scholarly journals The Gas-atmosphere Effect on the Electrical Conductivity of Ultra-thin Pt films.

Shinku ◽  
1998 ◽  
Vol 41 (3) ◽  
pp. 255-257
Author(s):  
Ayako HIOKI ◽  
Akio OKAMOTO ◽  
Kazuki NATSUKAWA ◽  
Soichi OGAWA
Keyword(s):  
Electrical Conductivity ◽  
Atmosphere Effect ◽  
Gas Atmosphere ◽  
Pt Films

Surface morphology and electrical property evolution of super-thin Pt film on 6H-SiC substrate during annealing

2011 ◽  
Vol 26 (3) ◽  
pp. 256-261
Author(s):  
Jingjing Yang ◽  
Wenxia Yuan ◽  
Xiaopeng Zeng
Keyword(s):  
Electrical Conductivity ◽  
Electrical Property ◽  
Surface Morphology ◽  
Thin Layer ◽  
Annealing Temperature ◽  
Composition Gradient ◽  
Mechanism Analysis ◽  
Pt Films ◽  
Low Solubility ◽  
Crystalline Graphite

We reported the surface morphology and electrical property of super-thin Pt films, ∼2 nm thick, deposited on 6H-SiC (0001) substrates and subsequently annealed from 400 to 1000 °C. The surfaces of the films were found to have a feature of islands growth, and the sizes of the islands increased with increasing annealing temperature. Free carbon, produced by selective reactions between Pt and SiC, diffused toward the top surface across the product layers due to low solubility and composition gradient of carbon throughout the reaction zone. A dramatic change of electrical conductivity of the films was observed. A mechanism analysis reveals that the origin came from the contribution of aggregation of islands on the surface and formation of Pt silicides and a thin layer of crystalline graphite.

(100) Oriented Platinum thin Films Deposited by Dc Magnetron Sputtering On SiO 2/Si Substrates

1996 ◽  
Vol 441 ◽  
Author(s):  
Dong-Yeon Park ◽  
Dong-Su Lee ◽  
Min Hong Kim ◽  
Tae-Soon Park ◽  
Hyun-Jung Woo ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Surface ◽  
Adhesion Test ◽  
Dc Magnetron Sputtering ◽  
Mixed Gas ◽  
Si Substrates ◽  
Gas Atmosphere ◽  
Sputter Deposited ◽  
Pt Films ◽  
Deposition Conditions

AbstractPlatinum(Pt) films were sputter-deposited on Si02/Si substrates under the mixed gas atmosphere of Ar and O2. Under certain deposition conditions, the films were oriented such that the (100) direction is normal to the substrate surface. The formation of the (100) texture was affected by the gas pressure and film thickness. After annealing at 650 °C for 1 hour, (100) oriented Pt films with the resistivity of pure Pt were obtained. The annealed Pt films all passed a tape adhesion test and had no defects such as hillocks or pinholes. The experimental results from this work are presented.

Comparison of PtSi Films Grown by Solid-State Reaction and by E-Beam Co-Evaporation: Thermal Stability in Air at 1000 °C

MRS Advances ◽  
2016 ◽  
Vol 1 (21) ◽  
pp. 1539-1544
Author(s):  
Robert T. Fryer ◽  
Robert J. Lad
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Solid State Reaction ◽  
Grain Morphology ◽  
X Ray Diffraction ◽  
Columnar Grain ◽  
Pt Films ◽  
Granular Morphology ◽  
Oxidation Mechanisms

ABSTRACTTwo different methods were used to synthesize 200 nm thick single-phase, orthorhombic-PtSi films: (i) e-beam co-evaporation (EBC) of Pt and Si onto r-sapphire substrates and (ii) solid-state reaction (SSR) of sputtered Pt films on Si (100) wafers. Morphology, electrical conductivity, and crystalline structure were characterized for as-grown films and for films annealed in air at 1000 °C via scanning electron microscopy (SEM), 4-pt conductivity measurements, andin situX-ray diffraction (XRD). As-grown EBC films exhibit columnar grain morphology and slight (101) crystalline texture, while SSR films exhibit granular morphology with many voids and a strong (002) texture. Above 600 °C, EBC PtSi films rapidly oxidize to form crystalline Pt3Si and amorphous SiO2phases. Around 1000 °C, the Pt3Si phase melts and c-Pt grains nucleate. After air annealing for 6 h at 1000 °C, room-temperature XRD shows that the oxidized EBC films consist of Pt3Si and Pt phases within a SiO2matrix and become electrically insulating. SSR films initially form with a (002) o-PtSi orientation and above 900 °C they recrystallize to preferred (101) texture and exhibit an unchanged electrical conductivity and a stable film morphology during 48 h of air annealing at 1000 °C. Separate oxidation mechanisms are proposed for the two film types.

Investigation of Electrical Hydrogen Detection Properties of Pt/WO3 Thin Films Prepared by Sol-Gel Method

2011 ◽  
Vol 485 ◽  
pp. 271-274 ◽  
Author(s):  
Yuki Yamaguchi ◽  
Tohru Kineri ◽  
Masakatsu Fujimoto ◽  
Hideo Mae ◽  
Atsuo Yasumori ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Tungsten Trioxide ◽  
Sol Gel ◽  
Optical And Electrical Properties ◽  
Pt Nanoparticle ◽  
Gas Concentration ◽  
Gas Atmosphere ◽  
Sol Gel Process ◽  
Sensor Devices

Platinum (Pt)nanoparticle-dispersed tungsten trioxide (WO3) thin film is a gasochromic material that changes color from transparent to blue in an H2 gas atmosphere. The electrical conductivity of Pt-nanoparticle-dispersed WO3 is dependent on inserted protons and electrons, though the material is insulator in air, because these electrons and protons work as electrical carriers in WO3. In this study, Pt-nanoparticle-dispersed WO3 thin films were prepared using the sol-gel process, and the optical and electrical properties were evaluated in an atmosphere with or without H2 gas. Pt/WO3 thin films prepared at 400°C showed the largest change in electrical conductivity when exposed to 1% H2 gas compared with thin films prepared at other temperatures. The electrical conductivity of the film was dependent on an H2 gas concentration in the range from 100 ppm to 1%. Pt/WO3 thin films prepared by the sol-gel process are expected to be used for H2 gas sensor devices due to the linear relationship between the electrical conductivity and H2 gas concentration.

scholarly journals Samples of Ba1−xSrxCe0.9Y0.1O3−δ, 0 < x < 0.1, with Improved Chemical Stability in CO2-H2 Gas-Involving Atmospheres as Potential Electrolytes for a Proton Ceramic Fuel Cell

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1874
Author(s):  
Magdalena Dudek ◽  
Bartłomiej Lis ◽  
Radosław Lach ◽  
Salius Daugėla ◽  
Tomas Šalkus ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Grain Boundary ◽  
Chemical Stability ◽  
Chemical Resistance ◽  
Hydrogen Gas ◽  
Boundary Conductivity ◽  
Co2 Gas ◽  
Gas Atmosphere ◽  
Ceramic Fuel ◽  
Ceramic Fuel Cells

Comparative studies were performed on variations in the ABO3 perovskite structure, chemical stability in a CO2-H2 gas atmosphere, and electrical conductivity measurements in air, hydrogen, and humidity-involving gas atmospheres of monophase orthorhombic Ba1−xSrxCe0.9Y0.1O3−δ samples, where 0 < x < 0.1. The substitution of strontium with barium resulting in Ba1−xSrxCe0.9Y0.1O3−δ led to an increase in the specific free volume and global instability index when compared to BaCe0.9Y0.1O3−δ. Reductions in the tolerance factor and cell volume were found with increases in the value of x in Ba1−xSrxCe0.9Y0.1O3−δ. Based on the thermogravimetric studies performed for Ba1−xSrxCe0.9Y0.1O3−δ, where 0 < x < 0.1, it was found that modified samples of this type exhibited superior chemical resistance in a CO2 gas atmosphere when compared to BaCe0.9Y0.1O3−δ. The application of broadband impedance spectroscopy enabled the determination of the bulk and grain boundary conductivity of Ba1−xSrxCe0.9Y0.1O3−δ samples within the temperature range 25–730 °C. It was found that Ba0.98Sr0.02Ce0.9Y0.1O3−δ exhibited a slightly higher grain interior and grain boundary conductivity when compared to BaCe0.9Y0.1O3−δ. The Ba0.95Sr0.05Ce0.9Y0.1O3−δ sample also exhibited improved electrical conductivity in hydrogen gas atmospheres or atmospheres involving humidity. The greater chemical resistance of Ba1−xSrxCe0.9Y0.1O3−δ, where x = 0.02 or 0.05, in a CO2 gas atmosphere is desirable for application in proton ceramic fuel cells supplied by rich hydrogen processing gases.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

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