scholarly journals Mimicking associative learning using an ion-trapping non-volatile synaptic organic electrochemical transistor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xudong Ji ◽  
Bryan D. Paulsen ◽  
Gary K. K. Chik ◽  
Ruiheng Wu ◽  
Yuyang Yin ◽  
...  
Keyword(s):  
Associative Learning ◽  
Photoelectron Spectroscopy ◽  
Near Infrared ◽  
Grazing Incidence ◽  
Ion Trapping ◽  
X Ray ◽  
Electrochemical Transistor ◽  
Electrochemical Devices ◽  
Conductance States ◽  
Learning Circuits

AbstractAssociative learning, a critical learning principle to improve an individual’s adaptability, has been emulated by few organic electrochemical devices. However, complicated bias schemes, high write voltages, as well as process irreversibility hinder the further development of associative learning circuits. Here, by adopting a poly(3,4-ethylenedioxythiophene):tosylate/Polytetrahydrofuran composite as the active channel, we present a non-volatile organic electrochemical transistor that shows a write bias less than 0.8 V and retention time longer than 200 min without decoupling the write and read operations. By incorporating a pressure sensor and a photoresistor, a neuromorphic circuit is demonstrated with the ability to associate two physical inputs (light and pressure) instead of normally demonstrated electrical inputs in other associative learning circuits. To unravel the non-volatility of this material, ultraviolet-visible-near-infrared spectroscopy, X-ray photoelectron spectroscopy and grazing-incidence wide-angle X-ray scattering are used to characterize the oxidation level variation, compositional change, and the structural modulation of the poly(3,4-ethylenedioxythiophene):tosylate/Polytetrahydrofuran films in various conductance states. The implementation of the associative learning circuit as well as the understanding of the non-volatile material represent critical advances for organic electrochemical devices in neuromorphic applications.

scholarly journals Surface Stoichiometry and Depth Profile of Tix-CuyNz Thin Films Deposited by Magnetron Sputtering

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3191
Author(s):  
Arun Kumar Mukhopadhyay ◽  
Avishek Roy ◽  
Gourab Bhattacharjee ◽  
Sadhan Chandra Das ◽  
Abhijit Majumdar ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Photoelectron Spectroscopy ◽  
Film Surface ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relative Composition ◽  
Transmission Electron ◽  
Deposited Film ◽  
Deposited Films

We report the surface stoichiometry of Tix-CuyNz thin film as a function of film depth. Films are deposited by high power impulse (HiPIMS) and DC magnetron sputtering (DCMS). The composition of Ti, Cu, and N in the deposited film is investigated by X-ray photoelectron spectroscopy (XPS). At a larger depth, the relative composition of Cu and Ti in the film is increased compared to the surface. The amount of adventitious carbon which is present on the film surface strongly decreases with film depth. Deposited films also contain a significant amount of oxygen whose origin is not fully clear. Grazing incidence X-ray diffraction (GIXD) shows a Cu3N phase on the surface, while transmission electron microscopy (TEM) indicates a polycrystalline structure and the presence of a Ti3CuN phase.

EPITAXY OF ULTRATHIN CoO FILMS STUDIED BY XPD AND GIXRD

2002 ◽  
Vol 09 (02) ◽  
pp. 937-941 ◽  
Author(s):  
P. LUCHES ◽  
C. GIOVANARDI ◽  
T. MOIA ◽  
S. VALERI ◽  
F. BRUNO ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Lattice Constant ◽  
Photoelectron Spectroscopy ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
Direction Parallel ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Rocksalt Structure ◽  
Plane Lattice

CoO layers have been grown by exposing to oxygen the (001) body-centered-tetragonal (bct) surface of a Co ultrathin film epitaxially grown on Fe(001). Different oxide thicknesses in the 2–15 ML range have been investigated by means of synchrotron-radiation-based techniques. X-ray photoelectron spectroscopy has been used to check the formation of the oxide films; X ray photoelectron diffraction has given information concerning the symmetry of their unit cell; grazing incidence X-ray diffraction has allowed to evaluate precisely their in-plane lattice constant. The films show a CoO(001) rocksalt structure, rotated by 45° with respect to the bct Co substrate, with the [100] direction parallel to the substrate [110] direction. Their in-plane lattice constant increases as a function of thickness, to release the in-plane strain due to the 3% mismatch between the bulk CoO phase and the underlying substrate.

scholarly journals Structure-Dependent Mechanical Properties of ALD-Grown Nanocrystalline BiFeO3Multiferroics

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Anna Majtyka ◽  
Anna Nowak ◽  
Benoît Marchand ◽  
Dariusz Chrobak ◽  
Mikko Ritala ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Present Report ◽  
Structural Evolution ◽  
Atomic Layer ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Deposition ◽  
Pertinent Information

The present paper pertains to mechanical properties and structure of nanocrystalline multiferroic BeFiO3(BFO) thin films, grown by atomic layer deposition (ALD) on the Si/SiO2/Pt substrate. The usage of sharp-tip-nanoindentation and multiple techniques of structure examination, namely, grazing incidence X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectrometry, enabled us to detect changes in elastic properties(95 GPa≤E≤118 GPa)and hardness(4.50 GPa≤H≤7.96 GPa)of BFO after stages of annealing and observe their relation to the material’s structural evolution. Our experiments point towards an increase in structural homogeneity of the samples annealed for a longer time. To our best knowledge, the present report constitutes the first disclosure of nanoindentation mechanical characteristics of ALD-fabricated BeFiO3, providing a new insight into the phenomena that accompany structure formation and development of nanocrystalline multiferroics. We believe that our systematic characterization of the BFO layers carried out at consecutive stages of their deposition provides pertinent information which is needed to control and optimize its ALD fabrication.

scholarly journals Microstructure and Mechanical Properties of Ti + N Ion Implanted Cronidur30 Steel

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 427 ◽  
Author(s):  
Jie Jin ◽  
Wei Wang ◽  
Xinchun Chen
Keyword(s):  
Mechanical Properties ◽  
Ion Implantation ◽  
Photoelectron Spectroscopy ◽  
Structural Modification ◽  
Surface Region ◽  
Grazing Incidence ◽  
Bearing Steel ◽  
Near Surface ◽  
X Ray ◽  
Ion Implanted

In this study, Ti + N ion implantation was used as a surface modification method for surface hardening and friction-reducing properties of Cronidur30 bearing steel. The structural modification and newly-formed ceramic phases induced by the ion implantation processes were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and grazing incidence X-ray diffraction (GIXRD). The mechanical properties of the samples were tested by nanoindentation and friction experiments. The surface nanohardness was also improved significantly, changing from ~10.5 GPa (pristine substrate) to ~14.2 GPa (Ti + N implanted sample). The friction coefficient of Ti + N ion implanted samples was greatly reduced before failure, which is less than one third of pristine samples. Furthermore, the TEM analyses confirmed a trilamellar structure at the near-surface region, in which amorphous/ceramic nanocrystalline phases were embedded into the implanted layers. The combined structural modification and hardening ceramic phases played a crucial role in improving surface properties, and the variations in these two factors determined the differences in the mechanical properties of the samples.

GIAXD and XPS Characterization of sp3C Doped SiC Superhard Nanocomposite Film

2012 ◽  
Vol 512-515 ◽  
pp. 971-974
Author(s):  
Jian Yi ◽  
Xiao Dong He ◽  
Yue Sun ◽  
Zhi Peng Xie ◽  
Wei Jiang Xue ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Physical Vapor Deposition ◽  
Grazing Incidence ◽  
Nanocomposite Films ◽  
Second Phase ◽  
X Ray ◽  
Xps Characterization ◽  
Ss Substrates ◽  
Sic Film

The sp3C doped SiC superhard nanocomposite films had been deposited on stainless steel (SS) substrates at different temperature by electron beam-physical vapor deposition (EB-PVD). The sp3C doped SiC film was studied by grazing incidence X-ray asymmetry diffraction (GIAXD), and X-ray photoelectron spectroscopy (XPS). The results of GIAXD showed that the sp3 doped SiC nanocomposite films were not perfect crystalline, which was composed with fine SiC nanocrystals, and a second phase very similar with diamond like carbon (DLC). XPS analysis showed that the excess C existing in films and turned from diamond into DLC from the surface to inner of film.

scholarly journals Origin of surface impurities on the Cave of Swords selenite crystals at Naica

2014 ◽  
Vol 70 (a1) ◽  
pp. C66-C66
Author(s):  
Maria Elena Montero-Cabrera ◽  
Isai Castillo-Sandoval ◽  
Luis Fuentes-Cobas ◽  
Hilda Esparza-Ponce ◽  
Maria Elena Fuentes-Montero ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Grazing Incidence ◽  
Confocal Laser ◽  
Heterogeneous Distribution ◽  
Edge Structure ◽  
X Ray ◽  
Transmission Electron ◽  
Incidence Geometries ◽  
The Look

The Cave of Swords was discovered in 1910 at Naica mine, Chihuahua, Mexico. Its name refers to the look of the 1-2 m long crystals the cave had when it was discovered. Currently the crystals are 0.1-0.3 m long. The crystals surface is opaque and ocher. For over 100 years these crystals continue to amaze and give us clues about their formation. This work is part of a research aimed at the conservation of the Naica Giant Crystals. Thirteen samples from the Cave of Swords were analyzed by Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Confocal Laser Microscopy with Differential Interference Contrast (LCM-DIM) and Transmission Electron Microscopy (TEM). X-Ray Fluorescence (μ-XRF) together with X-ray Absorption Near Edge Structure (μ-XANES) and X-ray Photoelectron Spectroscopy (XPS) were employed for elemental analysis. For phase analysis, X-ray diffraction (XRD) in both symmetric and grazing incidence geometries (GI-XRD) and Micro electron diffraction at TEM were used. Impurities on crystals surfaces show a heterogeneous distribution of the present elements. The thickness of impurities ranges from 120 nm to 150 μm. The phases identified were (see figure) gypsum (1, 2, 3, 6, 9, 10, 13), hematite (4, 7, 8), sphalerite (14), chalcopyrite (11), cuprite (15), galena (5), alabandite (12), halite, fluorite and amorphous Pb and Mn oxy-hydroxides. Al, C, Ca, Cl, Cu, F, Fe, Mg, Mn, Na, O, Pb, S, Si and Zn elements were identified. A model for the origin of impurities follows: Selenite stopped growing when the solution became sub-saturated. Then, hematite was deposited as the main phase, which was dissolved or suspended in the solution. Hematite matrix served for the adsorption of other crystalline and amorphous phases. We concluded that humans have not produced the impurities, which are witnesses of the gypsum crystals formation. Acknowledgment: Stanford Synchrotron Radiation Lightsource, Harvard Museum of Natural History and CONACYT CB-183706.

scholarly journals Hydroxyapatite Formation on a Novel Dental Cement in Human Saliva

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Johanna Engstrand ◽  
Erik Unosson ◽  
Håkan Engqvist
Keyword(s):  
Photoelectron Spectroscopy ◽  
Dental Materials ◽  
Grazing Incidence ◽  
Human Saliva ◽  
Dental Cement ◽  
X Ray ◽  
Luting Cement ◽  
Natural Formation ◽  
High Standards ◽  
The Stability

Dental materials have to meet high standards regarding mechanical strength and handling properties. There is however only a limited amount of research that has been devoted to natural formation of hydroxyapatite (HA) in contact with the materials. The objective of the current investigation was to study the surface reactions occurring in human salvia on a novel dental cement. Ceramir Crown & Bridge, a bioceramic luting agent intended for permanent cementation of conventional oral prosthetics, was evaluated by immersing discs made from the cement in human saliva and phosphate buffered saline (PBS) for seven days, after which they were dried and analyzed. The analytical methods used in order to verify HA formation on the surface were grazing incidence X-ray diffraction (GI-XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All results showed that HA was formed on the surfaces of samples stored in saliva as well as on samples stored in PBS. The possibility of a dental luting cement to promote natural formation of HA at the tooth interface increases the stability and durability of the system and could help prevent secondary caries.

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