3,007 research outputs found
Direct observation of microscopic change induced by oxygen vacancy drift in amorphous TiO2 thin films
To clarify the resistive switching and failure mechanisms in Al/amorphous TiO2 /Al devices we investigate the microscopic change in amorphous titanium oxide films and interface layers after the set process according to film deposition temperatures. For low temperature (<150 ??C) samples, the thickness of top interface layer decreased after the set process due to the dissociation of a top interface layer by uniform migration of oxygen vacancies. Meanwhile, for high temperature samples, crystalline TiO phases emerged in the failed state, meaning the formation of conducting paths from the local clustering of oxygen vacancies in nonhomogeneous titanium oxide film.open221
Microscopic origin of bipolar resistive switching of nanoscale titanium oxide thin films
We report a direct observation of the microscopic origin of the bipolar
resistive switching behavior in nanoscale titanium oxide films. Through a
high-resolution transmission electron microscopy, an analytical TEM technique
using energy-filtering transmission electron microscopy and an in situ x-ray
photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at
top interface by an oxidation-reduction reaction between the titanium oxide
layer and the top Al metal electrode. We also found that the drift of oxygen
ions during the on/off switching induced the bipolar resistive switching in the
titanium oxide thin films.Comment: 10 pages, 4 figure
Electrical current suppression in Pd-doped vanadium pentoxide nanowires caused by reduction in PdO due to hydrogen exposure
Pd nanoparticle-doped vanadium pentoxide nanowires (Pd-VONs) were synthesized. Electrical current suppression was observed when the Pd-VON was exposed to hydrogen gas, which cannot be explained by the work function changes mentioned in previous report such as Pd-doped carbon nanotubes and SnO 2 nanowires. Using the x-ray photoelectron spectroscopy, we found that the reduction in PdO due to hydrogen exposure plays an important role in the current suppression of the Pd-VON.open4
Simple coordination complex-derived three-dimensional mesoporous graphene as an efficient bifunctional oxygen electrocatalyst
3D mesoporous graphene (mesoG) was synthesized from [Ni<inf>2</inf>(EDTA)] (EDTA = ethylenediaminetetraacetate). The material is comprised of interconnected 4 nm-sized hollow carbon shells composed of 3-4 layers of graphene and exhibits high bifunctional electrocatalytic activity as well as high durability for use in oxygen evolution and reduction reactions. This journal is ??? 2015 The Royal Society of Chemistryopen11
Machine-learning-assisted analysis of transition metal dichalcogenide thin-film growth
In situ reflective high-energy electron diffraction (RHEED) is widely used to
monitor the surface crystalline state during thin-film growth by molecular beam
epitaxy (MBE) and pulsed laser deposition. With the recent development of
machine learning (ML), ML-assisted analysis of RHEED videos aids in
interpreting the complete RHEED data of oxide thin films. The quantitative
analysis of RHEED data allows us to characterize and categorize the growth
modes step by step, and extract hidden knowledge of the epitaxial film growth
process. In this study, we employed the ML-assisted RHEED analysis method to
investigate the growth of 2D thin films of transition metal dichalcogenides
(ReSe2) on graphene substrates by MBE. Principal component analysis (PCA) and
K-means clustering were used to separate statistically important patterns and
visualize the trend of pattern evolution without any notable loss of
information. Using the modified PCA, we could monitor the diffraction intensity
of solely the ReSe2 layers by filtering out the substrate contribution. These
findings demonstrate that ML analysis can be successfully employed to examine
and understand the film-growth dynamics of 2D materials. Further, the ML-based
method can pave the way for the development of advanced real-time monitoring
and autonomous material synthesis techniques.Comment: 21 pages, 4 figure
Ultrathin titania coating for high-temperature stable SiO2/Pt nanocatalysts
The facile synthesis of silica supported platinum nanoparticles with ultrathin titania coating to enhance metal-support interactions suitable for high temperature reactions is reported, as thermal and structure stability of metal nanoparticles is important for catalytic reactions.close8
Flexible room-temperature NO2 gas sensors based on carbon nanotubes/reduced graphene hybrid films
We present a flexible room temperature NO2 gas sensor consisting of vertical carbon nanotubes (CNTs)/reduced graphene hybrid film supported by a polyimide substrate. The reduced graphene film alone showed a negligible sensor response, exhibiting abnormal N-P transitions during the initial NO2 injection. A hybrid film, formed by the growth of a vertically aligned CNT array (with CNTs 20 ??m in length) on the reduced graphene film surface, exhibited remarkably enhanced sensitivities with weak N-P transitions. The increase in sensitivity was mainly attributed to the high sensitivity of the CNT arrays. The outstanding flexibility of the reduced graphene films ensured stable sensing performances in devices submitted to extreme bending stress.open786
Drop-coated Titanium Dioxide Memristors
The fabrication of memristors by drop-coating sol-gel Ti(OH) solution
onto either aluminium foil or sputter-coated aluminium on plastic is presented.
The gel layer is thick, 37m, but both devices exhibit good memristance I-V
profiles. The drop coated aluminium foil memristors compare favourably with the
sputter-coated ones, demonstrating an expansion in the accessibility of
memristor fabrication. A comparison between aluminium and gold for use as the
sputter-coated electrodes shows that aluminium is the better choice as using
gold leads to device failure. The devices do not require a forming step.Comment: 9 figures. arXiv admin note: substantial text overlap with
arXiv:1106.629
- …