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The dc breakdown voltage value in points near the Paschen minimum for SF 6 gas has been analysed. The dc breakdown voltage and voltage V −4 (voltage at which pre-breakdown current equals 10 −4 A) were measured experimentally. Variable parameters in the experiment included pressure, inter-electrode distance and electrode material. The results obtained by the experiment were...
We present an approach for distillation of the coordination-resolved electronic binding energy and bond relaxation dynamics, which has enabled clarification of the catalytic nature of under- and hetero-coordinated atoms. It is classified that Pt adatoms and CuPd alloy serve as acceptor-type catalysts because of the bond-order-deficiency induced quantum entrapment while Rh adatoms and AgPd alloy serve...
Samples of silicon carbide were exposed to carbon dioxide plasma at high temperature to study thermal and chemical degradation, as well as the evolution of surface morphology. Scanning electron microscope images revealed that the samples remained fairly intact up to a temperature of approximately 1700 K, when surface modification and degradation started to occur. The oxidation at high temperature...
In this study we report on the micro-, and nanostructural, morphological and electrical properties of Ti(20 nm)/Cr(120 nm)/Al(50 nm) contacts to n-GaN by electron microscopy, X-ray diffraction and I–V measurements. Tested contacts were annealed at the temperature of 400, 700 and 900 °C for 10 min in vacuum. It was found that Cr appeared in the top part of the GaN epitaxial layer at 700 °C. High resolution...
An approach to model a transient flow of rarefied gas through a long capillary based on numerical data for flow rate previously obtained from the linearized and stationary kinetic equation was proposed. As an example, non-steady flow through a long circular tube connecting two reservoirs is considered. Pressures in the reservoirs and flow rates in the inlet and outlet are obtained as a function of...
The ternary Ti–Zr–V non-evaporable getter coating is widely used on accelerator vacuum chambers in many accelerator centres. This coating can be activated at 180 °C for 24 h and has well repeatable pumping characteristics. A new quaternary Ti–Zr–Hf–V coating was deposited onto inner surface of stainless steel tubular samples. This coating can be activated at lower temperature of 150–160 °C for 24 h and...
Cathodic arc-evaporation is a standard deposition technique to synthesize high quality coatings. However, this technique indicates to be very sensitive when preparing oxide films. It has been shown that the synthesis of (Al 0.7 Cr 0.3 ) 2 O 3 coatings utilizing Al–Cr composite targets was accompanied by the formation of Al-rich oxide islands formed at the target surface...
Ternary alloys of composition close to Cr 2 AlC have been deposited by ion beam sputtering onto unheated and heated to 380 °C Si substrates. As-deposited films are amorphous. Annealing of the film in vacuum at 700 °C leads to crystallisation with 39.2 nm crystallites. Crystallisation also can be achieved by annealing in air but there is also partial oxidation of the film surface to the depth...
Sputtering and secondary ion emission (SIE) from semiconductors with different values of the band gap have been studied experimentally and by means of computer simulation. The particular oscillations of secondary ion energy distribution for graphite, sapphire, and silicon single crystals were observed under irradiation by 1 and 10 keV Ar + ions. This result cannot be interpreted using existing...
A brief history of the journal Vacuum is given covering its launch in 1951 as volume 1 of an in-house journal of Edwards High Vacuum Ltd to its present 100th volume, now as an Elsevier journal.
Optical transmittance spectra of wurtzite AlN film deposited on Al 2 O 3 (0001) substrate by pulsed laser deposition (PLD) technique with a two-step pressure process were studied in the temperature range of 77–450 K. The bandgap and characteristic Urbach's parameters were determined using a detailed procedure developed for analyzing the transmittance spectra. The temperature dependence...
Multiwalled carbon nanotubes-TiO 2 (MWCNTs–TiO 2 ) composite thin films were deposited on glass substrates by the sol–gel spin coating technique and doped with nitrogen ions using ion-implantation. The dose of implanted N + was chosen as 3 × 10 15 and 1 × 10 16 ions/cm 2 , respectively. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray...
Up to now, it was believed, that the deterioration of vacuum insulation panels (VIP) thermal properties is primarily due dry gas and moisture permeation through its barrier envelope. The increase in internal pressure and the absorption of water on the large internal surface of the porous silica core deteriorates the thermal performance by inducing an increase in the thermal conductivity. Based on...
To explore the future application of diamond films coated by hot-filament chemical vapour deposition on tungsten carbide for lunar exploration, a comparative study of tribological behaviour of the film sliding in air and in vacuum under four different temperatures was conducted. Results showed that the coefficient of friction (COF) in air basically decreased with elevated temperature and, in vacuum,...
We present an experimental characterization of a new vacuum gauge based on a K type micro thermocouple with 25.4 μm diameter. This sensor is intended for the simultaneous measurement of the temperature and pressure in the ranges extending from 293 K to 400 K and 10 −1 Pa to 10 5 Pa respectively. The paper gives an investigation of the micro-thermocouple vacuum gauge signal for the...
The present work is aimed at developing gold nanostructures functionalized with antenna systems to exploit the synergistic nanostructure/antenna desorption-ionization efficiency. A potential Matrix-Assisted Laser Desorption Ionisation (MALDI) organic matrix has been modified introducing specific functional groups or molecular linker and used as a capping agent for gold nanostructures.In particular,...
Vacuum gauges that control fast processes in industrial applications, e.g. load locks, should immediately react to pressure changes. To study the response time of vacuum gauges to rapid pressure changes, a dynamic vacuum standard was developed where the pressure may change from 100 kPa to 100 Pa within 20 ms in a step-wise manner or within longer times up to 1 s in a predictable manner. This is accomplished...
A method for synthesis of large quantities of iron oxide nanowires using low purity substrates is presented. One cm thick commercially available iron plates of purity 98 at.% were supplied from a steel company. The plates prepared by hot rolling contained several μm thick surface oxide films formed during industrial processing. Plates were cut to small samples and exposed to highly dissociated oxygen...
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