scholarly journals Granular metal–carbon nanocomposites as piezoresistive sensor films – Part 1: Experimental results and morphology

2018 ◽  
Vol 7 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Günter Schultes ◽  
Hanna Schmid-Engel ◽  
Silvan Schwebke ◽  
Ulf Werner
Keyword(s):  
Metal Concentration ◽  
Plasma Deposition ◽  
Thermal Coefficient ◽  
Strain Sensitivity ◽  
Carbon Phase ◽  
Piezoresistive Sensor ◽  
Transmission Electron ◽  
Deposition Processes ◽  
Two Phases ◽  
Thermal Coefficient Of Resistance

Abstract. We have produced granular films based on carbon and different transition metals by means of plasma deposition processes. Some of the films possess an increased strain sensitivity compared to metallic films. They respond to strain almost linearly with gauge factors of up to 30 if strained longitudinally, while in the transverse direction about half of the effect is still measured. In addition, the film's thermal coefficient of resistance is adjustable by the metal concentration. The influence of metal concentration was investigated for the elements Ni, Pd, Fe, Pt, W, and Cr, while the elements Co, Au, Ag, Al, Ti, and Cu were studied briefly. Only Ni and Pd have a pronounced strain sensitivity at 55 ± 5 at. % (atomic percent) of metal, among which Ni–C is far more stable. Two phases are identified by transmission electron microscopy and X-ray diffraction: metal-containing nanocolumns densely packed in a surrounding carbon phase. We differentiate three groups of metals, due to their respective affinity to carbon. It turns out that only nickel has the capability to bond and form a stable and closed encapsulation of GLC around each nanoparticle. In this structure, the electron transport is in part accomplished by tunneling processes across the basal planes of the graphitic encapsulation. Hence, we hold these tunneling processes responsible for the increased gauge factors of Ni–C composites. The other elements are unable to form graphitic encapsulations and thus do not exhibit elevated gauge factors.

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

scholarly journals Photocatalytic activity of Cu2O/ZnO nanocomposite for the decomposition of methyl orange under visible light irradiation

2019 ◽  
Vol 26 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Xian-sheng Wang ◽  
Yu-duo Zhang ◽  
Qiao-chu Wang ◽  
Bo Dong ◽  
Yan-jia Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Methyl Orange ◽  
Photoelectron Spectroscopy ◽  
Visible Region ◽  
Methyl Orange Solution ◽  
Degradation Efficiency ◽  
X Ray ◽  
Transmission Electron ◽  
Consistent Performance ◽  
Two Phases

AbstractZnO is modified by Cu2O by the process of precipitation and calcination. X-ray diffraction has shown that Cu2O/ZnO catalysts are made of highly purified cubic Cu2O and hexagonal ZnO. Scanning electron microscopy and transmission electron microscopy have shown that ZnO adhered to the surface of Cu2O. Due to the doping of Cu2O, the absorption range of the Cu2O/ZnO catalyst is shifted from the ultraviolet to the visible region due to diffuse reflection. X-ray photoelectron spectroscopy and photoluminescence spectra have confirmed that there is a substantial interaction between the two phases of the resultant catalyst. The degradation efficiency of Cu2O/ZnO on methyl orange solution is obviously enhanced compared to Cu2O and ZnO. The maximum degradation efficiency is 98%. The degradation efficiency is affected by the pH of the solution and initial concentration. After three rounds of recycling, the degradation rate is almost same. This shows a consistent performance of Cu2O/ZnO. The increase in catalytic ability is related to the lattice interaction caused by the doping of Cu2O.

scholarly journals Deposition of Dielectric Optical Coatings: A Microstructural Study of the Deposited Layers and Interfaces

1989 ◽  
Vol 152 ◽  
Author(s):  
J. M. McCarthy ◽  
L. E. Thomas ◽  
W. T. Pawlewicz ◽  
W. S. Frydrych ◽  
G. J. Exarhos
Keyword(s):  
Plasma Deposition ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Dielectric Films ◽  
Optical Coatings ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
Optical Applications ◽  
Thin Dielectric Films ◽  
Deposition Techniques

ABSTRACTThin dielectric films for optical applications are deposited on substrates using a variety of techniques including reactive sputtering, solgel reaction, and ion assisted plasma deposition. This transmission electron microscopy study characterizes optical coatings produced by the above deposition techniques and shows how changes in deposition conditions change microstructure and as a result the optical properties.

scholarly journals Structural characterization of Yba2Cu3O7–δ/Y2O3 composite films

1998 ◽  
Vol 13 (4) ◽  
pp. 954-958 ◽  
Author(s):  
P. R. Broussard ◽  
M. A. Wall ◽  
J. Talvacchio
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Coincidence Site Lattice ◽  
Composite Films ◽  
X Ray Diffraction ◽  
Plane Orientation ◽  
Transmission Electron ◽  
Two Phases ◽  
High Degree

Using 4-circle x-ray diffraction and transmission electron microscopy, we have studied the microstructure and in-plane orientation of the phases present in thin film composite mixtures of Yba2Cu3O7–δ and Y2O3. We see a high degree of in-plane orientation and have verified a previous prediction for the in-plane order of Y2BaCuO5 on (110) MgO. Transmission electron microscopy shows the composite films to be a mixture of two phases, with YBCO grain sizes of ≈1 μm. We have also compared our observations of the in-plane order to the predictions of a modified near coincidence site lattice model.

scholarly journals On the preparation and properties investigations of highly performant MXene (Ti3C2(OH)2) nanosheets-reinforced phthalonitrile nanocomposites

2019 ◽  
Vol 28 ◽  
pp. 2633366X1989062 ◽  
Author(s):  
Mehdi Derradji ◽  
Djalal Trache ◽  
Abdelkhalek Henniche ◽  
Abdeljalil Zegaoui ◽  
Aboubakr Medjahed ◽  
...  
Keyword(s):  
Polymer Composites ◽  
High Performance ◽  
Electron Microscopies ◽  
Morphological Studies ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Transmission Electron ◽  
High Performance Polymer ◽  
Two Phases ◽  
New Generation

Taking into consideration the latest advances in both ceramic and polymer fields, a new generation of high-performance polymer composites based on the state-of-the-art MXene (Ti3C2(OH)2) ceramics and one of the leading high-performance thermosets, namely the phthalonitrile resins, is presented. The synergistic combination between the two phases led to nanocomposites exhibiting an outstanding thermal stability with starting decomposition temperatures not less than 484°C for 3 wt% of nanoloading. The tensile properties were as high as those obtained with fiber-reinforced polymer composites. For instance, the tensile strength reached its highest value of 276 MPa for the maximum loading of 3 wt%. The morphological studies carried out by scanning and transmission electron microscopies corroborated the improvements of the thermal and mechanical properties. Undoubtfully, such materials expected to be used in extreme conditions can be seen as the next generation of ceramics-reinforced polymer composites.

Orientation Relationships in the System Nb-NbCr2

1997 ◽  
Vol 3 (S2) ◽  
pp. 707-708
Author(s):  
P. G. Kotula ◽  
K. C. Chen ◽  
D. J. Thoma ◽  
F. Chu ◽  
T. E. Mitchell
Keyword(s):  
Microstructural Characterization ◽  
Laves Phase ◽  
Orientation Relationships ◽  
Ion Milling ◽  
Two Phase ◽  
Laves Phases ◽  
Arc Melting ◽  
Transmission Electron ◽  
Structural Applications ◽  
Two Phases

Laves-phase intermetallics are of potential use as high-temperature structural materials. NbCr2-based C15-structured alloys are of particular interest for such applications. by themselves, Laves phases generally have poor ductility and fracture toughness at low temperatures. Two phase alloys (i.e., Laves phase and the ductile bcc phase) are considered more promising for structural applications. The orientation relationships between the two phases can contribute to the mechanical behavior of the material. In this study, observations of two different orientation relationships in a Nb-NbCr2 eutectic are discussed and compared with previous studies of the NbCr2 system, as well as the TiCr2 system.A Nb-NbCr2 eutectic alloy was prepared by arc-melting high-purity alloys followed by annealing at 1400°C for 100 h and then cooling at l°C/min. The complete details of the materials preparation have been given elsewhere. Specimens were prepared for observation in the transmission electron microscope (TEM) by cutting 3 mm discs with a coring saw, followed by dimpling and ion milling. Microstructural characterization was performed with a Philips CM30 TEM operating at 300 kV.

scholarly journals Vertically Aligned Few-Layered Graphene-Based Non-Cryogenic Bolometer

2019 ◽  
Vol 5 (2) ◽  
pp. 23 ◽  
Author(s):  
Anil K. Yadav ◽  
Saba Mehsar Khan ◽  
Anirban Kundu ◽  
Renu Rani ◽  
Navneet Soin ◽  
...  
Keyword(s):  
Room Temperature ◽  
Thermal Coefficient ◽  
Carbon Nanomaterial ◽  
Electrical Switching ◽  
Current Voltage ◽  
Infra Red ◽  
Vertically Aligned ◽  
Thermal Coefficient Of Resistance ◽  
Probe Measurements ◽  
Bolometric Effect

In this study, we report the photoresponse of vertically aligned few-layered graphene (VAG) upon infra-red (IR) irradiation at room temperature. Four probe measurements showed the current–voltage (I–V) characteristic of electrical switching during pulsed IR irradiation. The photoresponse reported here for VAG was significantly higher than that reported for carbon nanotube (CNT) samples. Our investigation shows that such a photoresponse arose solely from the bolometric effect, where the conductivity changed with temperature. The resistance magnitude of the VAGs increased ~two fold for each 6 °C increase in temperature. Also, the Thermal Coefficient of Resistance (TCR) in this region was ~11%/K, which is the highest TCR value reported for any carbon nanomaterial.

scholarly journals Rapid identification of capsulated Acinetobacter baumannii using a density-dependent gradient test

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Hadas Kon ◽  
David Schwartz ◽  
Elizabeth Temkin ◽  
Yehuda Carmeli ◽  
Jonathan Lellouche
Keyword(s):  
Rapid Identification ◽  
Control Measures ◽  
Clinical Severity ◽  
Bottom Phase ◽  
Gram Negative ◽  
Density Dependent ◽  
Infection Control Measures ◽  
Transmission Electron ◽  
Total Carbohydrates ◽  
Two Phases

Abstract Background Gram-negative bacterial capsules are associated with production of carbohydrates, frequently resulting in a mucoid phenotype. Infections caused by capsulated or mucoid A. baumannii are associated with increased clinical severity. Therefore, it is clinically and epidemiologically important to identify capsulated A. baumannii. Here, we describe a density-dependent gradient test to distinguish between capsulated and thin/non-capsulated A. baumannii. Results Thirty-one of 57 A. baumannii isolates displayed a mucoid phenotype. The density-dependent gradient test was comprised of two phases, with silica concentrations of 30% (top phase) and 50% (bottom phase). Twenty-three isolates migrated to the bottom phase, indicating thin or non-capsulated strains, and 34 migrated to the top phase, suggesting strains suspected to be capsulated. There was agreement between the mucoid and the non-mucoid phenotypes and the density-dependent gradient test for all but three isolates. Total carbohydrates extracted from strains suspected to be capsulated were significantly higher. Transmission electron microscopy confirmed the presence of a capsule in the six representative strains suspected to be capsulated. Conclusions The density-dependent gradient test can be used to verify capsule presence in mucoid-appearing A. baumannii strains. Identifying capsulated strains can be useful for directing infection control measures to reduce the spread of hypervirulent strains.

Structure of Frilled Carbon Nanowires Synthesized by Sulfur-assisted Chemical Vapor Deposition

2001 ◽  
Vol 706 ◽  
Author(s):  
Tadashi Mitsui ◽  
Takashi Sekiguchi ◽  
Mikka Nishitani-Gamo ◽  
Yafei Zhang ◽  
Toshihiro Ando
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
Carbon Phase ◽  
Transmission Electron ◽  
Diamond Substrate ◽  
Thin Film Catalyst ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

AbstractEffects of hydrogen sulfide on the structure of carbon nanotubes (CNTs) were studied using high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). The CNTs were synthesized with an iron thin-film catalyst by microwave plasma-assisted CVD on the diamond substrate. The HRTEM images revealed that essentially all of the CNTs obtained in this study were multiwall (MWCNT). The addition of H2S resulted in nanotubes with split skins as cornhusks and/or frills. Electron energy loss spectra of the cornhusks indicated that they consist of sp2, sp3 and amorphous carbon phase. The spectra revealed that the sp3 to sp2 ratio at the points where cornhusks divide from the main stem was more than that at the edge of the cornhusks. No evidence of sulfur incorporation into the MWCNTs grown with the H2S addition was found. We speculate that the chemical nature of sulfur on the CNT growth yields such anomalous structure.

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