of Ī³-Fe<sub>2</sub>O<sub>3</sub> nanorods. The interfacial strain at the PdāĪ³-Fe<sub>2</sub>O<sub>3</sub> interface is minimized by the formation of an
Fe<sub><i>x</i></sub>Pd ābuffer phaseā facilitating
the growth of the nanorods. The Ī³-Fe<sub>2</sub>O<sub>3</sub> nanorods show a (111) orientation on the Pd(111) surface. Importantly,
the Pd@Ī³-Fe<sub>2</sub>O<sub>3</sub> hybrid nanomaterials exhibit
enhanced peroxidase activity compared to that of isolated Fe<sub>2</sub>O<sub>3</sub> nanorods with comparable surface area because of a
synergistic effect for the charge separation and electron transport.
The metal-templated epitaxial growth of nanostructures via wet-chemical
reactions appears to be a promising strategy for the facile and high-yield
synthesis of novel functional materials