Moduli vacuum bubbles produced by evaporating black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, J. R.

2007-10-15

We consider a model with a toroidally compactified extra dimension giving rise to a temperature-dependent 4D effective potential with one-loop contributions due to the Casimir effect, along with a 5D cosmological constant. The forms of the effective potential at low and high temperatures indicate a possibility for the formation of a domain wall bubble, formed by the modulus scalar field, surrounding an evaporating black hole. This is viewed as an example of a recently proposed black hole vacuum bubble arising from matter-sourced moduli fields in the vicinity of an evaporating black hole [D. Green, E. Silverstein, and D. Starr, Phys.more » Rev. D 74, 024004 (2006)]. The black hole bubble can be highly opaque to lower-energy particles and photons, and thereby entrap them within. For high-temperature black holes, there may also be a symmetry-breaking black hole bubble of false vacuum of the type previously conjectured by Moss [I. G. Moss, Phys. Rev. D 32, 1333 (1985)], tending to reflect low-energy particles from its wall. A double bubble composed of these two different types of bubble may form around the black hole, altering the hole's emission spectrum that reaches outside observers. Smaller mass black holes that have already evaporated away could have left vacuum bubbles behind that contribute to the dark matter.« less

Miniaturized transportable evaporator for molecule deposition inside cryogenic scanning probe microscopes.

PubMed

Lämmle, K; Schwarz, A; Wiesendanger, R

2010-05-01

Here, we present a very small evaporator unit suitable to deposit molecules onto a sample in a cryogenic environment. It can be transported in an ultrahigh vacuum system and loaded into Omicron-type cantilever stages. Thus, molecule deposition inside a low temperature force microscope is possible. The design features an insulating base plate with two embedded electrical contacts and a crucible with low power consumption, which is thermally well isolated from the surrounding. The current is supplied via a removable power clip. Details of the manufacturing process as well as the used material are described. Finally, the performance of the whole setup is demonstrated.

Determining the virtual surface in the thermal evaporation process of magnesium fluoride from a tungsten boat for different deposition rates, to be used in precision optical components

NASA Astrophysics Data System (ADS)

Tejada Esteves, A.; Gálvez de la Puente, G.

2013-11-01

Vacuum thermal evaporation has, for some time now, been the principal method for the deposition of thin films, given, among other aspects, its simplicity, flexibility, and relatively low cost. Therefore, the development of models attempting to predict the deposition patterns of given thin film materials in different locations of a vacuum evaporation chamber are arguably important. With this in mind, we have designed one of such models for the thermal evaporation process of magnesium fluoride (MgF2), a common material used in optical thin films, originating from a tungsten boat source. For this we took several deposition samples in glass slide substrates at different locations in the vacuum chamber, considering as independent variables the mean deposition rate, and the axial and vertical distances of the source to the substrate. After a careful analysis by matrix method from the spectral transmittance data of the samples, while providing as output data the spectral transmittance, as well as the physical thickness of the films, both as functions of the aforementioned variables, the virtual surface of the source was determined.

A miniature single element effusion cell for the vacuum deposition of transition-metal and rare-earth elements

NASA Astrophysics Data System (ADS)

Harris, V. G.; Koon, N. C.

1997-08-01

A miniature single element effusion cell has been fabricated and tested that allows for the high-vacuum deposition of a variety of transition-metal and rare-earth elements. The cell is designed to operate under high-vacuum conditions, ≈10-9 Torr, with low power demands, <200 W. The virtues of this evaporator are the simplicity of design and ease of fabrication, assembly, maintenance, and operation.

Photoluminescence and anti-deliquesce of cesium iodide and its sodium-doped films deposited by thermal evaporation at high deposition rates

NASA Astrophysics Data System (ADS)

Hsu, Jin-Cherng; Chiang, Yueh-Sheng; Ma, Yu-Sheng

2013-03-01

Cesium iodide (CsI) and sodium iodide (NaI) are good scintillators due to their high luminescence efficiency. These alkali halides can be excited by ultra-violet or by ionizing radiation. In this study, CsI and its Na-doped films about 8 μm thick were deposited by thermal evaporation boat without heating substrates at high deposition rates of 30, 50, 70, 90, and 110 nm/sec, respectively. The as-deposited films were sequentially deposited a silicon dioxide film to protect from deliquesce. And, the films were also post-annealed in vacuum at 150, 200, 250, and 300 °C, respectively. We calculated the packing densities of the samples according to the measurements of Fourier transform infrared spectroscopy (FTIR) and observed the luminescence properties by photoluminescence (PL) system. The surfaces and cross sections of the films were investigated by scanning electron microscope (SEM). From the above measurements we can find the optimal deposition rate of 90 nm/sec and post-annealing temperature of 250 °C in vacuum for the asdeposited cesium iodide and its sodium-doped films.

Thermal deposition of intact tetrairon(III) single-molecule magnets in high-vacuum conditions.

PubMed

Margheriti, Ludovica; Mannini, Matteo; Sorace, Lorenzo; Gorini, Lapo; Gatteschi, Dante; Caneschi, Andrea; Chiappe, Daniele; Moroni, Riccardo; de Mongeot, Francesco Buatier; Cornia, Andrea; Piras, Federica M; Magnani, Agnese; Sessoli, Roberta

2009-06-01

A tetrairon(III) single-molecule magnet is deposited using a thermal evaporation technique in high vacuum. The chemical integrity is demonstrated by time-of-flight secondary ion mass spectrometry on a film deposited on Al foil, while superconducting quantum interference device magnetometry and alternating current susceptometry of a film deposited on a kapton substrate show magnetic properties identical to the pristine powder. High-frequency electron paramagnetic resonance spectra confirm the characteristic behavior for a system with S = 5 and a large Ising-type magnetic anisotropy. All these results indicate that the molecules are not damaged during the deposition procedure keeping intact the single-molecule magnet behavior.

Theoretical and experimental researches of the liquid evaporation during thermal vacuum influences

NASA Astrophysics Data System (ADS)

Trushlyakov, V.; Panichkin, A.; Prusova, O.; Zharikov, K.; Dron, M.

2018-01-01

The mathematical model of the evaporation process of model liquid with the free surface boundary conditions of the "mirror" type under thermal vacuum influence and the numerical estimates of the evaporation process parameters are developed. An experimental stand, comprising a vacuum chamber, an experimental model tank with a heating element is designed; the experimental data are obtained. A comparative analysis of numerical and experimental results showed their close match.

Numerical Study on Radiation Effects to Evaporator in Natural Vacuum Solar Desalination System

NASA Astrophysics Data System (ADS)

Siregar, R. E. T.; Ronowikarto, A. D.; Setyawan, E. Y.; Ambarita, H.

2018-01-01

The need for clean water is increasing day by day due to the increasing factor of living standard of mankind, hence designed natural vacuum solar desalination. The natural vacuum Solar desalination is studied experimentally. A small-scale natural vacuum desalination study consists of evaporator and condenser as the main components designed and manufactured. To transfer heat from the solar collector into the evaporator, the fluid transfer system uses a pump powered by a solar cell. Thus, solar collectors are called hybrid solar collectors. The main purpose of this exposure is to know the characteristics of the radiation effects on incoming energy on the evaporator during the process. This system is tested by exposing the unit to the solar radiation in the 4th floor building in Medan. The experiment was conducted from 8.00 to 16.00 local time. The results show that natural vacuum solar desalination with hybrid solar collectors can be operated perfectly. If the received radiation is high, then the incoming energy received by the evaporator will also be high. From measurements with HOBO microstation, obtained the highest radiation 695.6 W/m2, and the calculation result of incoming energy received evaporator obtained highest result 1807.293 W.

Construction and evaluation of an ultrahigh-vacuum-compatible sputter deposition source

NASA Astrophysics Data System (ADS)

Lackner, Peter; Choi, Joong Il Jake; Diebold, Ulrike; Schmid, Michael

2017-10-01

A sputter deposition source for the use in ultrahigh vacuum (UHV) is described, and some properties of the source are analyzed. The operating principle is based on the design developed by Mayr et al. [Rev. Sci. Instrum. 84, 094103 (2013)], where electrons emitted from a filament ionize argon gas and the Ar+ ions are accelerated to the target. In contrast to the original design, two grids are used to direct a large fraction of the Ar+ ions to the target, and the source has a housing cooled by liquid nitrogen to reduce contaminations. The source has been used for the deposition of zirconium, a material that is difficult to evaporate in standard UHV evaporators. At an Ar pressure of 9 ×1 0-6 mbar in the UHV chamber and moderate emission current, a highly reproducible deposition rate of ≈1 ML in 250 s was achieved at the substrate (at a distance of ≈50 mm from the target). Higher deposition rates are easily possible. X-ray photoelectron spectroscopy shows a high purity of the deposited films. Depending on the grid voltages, the substrate gets mildly sputtered by Ar+ ions; in addition, the substrate is also reached by electrons from the negatively biased sputter target.

Vacuum ultraviolet coatings of Al protected with MgF(2) prepared both by ion-beam sputtering and by evaporation.

PubMed

Fernández-Perea, Mónica; Larruquert, Juan I; Aznárez, José A; Pons, Alicia; Méndez, José A

2007-08-01

Ion-beam sputtering (IBS) and evaporation are the two deposition techniques that have been used to deposit coatings of Al protected with MgF(2) with high reflectance in the vacuum ultraviolet down to 115 nm. Evaporation deposited (ED) Al protected with IBS MgF(2) resulted in a larger (smaller) reflectance below (above) 125 nm than the well-known all-evaporated coatings. A similar comparison is obtained when the Al film is deposited by IBS instead of evaporation. The lower reflectance of the coatings protected with IBS versus ED MgF(2) above 125 nm is because of larger absorption of the former. Both nonprotected IBS Al, as well as IBS Al protected with ED MgF(2), resulted in a band of reflectance loss that was peaked at 127 and 157 nm, respectively. This result was attributed to the excitation of surface plasmons due to the enhancement of surface roughness with large spatial wave vectors in the sputter deposition. This reflectance loss for IBS Al protected with MgF(2) is small at the short (lambda~120 nm) and long (lambda<350 nm) wavelengths investigated. IBS Al protected with ED MgF(2) is thus a promising coating for these two spectral regions. Coatings protected with IBS MgF(2) resulted in a reflectance as high as coatings protected with ED MgF(2) at wavelengths longer than 550 nm, whereas the former had a lower reflectance below this wavelength.

Deposition of Methylammonium Lead Triiodide by Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

NASA Astrophysics Data System (ADS)

Barraza, E. Tomas; Dunlap-Shohl, Wiley A.; Mitzi, David B.; Stiff-Roberts, Adrienne D.

2018-02-01

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) was used to deposit the metal-halide perovskite (MHP) CH3NH3PbI3 (methylammonium lead triiodide, or MAPbI), creating phase-pure films. Given the moisture sensitivity of these crystalline, multi-component organic-inorganic hybrid materials, deposition of MAPbI by RIR-MAPLE required a departure from the use of water-based emulsions as deposition targets. Different chemistries were explored to create targets that properly dissolved MAPbI components, were stable under vacuum conditions, and enabled resonant laser energy absorption. Secondary phases and solvent contamination in the resulting films were studied through Fourier transform infrared (FTIR) absorbance and x-ray diffraction (XRD) measurements, suggesting that lingering excess methylammonium iodide (MAI) and low-vapor pressure solvents can distort the microstructure, creating crystalline and amorphous non-perovskite phases. Thermal annealing of films deposited by RIR-MAPLE allowed for excess solvent to be evaporated from films without degrading the MAPbI structure. Further, it was demonstrated that RIR-MAPLE does not require excess MAI to create stoichiometric films with optoelectronic properties, crystal structure, and film morphology comparable to films created using more established spin-coating methods for processing MHPs. This work marks the first time a MAPLE-related technique was used to deposit MHPs.

Source replenishment device for vacuum deposition

DOEpatents

Hill, Ronald A.

1988-01-01

A material source replenishment device for use with a vacuum deposition apparatus. The source replenishment device comprises an intermittent motion producing gear arrangement disposed within the vacuum deposition chamber. An elongated rod having one end operably connected to the gearing arrangement is provided with a multiarmed head at the opposite end disposed adjacent the heating element of the vacuum deposition apparatus. An inverted U-shaped source material element is releasably attached to the outer end of each arm member whereby said multiarmed head is moved to locate a first of said material elements above said heating element, whereupon said multiarmed head is lowered to engage said material element with the heating element and further lowered to release said material element on the heating element. After vaporization of said material element, second and subsequent material elements may be provided to the heating element without the need for opening the vacuum deposition apparatus to the atmosphere.

Source replenishment device for vacuum deposition

DOEpatents

Hill, R.A.

1986-05-15

A material source replenishment device for use with a vacuum deposition apparatus is described. The source replenishment device comprises an intermittent motion producing gear arrangement disposed within the vacuum deposition chamber. An elongated rod having one end operably connected to the gearing arrangement is provided with a multiarmed head at the opposite end disposed adjacent the heating element of the vacuum deposition apparatus. An inverted U-shaped source material element is releasably attached to the outer end of each arm member whereby said multiarmed head is moved to locate a first of said material elements above said heating element, whereupon said multiarmed head is lowered to engage said material element with the heating element and further lowered to release said material element on the heating element. After vaporization of said material element, second and subsequent material elements may be provided to the heating element without the need for opening the vacuum deposition apparatus to the atmosphere.

Oxygen Isotopic Fractionation During Evaporation of SiO2 in Vacuum and in H Gas

NASA Astrophysics Data System (ADS)

Nagahara, H.; Young, E. D.; Hoering, T. C.; Mysen, B. O.

1993-07-01

Chondritic components, chondrules, CAIs, and some parts of the matrix are believed to have formed and/or thermally processed in the solar nebula. If this scenario is the case, they should be fractionated for major and minor elements and isotopes according to the formation temperature. This is true for major and trace elements, but is not the case for isotopes. Differences in oxygen isotopic composition among meteorite groups are interpreted to be the results of mixing of gas and dust from different oxygen reservoirs, and the effect of isotopic fractionation is negligible for most meteorites except for rare CAIs. Davis et al. [1] studied the isotopic fractionation of SiO2, MgO, and forsterite and showed that oxygen isotopic fractionation from solid materials is very small, but that from liquid is significant. Evaporation in the solar nebula should, however, be in hydrogen gas, which is reactive with silicates. Therefore, the effect of hydrogen gas on the evaporation behaviors of silicates, including mode of evaporation, evaporation rate, and compositional and isotopic fractionation, should be studied. Nagahara [2] studied the evaporation rate of SiO2 in equilibrium, in constant evacuation (free evaporation), and in hydrogen, and showed that the rate in hydrogen gas is orders of magnitude larger than that in vacuum; the mode of evaporation also differs from that in vacuum. Oxygen isotopic fractionation during evaporation of SiO2 in constant evacuation and in hydrogen gas at two different total pressures are studied in the present study. The starting material is a single crystal of natural quartz, which should transform into high cristobalite at experimental conditions. The powdered starting material was kept in a graphite capsule without a cap and set in a vacuum chamber with and without hydrogen gas flow. Experimental temperature was 1600 degrees C. Oxygen isotopic compositions (^18O/^16O) were measured with the CO2laser heating fluorination technique. Oxygen

Organic/hybrid thin films deposited by matrix-assisted pulsed laser evaporation (MAPLE)

NASA Astrophysics Data System (ADS)

Stiff-Roberts, Adrienne D.; Ge, Wangyao

2017-12-01

Some of the most exciting materials research in the 21st century attempts to resolve the challenge of simulating, synthesizing, and characterizing new materials with unique properties designed from first principles. Achievements in such development for organic and organic-inorganic hybrid materials make them important options for electronic and/or photonic devices because they can impart multi-functionality, flexibility, transparency, and sustainability to emerging systems, such as wearable electronics. Functional organic materials include small molecules, oligomers, and polymers, while hybrid materials include inorganic nanomaterials (such as zero-dimensional quantum dots, one-dimensional carbon nanotubes, or two-dimensional nanosheets) combined with organic matrices. A critically important step to implementing new electronic and photonic devices using such materials is the processing of thin films. While solution-based processing is the most common laboratory technique for organic and hybrid materials, vacuum-based deposition has been critical to the commercialization of organic light emitting diodes based on small molecules, for example. Therefore, it is desirable to explore vacuum-based deposition of organic and hybrid materials that include larger macromolecules, such as polymers. This review article motivates the need for physical vapor deposition of polymeric and hybrid thin films using matrix-assisted pulsed laser evaporation (MAPLE), which is a type of pulsed laser deposition. This review describes the development of variations in the MAPLE technique, discusses the current understanding of laser-target interactions and growth mechanisms for different MAPLE variations, surveys demonstrations of MAPLE-deposited organic and hybrid materials for electronic and photonic devices, and provides a future outlook for the technique.

An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

NASA Astrophysics Data System (ADS)

Rohde, S.; Barnett, S. A.; Choi, C.-H.

1989-06-01

A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

Fabrication of a Quartz-Crystal-Microbalance/Optical-Waveguide Hybrid Sensor and In situ Evaluation of Vacuum-Evaporated Lead Phthalocyanine Thin Film

NASA Astrophysics Data System (ADS)

Shinbo, Kazunari; Uno, Akihiro; Hirakawa, Ryo; Baba, Akira; Ohdaira, Yasuo; Kato, Keizo; Kaneko, Futao

2013-05-01

In this study, we fabricated a novel quartz-crystal-microbalance (QCM)/optical-waveguide hybrid sensor. An in situ observation of a lead phthalocyanine (PbPc) thin-film deposition was conducted during vacuum evaporation, and the effectiveness of the sensor was demonstrated. The film thickness was obtained from the QCM frequency, and the optical absorption of the film was observed by optical waveguide spectroscopy using part of the QCM substrate without the electrode. The film absorption depends on the polarization direction, substrate temperature and deposition rate, owing to aggregate formation. The thickness dependence of the absorption property was also investigated.

Analysis of the moisture evaporation process during vacuum freeze-drying of koumiss and shubat

NASA Astrophysics Data System (ADS)

Shingisov, Azret Utebaevich; Alibekov, Ravshanbek Sultanbekovich

2017-05-01

The equation for the calculating of a moisture evaporation rate in the vacuum freeze-drying, wherein as a driving force instead of the generally accepted in the drying theory of Δt temperature difference, Δp pressure difference, Δc concentration difference, a difference of water activity in the product and the relative air humidity (a_{{w}} - \\varphi) is suggested. By using the proposed equation, the processes of vacuum freeze-drying of koumiss and shubat were analyzed, and it was found two drying periods: constant and falling. On the first drying period, a moisture evaporation rate of koumiss is j = 2.75 × 10-3 kg/(m2 h) and of shubat is j = 2.37 × 10-3 kg/(m2 h). On the second period, values decrease for koumiss from j = 2.65 × 10-3 kg/(m2 h) to j = 1.60 × 10-3 kg/(m2 h), and for shubat from j = 2.25 × 10-3 kg/(m2 h) to j = 1.62 × 10-3 kg/(m2 h). Specific humidity for koumiss is ueq = 0.61 kg/kg and for shubat is ueq = 0.58 kg/kg. The comparative analyze of the experimental data of the moisture evaporation rate versus the theoretical calculation shows that the approximation reliability is R2 = 0.99. Consequently, the proposed equation is useful for the analyzing a moisture evaporation rate during a vacuum freeze-drying of dairy products, including cultured milk foods.

Silicon Isotopic Fractionation of CAI-like Vacuum Evaporation Residues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knight, K; Kita, N; Mendybaev, R

2009-06-18

Calcium-, aluminum-rich inclusions (CAIs) are often enriched in the heavy isotopes of magnesium and silicon relative to bulk solar system materials. It is likely that these isotopic enrichments resulted from evaporative mass loss of magnesium and silicon from early solar system condensates while they were molten during one or more high-temperature reheating events. Quantitative interpretation of these enrichments requires laboratory determinations of the evaporation kinetics and associated isotopic fractionation effects for these elements. The experimental data for the kinetics of evaporation of magnesium and silicon and the evaporative isotopic fractionation of magnesium is reasonably complete for Type B CAI liquidsmore » (Richter et al., 2002, 2007a). However, the isotopic fractionation factor for silicon evaporating from such liquids has not been as extensively studied. Here we report new ion microprobe silicon isotopic measurements of residual glass from partial evaporation of Type B CAI liquids into vacuum. The silicon isotopic fractionation is reported as a kinetic fractionation factor, {alpha}{sub Si}, corresponding to the ratio of the silicon isotopic composition of the evaporation flux to that of the residual silicate liquid. For CAI-like melts, we find that {alpha}{sub Si} = 0.98985 {+-} 0.00044 (2{sigma}) for {sup 29}Si/{sup 28}Si with no resolvable variation with temperature over the temperature range of the experiments, 1600-1900 C. This value is different from what has been reported for evaporation of liquid Mg{sub 2}SiO{sub 4} (Davis et al., 1990) and of a melt with CI chondritic proportions of the major elements (Wang et al., 2001). There appears to be some compositional control on {alpha}{sub Si}, whereas no compositional effects have been reported for {alpha}{sub Mg}. We use the values of {alpha}Si and {alpha}Mg, to calculate the chemical compositions of the unevaporated precursors of a number of isotopically fractionated CAIs from CV chondrites

Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chander, Subhash, E-mail: sckhurdra@gmail.com; Purohit, A.; Lal, C.

2016-05-06

In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays anmore » important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.« less

Mean-field kinetic theory approach to evaporation of a binary liquid into vacuum

NASA Astrophysics Data System (ADS)

Frezzotti, A.; Gibelli, L.; Lockerby, D. A.; Sprittles, J. E.

2018-05-01

Evaporation of a binary liquid into near-vacuum conditions has been studied using numerical solutions of a system of two coupled Enskog-Vlasov equations. Liquid-vapor coexistence curves have been mapped out for different liquid compositions. The evaporation process has been investigated at a range of liquid temperatures sufficiently lower than the critical one for the vapor not to significantly deviate from the ideal behavior. It is found that the shape of the distribution functions of evaporating atoms is well approximated by an anisotropic Maxwellian distribution with different characteristic temperatures for velocity components normal and parallel to the liquid-vapor interface. The anisotropy reduces as the evaporation temperature decreases. Evaporation coefficients are computed based on the separation temperature and the maximum concentration of the less volatile component close to the liquid-vapor interface. This choice leads to values which are almost constant in the simulation conditions.

Directed Vapor Deposition: Low Vacuum Materials Processing Technology

DTIC Science & Technology

2000-01-01

constituent A Crucible with constituent B Electron beam AB Substrate Deposit Flux of A Flux of B Composition "Skull" melt Electron beam Coolant Copper ... crucible Evaporation target Evaporant material Vapor flux Fibrous Coating Surface a) b) sharp (0.5 mm) beam focussing. When used with multisource

Alloy vapor deposition using ion plating and flash evaporation

NASA Technical Reports Server (NTRS)

Spalvins, T.

1971-01-01

Method extends scope of ion plating technique to include deposition of alloy films without changing composition of plating alloy. Coatings flow with specimen material without chipping or peeling. Technique is most effective vacuum deposition method for depositing alloys for strong and lasting adherence.

Vapor pressure and evaporation rate of certain heat-resistant compounds in a vacuum at high temperatures

NASA Technical Reports Server (NTRS)

Bolgar, A. S.; Verkhoglyadova, T. S.; Samsonov, G. V.

1985-01-01

The vapor pressure and evaporation rate of borides of titanium, zirconium, and chrome; and of strontium and carbides of titanium, zirconium, and chrome, molybdenum silicide; and nitrides of titanium, niobium, and tantalum in a vacuum were studied. It is concluded that all subject compounds evaporate by molecular structures except AlB sub 12' which dissociates, losing the aluminum.

Carbonate deposition on tail feathers of ruddy ducks using evaporation ponds

USGS Publications Warehouse

Euliss, N.H.; Jarvis, R.L.; Gilmer, D.S.

1989-01-01

Substantial carbonate deposits were observed on rectrices of Ruddy Ducks (Oxyura jamaicensis) collected during 1982-1984 on evaporation ponds in the San Joaquin Valley, California. Carbonate deposits were composed of about 75% aragonite and 25% calcite, both polymorphous forms of CaCO3. Significantly more carbonate deposits were observed on Ruddy Ducks as length of exposure to agricultural drain water increased, during the 1983-1984 field season when salt concentrations in the ponds were higher, and in certain evaporation-pond systems.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1993-11-09

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of standard polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1995-03-07

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1993-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1995-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Superior stability for perovskite solar cells with 20% efficiency using vacuum co-evaporation.

PubMed

Zhu, Xuejie; Yang, Dong; Yang, Ruixia; Yang, Bin; Yang, Zhou; Ren, Xiaodong; Zhang, Jian; Niu, Jinzhi; Feng, Jiangshan; Liu, Shengzhong Frank

2017-08-31

Chemical composition and film quality are two key figures of merit for large-area high-efficiency perovskite solar cells. To date, all studies on mixed perovskites have used solution-processing, which results in imperfect surface coverage and pin-holes generated during solvent evaporation, execrably influencing the stability and efficiency of perovskite solar cells. Herein, we report our development using a vacuum co-evaporation deposition method to fabricate pin-hole-free cesium (Cs)-substituted perovskite films with complete surface coverage. Apart from the simplified procedure, the present method also promises tunable band gap, reduced trap-state density and longer carrier lifetime, leading to solar cell efficiency as high as 20.13%, which is among the highest reported for planar perovskite solar cells. The splendid performance is attributed to superior merits of the Cs-substituted perovskite film including tunable band gap, reduced trap-state density and longer carrier lifetime. Moreover, the Cs-substituted perovskite device without encapsulation exhibits significantly higher stability in ambient air compared with the single-component counterpart. When the Cs-substituted perovskite solar cells are stored in dark for one year, the PCE remains at 19.25%, degrading only 4.37% of the initial efficiency. The excellent stability originates from reduced lattice constant and relaxed strain in perovskite lattice by incorporating Cs cations into the crystal lattice, as demonstrated by the positive peak shifts and reduced peak width in X-ray diffraction analysis.

Treatment of a waste oil-in-water emulsion from a copper-rolling process by ultrafiltration and vacuum evaporation.

PubMed

Gutiérrez, Gemma; Lobo, Alberto; Benito, José M; Coca, José; Pazos, Carmen

2011-01-30

A process is proposed for the treatment of a waste oil-in-water (O/W) emulsion generated in an industrial copper-rolling operation. The use of demulsifier agents improves the subsequent treatment by techniques such as ultrafiltration (UF) or evaporation. The effluent COD is reduced up to 50% when the O/W emulsion is treated by UF using a flat 30 nm TiO(2) ceramic membrane (ΔP = 0.1 MPa) and up to 70% when it is treated by vacuum evaporation, after an emulsion destabilization pretreatment in both cases. Increases in the UF permeate flux and in the evaporation rate are observed when a chemical demulsifier is used in the pretreatment step. A combined process consisting of destabilization/settling, UF, and vacuum evaporation can yield a very high-quality aqueous effluent that could be used for process cooling or emulsion reformulation. Copyright © 2010 Elsevier B.V. All rights reserved.

Deposition of bi-dispersed particles in inkjet-printed evaporating colloidal drops

NASA Astrophysics Data System (ADS)

Sun, Ying; Joshi, Abhijit; Chhasatia, Viral

2010-11-01

In this study, the deposition behaviors of inkjet-printed evaporating colloidal drops consisting of bi-dispersed micro and nano-sized particles are investigated by fluorescence microscopy and SEM. The results on hydrophilic glass substrates show that, evaporatively-driven outward flow drives the nanoparticles to deposit close to the pinned contact line while an inner ring deposition is formed by microparticles. This size-induced particle separation is consistent with the existence of a wedge-shaped drop edge near the contact line region of an evaporating drop on a hydrophilic substrate. The replenishing evaporatively-driven flow assembles nanoparticles closer to the pinned contact line forming an outer ring of nanoparticles and this particle jamming further enhances the contact line pinning. Microparticles are observed to form an inner ring inside the nano-sized deposits. This size-induced particle separation presents a new challenge to the uniformity of functional materials in bioprinting applications where nanoparticles and micro-sized cells are mixed together. On the other hand, particle self-assembly based on their sizes provides enables easy and well-controlled pattern formation. The effects of particle size contrast, particle volume fraction, substrate surface energy, and relative humidity of the printing environment on particle separation are examined in detail.

The Radial Distribution Function (RDF) of Amorphous Selenium Obtained through the Vacuum Evaporator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guda, Bardhyl; Dede, Marie

2010-01-21

After the amorphous selenium obtained through the vacuum evaporator, the relevant diffraction intensity is taken and its processing is made. Further on the interferential function is calculated and the radial density function is defined. For determining these functions are used two methods, which were compared with each other and finally are received results for amorphous selenium RDF.

Vacuum vapor deposition

NASA Technical Reports Server (NTRS)

Poorman, Richard M. (Inventor); Weeks, Jack L. (Inventor)

1995-01-01

A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 10(exp -7) mm Hg

NASA Technical Reports Server (NTRS)

Buckley, Donald H.; Swikert, Max; Johnson, Robert L.

1961-01-01

The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.

Vacuum-integrated electrospray deposition for highly reliable polymer thin film.

PubMed

Park, Soohyung; Lee, Younjoo; Yi, Yeonjin

2012-10-01

Vacuum electrospray deposition (ESD) equipment was designed to prepare polymer thin films. The polymer solution can be injected directly into vacuum system through multi-stage pumping line, so that the solvent residues and ambient contaminants are highly reduced. To test the performance of ESD system, we fabricated organic photovoltaic cells (OPVCs) by injecting polymer solution directly onto the substrate inside a high vacuum chamber. The OPVC fabricated has the structure of Al∕P3HT:PCBM∕PEDOT:PSS∕ITO and was optimized by varying the speed of solution injection and concentration of the solution. The power conversion efficiency (PCE) of the optimized OPVC is 3.14% under AM 1.5G irradiation without any buffer layer at the cathode side. To test the advantages of the vacuum ESD, we exposed the device to atmosphere between the deposition steps of the active layer and cathode. This showed that the PCE of the vacuum processed device is 24% higher than that of the air exposed device and confirms the advantages of the vacuum prepared polymer film for high performance devices.

Vacuum deposition and curing of liquid monomers apparatus

DOEpatents

Affinito, John D.

1996-01-01

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Internal motion in high vacuum systems

NASA Astrophysics Data System (ADS)

Frank, J. M.

Three transfer and positioning mechanisms have been developed for the non-air exposed, multistep processing of components in vacuum chambers. The functions to be performed in all of the systems include ultraviolet/ozone cleaning, vacuum baking, deposition of thin films, and thermocompression sealing of the enclosures. Precise positioning of the components is required during the evaporation and sealing processes. The three methods of transporting and positioning the components were developed to accommodate the design criteria and goals of each individual system. The design philosophy, goals, and operation of the three mechanisms are discussed.

Vacuum deposition and curing of liquid monomers apparatus

DOEpatents

Affinito, J.D.

1996-08-20

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface. 3 figs.

Sheath expansion and plasma dynamics in the presence of electrode evaporation: Application to a vacuum circuit breaker

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarrailh, P.; LAPLACE, CNRS, F-31062 Toulouse; Schneider Electric, Centre de Recherche 38 TEC, 38050 Grenoble Cedex 09

2009-09-01

During the postarc dielectric recovery phase in a vacuum circuit breaker, a cathode sheath forms and expels the plasma from the electrode gap. The success or failure of current breaking depends on how efficiently the plasma is expelled from the electrode gap. The sheath expansion in the postarc phase can be compared to sheath expansion in plasma immersion ion implantation except that collisions between charged particles and atoms generated by electrode evaporation may become important in a vacuum circuit breaker. In this paper, we show that electrode evaporation plays a significant role in the dynamics of the sheath expansion inmore » this context not only because charged particle transport is no longer collisionless but also because the neutral flow due to evaporation and temperature gradients may push the plasma toward one of the electrodes. Using a hybrid model of the nonequilibrium postarc plasma and cathode sheath coupled with a direct simulation Monte Carlo method to describe collisions between heavy species, we present a parametric study of the sheath and plasma dynamics and of the time needed for the sheath to expel the plasma from the gap for different values of plasma density and electrode temperatures at the beginning of the postarc phase. This work constitutes a preliminary step toward understanding and quantifying the risk of current breaking failure of a vacuum arc.« less

Sheath expansion and plasma dynamics in the presence of electrode evaporation: Application to a vacuum circuit breaker

NASA Astrophysics Data System (ADS)

Sarrailh, P.; Garrigues, L.; Hagelaar, G. J. M.; Boeuf, J. P.; Sandolache, G.; Rowe, S.

2009-09-01

During the postarc dielectric recovery phase in a vacuum circuit breaker, a cathode sheath forms and expels the plasma from the electrode gap. The success or failure of current breaking depends on how efficiently the plasma is expelled from the electrode gap. The sheath expansion in the postarc phase can be compared to sheath expansion in plasma immersion ion implantation except that collisions between charged particles and atoms generated by electrode evaporation may become important in a vacuum circuit breaker. In this paper, we show that electrode evaporation plays a significant role in the dynamics of the sheath expansion in this context not only because charged particle transport is no longer collisionless but also because the neutral flow due to evaporation and temperature gradients may push the plasma toward one of the electrodes. Using a hybrid model of the nonequilibrium postarc plasma and cathode sheath coupled with a direct simulation Monte Carlo method to describe collisions between heavy species, we present a parametric study of the sheath and plasma dynamics and of the time needed for the sheath to expel the plasma from the gap for different values of plasma density and electrode temperatures at the beginning of the postarc phase. This work constitutes a preliminary step toward understanding and quantifying the risk of current breaking failure of a vacuum arc.

Thermal Vacuum Testing of a Proto-flight Miniature Loop Heat Pipe with Two Evaporators and Two Condensers

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura

2011-01-01

This paper describes thermal vacuum testing of a proto-flight miniature loop heat pipe (MLHP) with two evaporators and two condensers designed for future small systems applications requiring low mass, low power and compactness. Each evaporator contains a wick with an outer diameter of 6.35 mm, and each has its own integral compensation chamber (CC). Miniaturization of the loop components reduces the volume and mass of the thermal system. Multiple evaporators provide flexibility for placement of instruments that need to be maintained at the same temperature, and facilitate heat load sharing among instruments, reducing the auxiliary heater power requirement. A flow regulator is used to regulate heat dissipations between the two condensers, allowing flexible placement of radiators on the spacecraft. A thermoelectric converter (TEC) is attached to each CC for control of the operating temperature and enhancement of start-up success. Tests performed include start-up, power cycle, sink temperature cycle, high power and low power operation, heat load sharing, and operating temperature control. The proto-flight MLHP demonstrated excellent performance in the thermal vacuum test. The loop started successfully and operated stably under various evaporator heat loads and condenser sink temperatures. The TECs were able to maintain the loop operating temperature within b1K of the desired set point temperature at all power levels and all sink temperatures. The un-powered evaporator would automatically share heat from the other powered evaporator. The flow regulator was able to regulate the heat dissipation among the radiators and prevent vapor from flowing into the liquid line.

Long length coated conductor fabrication by inclined substrate deposition and evaporation

NASA Astrophysics Data System (ADS)

Prusseit, W.; Hoffmann, C.; Nemetschek, R.; Sigl, G.; Handke, J.; Lümkemann, A.; Kinder, H.

2006-06-01

The commercial development of coated conductors is rapidly progressing. As a result we present an economic route to produce second generation HTS tape from the initial substrate preparation to the final metal coating. The most important and technically challenging steps are the deposition of an oriented buffer layer and the superconductor film in a reel-to-reel configuration. New evaporation techniques have been developed to enable reliable, high rate tape coating. Highly oriented MgO - buffer layers are realized by inclined substrate deposition (ISD) and DyBCO is deposited by simple e-gun evaporation yielding critical currents beyond 200 A/cm. Coated conductors have been fabricated up to 40 m length and are currently tested in a variety of applications.

Vacuum and low oxygen pressure influence on BaFe12O19 film deposited by pulse laser deposition

NASA Astrophysics Data System (ADS)

Kumar, Pawan; Gaur, Anurag; Choudhary, R. J.

2018-05-01

BaFe12O19 hexaferrite thin films are deposited on Si (111) substrate by the pulse laser deposition (PLD) technique in high vacuum 10-6 Torr and low oxygen pressure (10 mTorr) at 650°C substrate temperature. The effects of high vacuum and low pressure on magnetic and optical properties are studied. These films are characterized by the x-ray diffractometer (XRD), SQUID-VSM magnetometer, and Photo-luminescence spectroscopy. XRD pattern reveals that the BaFe12O19 film well formed in both environments without any impurity pick. High magnetic saturazation 317 emu/cm3 and coercivity 130 Oe are observed for the film deposited in vacuum. Photoluminescence emission spectrum of BaFe12O19 film reveals that the higher intensity emission peak at ˜372 nm under the excitation wavelength of 270 nm is observed for the film grown in vacuum.

Organic ferroelectric evaporator with substrate cooling and in situ transport capabilities.

PubMed

Foreman, K; Labedz, C; Shearer, M; Adenwalla, S

2014-04-01

We report on the design, operation, and performance of a thermal evaporation chamber capable of evaporating organic thin films. Organic thin films are employed in a diverse range of devices and can provide insight into fundamental physical phenomena. However, growing organic thin films is often challenging and requires very specific deposition parameters. The chamber presented here is capable of cooling sample substrates to temperatures below 130 K and allows for the detachment of the sample from the cooling stage and in situ transport. This permits the use of multiple deposition techniques in separate, but connected, deposition chambers without breaking vacuum and therefore provides clean, well characterized interfaces between the organic thin film and any adjoining layers. We also demonstrate a successful thin film deposition of an organic material with a demanding set of deposition parameters, showcasing the success of this design.

Deposition of Nanostructured CdS Thin Films by Thermal Evaporation Method: Effect of Substrate Temperature

PubMed Central

Memarian, Nafiseh; Rozati, Seyeed Mohammad; Concina, Isabella

2017-01-01

Nanocrystalline CdS thin films were grown on glass substrates by a thermal evaporation method in a vacuum of about 2 × 10−5 Torr at substrate temperatures ranging between 25 °C and 250 °C. The physical properties of the layers were analyzed by transmittance spectra, XRD, SEM, and four-point probe measurements, and exhibited strong dependence on substrate temperature. The XRD patterns of the films indicated the presence of single-phase hexagonal CdS with (002) orientation. The structural parameters of CdS thin films (namely crystallite size, number of grains per unit area, dislocation density and the strain of the deposited films) were also calculated. The resistivity of the as-deposited films were found to vary in the range 3.11–2.2 × 104 Ω·cm, depending on the substrate temperature. The low resistivity with reasonable transmittance suggest that this is a reliable way to fine-tune the functional properties of CdS films according to the specific application. PMID:28773133

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J.; Halpern, B.L.

1994-10-18

A method and apparatus are disclosed for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases. 8 figs.

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, Jerome J.; Halpern, Bret L.

1994-01-01

A method and apparatus for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases.

New evaporator station for the center for accelerator target science

NASA Astrophysics Data System (ADS)

Greene, John P.; Labib, Mina

2018-05-01

As part of an equipment grant provided by DOE-NP for the Center for Accelerator Target Science (CATS) initiative, the procurement of a new, electron beam, high-vacuum deposition system was identified as a priority to insure reliable and continued availability of high-purity targets. The apparatus is designed to contain TWO electron beam guns; a standard 4-pocket 270° geometry source as well as an electron bombardment source. The acquisition of this new system allows for the replacement of TWO outdated and aging vacuum evaporators. Also included is an additional thermal boat source, enhancing our capability within this deposition unit. Recommended specifications for this system included an automated, high-vacuum pumping station, a deposition chamber with a rotating and heated substrate holder for uniform coating capabilities and incorporating computer-controlled state-of-the-art thin film technologies. Design specifications, enhanced capabilities and the necessary mechanical modifications for our target work are discussed.

Formation of Cadmium-Sulfide Nanowhiskers via Vacuum Evaporation and Condensation in a Quasi-Closed Volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belyaev, A. P., E-mail: Alexei.Belyaev@pharminnotech.com; Antipov, V. V.; Rubets, V. P.

Structural and technological studies of processes in which cadmium-sulfide nanowhiskers are synthesized in a quasi-closed volume by the method of vacuum evaporation and condensation are reported. It is demonstrated that the processes are in agreement with the classical vapor–liquid–crystal model. Micrographs of the objects in different formation stages are presented.

Thick tellurium target preparation by vacuum deposition

NASA Astrophysics Data System (ADS)

Stolarz, Anna

1999-12-01

Tellurium targets of thickness up to 6.5 mg/cm 2 on carbon backings were prepared by vacuum deposition. The influence of the crucible dimension, treatment of the backing foil by glow discharge and substrate cooling on the Te sticking efficiency was studied in order to achieve the best yield.

Micromodel observations of evaporative drying and salt deposition in porous media

NASA Astrophysics Data System (ADS)

Rufai, Ayorinde; Crawshaw, John

2017-12-01

Most evaporation experiments using artificial porous media have focused on single capillaries or sand packs. We have carried out, for the first time, evaporation studies on a 2.5D micromodel based on a thin section of a sucrosic dolomite rock. This allowed direct visual observation of pore-scale processes in a network of pores. NaCl solutions from 0 wt. % (de-ionized water) to 36 wt. % (saturated brine) were evaporated by passing dry air through a channel in front of the micromodel matrix. For de-ionized water, we observed the three classical periods of evaporation: the constant rate period (CRP) in which liquid remains connected to the matrix surface, the falling rate period, and the receding front period, in which the capillary connection is broken and water transport becomes dominated by vapour diffusion. However, when brine was dried in the micromodel, we observed that the length of the CRP decreased with increasing brine concentration and became almost non-existent for the saturated brine. In the experiments with brine, the mass lost by evaporation became linear with the square root of time after the short CRP. However, this is unlikely to be due to capillary disconnection from the surface of the matrix, as salt crystals continued to be deposited in the channel above the matrix. We propose that this is due to salt deposition at the matrix surface progressively impeding hydraulic connectivity to the evaporating surface.

Solar cells for lunar applications by vacuum evaporation of lunar regolith materials

NASA Technical Reports Server (NTRS)

Ignatiev, Alex

1991-01-01

The National Space Exploration Initiative, specifically the Lunar component, has major requirements for technology development of critical systems, one of which is electrical power. The availability of significant electrical power on the surface of the Moon is a principal driver defining the complexity of the lunar base. Proposals to generate power on the Moon include both nuclear and solar (photovoltaic) systems. A more efficient approach is to attempt utilization of the existing lunar resources to generate the power systems. Synergism may occur from the fact that there have already been lunar materials processing techniques proposed for the extraction of oxygen that would have, as by-products, materials that could be specifically used to generate solar cells. The lunar environment is a vacuum with pressures generally in the 1 x 10(exp -10) torr range. Such conditions provide an ideal environment for direct vacuum deposition of thin film solar cells using the waste silicon, iron, and TiO2 available from the lunar regolith processing meant to extract oxygen. It is proposed, therefore, to grow by vacuum deposition, thin film silicon solar cells from the improved regolith processing by-products.

Vacuum Deposition From A Welding Torch

NASA Technical Reports Server (NTRS)

Poorman, R. M.

1993-01-01

Process derived from arc welding produces films of high quality. Modified gas/tungsten-arc welding process developed for use in outer space. Welding apparatus in process includes hollow tungsten electrode through which inert gas flows so arc struck between electrode and workpiece in vacuum of space. Offers advantages of fast deposition, possibility of applying directional impetus to flow of materials, very low pressure at surface being coated, and inert environment.

Reflectance of evaporated rhenium and tungsten films in the vacuum ultraviolet from 300 to 2000 A.

NASA Technical Reports Server (NTRS)

Cox, J. T.; Hass, G.; Ramsey, J. B.; Hunter, W. R.

1972-01-01

Discussion of the dependence of the reflectance of Re and W on the substrate temperature during deposition, film thickness, and aging during exposure to air. Re and W of 99.99% purity were evaporated with a 6-kW fine-focused electron gun and deposited on glass and fused quartz plates of various temperatures ranging from 40 to 500 C. With Re, films of highest reflectance were obtained by evaporation onto unheated substrates, whereas with W, heating of the substrate greatly increased the reflectance of the deposited films. For both metals, the reflectance losses during extended exposure to air remained rather small, indicating that the oxide films formed on both film materials at room temperature were very thin.

Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor

PubMed Central

2018-01-01

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner. PMID:29363979

Dynamic Control of Particle Deposition in Evaporating Droplets by an External Point Source of Vapor.

PubMed

Malinowski, Robert; Volpe, Giovanni; Parkin, Ivan P; Volpe, Giorgio

2018-02-01

The deposition of particles on a surface by an evaporating sessile droplet is important for phenomena as diverse as printing, thin-film deposition, and self-assembly. The shape of the final deposit depends on the flows within the droplet during evaporation. These flows are typically determined at the onset of the process by the intrinsic physical, chemical, and geometrical properties of the droplet and its environment. Here, we demonstrate deterministic emergence and real-time control of Marangoni flows within the evaporating droplet by an external point source of vapor. By varying the source location, we can modulate these flows in space and time to pattern colloids on surfaces in a controllable manner.

In-situ vacuum deposition technique of lithium on neutron production target for BNCT

NASA Astrophysics Data System (ADS)

Ishiyama, S.; Baba, Y.; Fujii, R.; Nakamura, M.; Imahori, Y.

2012-10-01

For the purpose of avoiding the radiation blistering of the lithium target for neutron production in BNCT (Boron Neutron Capture Therapy) device, trilaminar Li target, of which palladium thin layer was inserted between cupper substrate and Li layer, was newly designed. In-situ vacuum deposition and electrolytic coating techniques were applied to validate the method of fabrication of the Li/Pd/Cu target, and the layered structures of the synthesized target were characterized. In-situ vacuum re-deposition technique was also established for repairing and maintenance for lithium target damaged. Following conclusions were derived; (1) Uniform lithium layers with the thickness from 1.6 nm to a few hundreds nanometer were formed on Pd/Cu multilayer surface by in situ vacuum deposition technique using metallic lithium as a source material. (2) Re-deposition of lithium layer on Li surface can be achieved by in situ vacuum deposition technique. (3) Small amount of water and carbonate was observed on the top surface of Li. But the thickness of the adsorbed layer was less than monolayer, which will not affect the quality of the Li target. (4) The formation of Pd-Li alloy layer was observed at the Pd and Li interface. The alloy layer would contribute to the stability of the Li layer.

Analysis of plasma-controlled laser evaporation of Al target in vacuum

NASA Astrophysics Data System (ADS)

Mazhukin, Vladimir I.; Nossov, Vadim V.; Smurov, Igor Y.

2004-04-01

The plasma-controlled evaporation of the Al target induced by the laser pulse with intensity of 8 x 108 W/cm2 and wavelength of 1.06 μm is analyzed with account for the two-dimensional effects. The self consistent model is applied, consisting of the heat transfer equation in condensed medium, the system of radiation gas dynamics in evaporated substance, and the Knudsen layer model at the two media boundary. It is established that the phase transition of the target surface is controlled by the two factors: the surface temperature that depends on the transmitted radiation intensity and the plasma pressure, governed by the expansion regime. The process comes through three characteristics stages -- the sonic evaporation at the beginning, the condensation during the period of plasma formation and initial expansion and, finally, the recommence of evaporation in subsonic regime after the partial brightening of the plasma. During the subsonic evaporation stage the vapor flow and the mass removal rate is much higher near the beam boundaries than in the center due to smaller plasma counter-pressure. The vapor plasma pattern is characterized by the dense hot zone near the surface where the deposition of laser energy occurs, and rapid decrease of density outside the zone due to three-dimensional expansion. The application of the laser beam of smaller radius at the same intensity leads to the formation of more rarefied and more transparent plasma, that allows to improve the mass removal efficiency.

Optical investigation of vacuum evaporated Se80-xTe20Sbx (x = 0, 6, 12) amorphous thin films

NASA Astrophysics Data System (ADS)

Deepika; Singh, Hukum

2017-09-01

Amorphous thin films of Se80-xTe20Sbx (x = 0, 6, 12) chalcogenide glasses has been deposited onto pre-cleaned glass substrate using thermal evaporation technique under a vacuum of 10-5 Torr. The absorption and transmission spectra of these thin films have been recorded using UV spectrophotometer in the spectral range 400-2500 nm at room temperature. Swanepoel envelope method has been employed to obtain film thickness and optical constants such as refractive index, extinction coefficient and dielectric constant. The optical band gap of the samples has been calculated using Tauc relation. The study reveals that optical band gap decreases on increase in Sb content. This is due to decrease in average single bond energy calculated using chemical bond approach. The values of urbach energy has also been computed to support the above observation. Variation of refractive index has also been studies in terms of wavelength and energy using WDD model and values of single oscillator energy and dispersion energy has been obtained.

Thermal Vacuum Testing of a Multi-Evaporator Miniature Loop Heat Pipe

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura; Nagano, Hosei

2008-01-01

Under NASA's New Millennium Program Space Technology 8 Project, four experiments are being developed for future small system applications requiring low mass, low power, and compactness. GSFC is responsible for developing the Thermal Loop experiment, which is an advanced thermal control system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and condensers. The objective is to validate the operation of an MLHP, including reliable start-ups, steady operation, heat load sharing, and tight temperature control over the range of 273K to 308K. An MLHP Breadboard has been built and tested for 1200 hours under the laboratory environment and 500 hours in a thermal vacuum chamber. Results of the TV tests are presented here.

Enhanced Evaporation Strength through Fast Water Permeation in Graphene-Oxide Deposition

PubMed Central

Li Tong, Wei; Ong, Wee-Jun; Chai, Siang-Piao; Tan, Ming K.; Mun Hung, Yew

2015-01-01

The unique characteristic of fast water permeation in laminated graphene oxide (GO) sheets has facilitated the development of ultrathin and ultrafast nanofiltration membranes. Here we report the application of fast water permeation property of immersed GO deposition for enhancing the performance of a GO/water nanofluid charged two-phase closed thermosyphon (TPCT). By benchmarking its performance against a silver oxide/water nanofluid charged TPCT, the enhancement of evaporation strength is found to be essentially attributed to the fast water permeation property of GO deposition instead of the enhanced surface wettability of the deposited layer. The expansion of interlayer distance between the graphitic planes of GO deposited layer enables intercalation of bilayer water for fast water permeation. The capillary force attributed to the frictionless interaction between the atomically smooth, hydrophobic carbon structures and the well-ordered hydrogen bonds of water molecules is sufficiently strong to overcome the gravitational force. As a result, a thin water film is formed on the GO deposited layers, inducing filmwise evaporation which is more effective than its interfacial counterpart, appreciably enhanced the overall performance of TPCT. This study paves the way for a promising start of employing the fast water permeation property of GO in thermal applications. PMID:26100977

A study on the evaporation process with multiple point-sources

NASA Astrophysics Data System (ADS)

Jun, Sunghoon; Kim, Minseok; Kim, Suk Han; Lee, Moon Yong; Lee, Eung Ki

2013-10-01

In Organic Light Emitting Display (OLED) manufacturing processes, there is a need to enlarge the mother glass substrate to raise its productivity and enable OLED TV. The larger the size of the glass substrate, the more difficult it is to establish a uniform thickness profile of the organic thin-film layer in the vacuum evaporation process. In this paper, a multiple point-source evaporation process is proposed to deposit a uniform organic layer uniformly. Using this method, a uniformity of 3.75% was achieved along a 1,300 mm length of Gen. 5.5 glass substrate (1300 × 1500 mm2).

MINERVA: A facility to study Microstructure and INterface Evolution in Realtime under VAcuum

NASA Astrophysics Data System (ADS)

Nicklin, Chris; Martinez-Hardigree, Josue; Warne, Adam; Green, Stephen; Burt, Martin; Naylor, John; Dorman, Adam; Wicks, Dean; Din, Salahud; Riede, Moritz

2017-10-01

A sample environment to enable real-time X-ray scattering measurements to be recorded during the growth of materials by thermal evaporation in vacuum is presented. The in situ capabilities include studying microstructure development with time or during exposure to different environmental conditions, such as temperature and gas pressure. The chamber provides internal slits and a beam stop, to reduce the background scattering from the X-rays passing through the entrance and exit windows, together with highly controllable flux rates of the evaporants. Initial experiments demonstrate some of the possibilities by monitoring the growth of bathophenanthroline (BPhen), a common molecule used in organic solar cells and organic light emitting diodes, including the development of the microstructure with time and depth within the film. The results show how BPhen nanocrystal structures coarsen at room temperature under vacuum, highlighting the importance of using real time measurements to understand the as-deposited pristine film structure and its development with time. More generally, this sample environment is versatile and can be used for investigation of structure-property relationships in a wide range of vacuum deposited materials and their applications in, for example, optoelectronic devices and energy storage.

Relationship between microstructural and magnetic properties of PrCo-based films prepared by the vacuum evaporation method

NASA Astrophysics Data System (ADS)

Fersi, R.; Bouzidi, W.; Bezergheanu, A.; Cizmas, C. B.; Bessais, L.; Mliki, N.

2018-04-01

In this work, Ce2Ni7 type structural PrCo-based films were deposited on Si(1 0 0) substrate by ultra-high (UHV) vacuum evaporation process. The structural and magnetic properties of these films have been performed using X-ray diffraction (XRD), atomic force microscopy (AFM), vibrating sample magnetometer (VSM) and magnetic force microscopy (MFM) techniques. Two effects on structural and magnetic properties of PrCo films have been investigated: the effect of the annealing temperature (Ta) and the effect of the variation of the magnetic X-layer thickness. The as deposited PrCo films have a magnetic coercivity (Hc) of about 40-100 Oe. But after annealing at 600 °C, Hc has increased hight about 9.5 kOe for PrCo(X = 20 nm) and 10.2 kOe for PrCo(X = 50 nm) were observed. The magnetic properties were affected by the thickness due to the morphology, also the relationship between the intergrain exchange coupling (IEC), the size and quantity of the PrCo grains. The hight extrinsic properties of Hc = 10.2 kOe, maximum energy product (BH)max of 5.12 MGOe and remanence ratio Mr /Ms = 0.53 are reported for the PrCo(X = 50 nm) films. These properties are highly desirable for extremely high-density magnetic recording media applications.

APPARATUS FOR VACUUM DEPOSITION OF METALS

DOEpatents

Milleron, N.

1962-03-13

An apparatus and a method are described for continuous vacuum deposition of metals for metallic coatings, for ultra-high vacuum work, for purification of metals, for maintaining high-density electron currents, and for other uses. The apparatus comprises an externally cooled feeder tube extending into a container and adapted to feed metal wire or strip so that it emerges in a generally vertical position therein. The tube also provides shielding from the heat produced by an electron beam therein focused to impinge from a vertical direction upon the tip of the emerging wire. By proper control of the wire feed, coolant feed, and electron beam intensity, a molten ball of metal forms upon the emerging tip and remains self-supported thereon by the interaction of various forces. The metal is vaporized and travels in a line of sight direction, while additional wire is fed from the tube, so that the size of the molten ball remains constant. In the preferred embodiments, the wire is selected from a number of gettering metals and is degassed by electrical resistance in an adjacent chamber which is also partially evacuated. The wire is then fed through the feed tube into the electron beam and vaporizes and adsorbs gases to provide pumping action while being continuously deposited upon surfaces within the chamber. Ion pump electrodes may also be provided within line of sight of the vaporizing metal source to enhance the pumping action. (AEC)

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

PubMed Central

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-01-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility. PMID:27958304

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-12-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility.

Effect of thickness on physical properties of electron beam vacuum evaporated CdZnTe thin films for tandem solar cells

NASA Astrophysics Data System (ADS)

Chander, Subhash; Dhaka, M. S.

2016-10-01

The thickness and physical properties of electron beam vacuum evaporated CdZnTe thin films have been optimized in the present work. The films of thickness 300 nm and 400 nm were deposited on ITO coated glass substrates and subjected to different characterization tools like X-ray diffraction (XRD), UV-Vis spectrophotometer, source meter and scanning electron microscopy (SEM) to investigate the structural, optical, electrical and surface morphological properties respectively. The XRD results show that the as-deposited CdZnTe thin films have zinc blende cubic structure and polycrystalline in nature with preferred orientation (111). Different structural parameters are also evaluated and discussed. The optical study reveals that the optical transition is found to be direct and energy band gap is decreased for higher thickness. The transmittance is found to increase with thickness and red shift observed which is suitable for CdZnTe films as an absorber layer in tandem solar cells. The current-voltage characteristics of deposited films show linear behavior in both forward and reverse directions as well as the conductivity is increased for higher film thickness. The SEM studies show that the as-deposited CdZnTe thin films are found to be homogeneous, uniform, small circle-shaped grains and free from crystal defects. The experimental results confirm that the film thickness plays an important role to optimize the physical properties of CdZnTe thin films for tandem solar cell applications as an absorber layer.

Growth of BaSi2 film on Ge(100) by vacuum evaporation and its photoresponse properties

NASA Astrophysics Data System (ADS)

Trinh, Cham Thi; Nakagawa, Yoshihiko; Hara, Kosuke O.; Kurokawa, Yasuyoshi; Takabe, Ryota; Suemasu, Takashi; Usami, Noritaka

2017-05-01

We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 µs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.

Effects of film thickness on the linear and nonlinear refractive index of p-type SnO films deposited by e-beam evaporation process

NASA Astrophysics Data System (ADS)

El-Gendy, Y. A.

2017-12-01

Tin monoxide (SnO) films of different thickness have been deposited onto glass substrates at vacuum pressure of ∼ 8 × 10-6 mbar using an e-beam evaporation system. A hot probe test revealed that the deposited films showed p-type conduction. The structure characterization and phase purity of the deposited films was confirmed using X-ray diffraction (XRD) and Raman spectroscopy. The optical transmission and reflection spectra of the deposited films recorded in the wavelength range 190-2500 nm were used to calculate the optical constants employing the Murmann's exact equations. The refractive index dispersion was adequately described by the well-known effective-single-oscillator model proposed by Wemple-DiDomenico, whereby the dispersion parameters were calculated. The nonlinear refractive index and nonlinear optical susceptibility of the deposited films were successfully evaluated using the Miller empirical relations. The lattice dielectric constant and the carrier concentration to the effective mass ratio were also calculated as a function of film thickness using the Spitzer and Fan model. The variation of the optical band gap of the deposited films as a function of film thickness was also presented.

Simple evaporation controller for thin-film deposition from a resistively heated boat

NASA Technical Reports Server (NTRS)

Scofield, John H.; Bajuk, Lou; Mohler, William

1990-01-01

A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

Evaporative Optical Marangoni Assembly: Tailoring the Three-Dimensional Morphology of Individual Deposits of Nanoparticles from Sessile Drops.

PubMed

Anyfantakis, Manos; Varanakkottu, Subramanyan Namboodiri; Rudiuk, Sergii; Morel, Mathieu; Baigl, Damien

2017-10-25

We have recently devised the evaporative optical Marangoni assembly (eOMA), a novel and versatile interfacial flow-based method for directing the deposition of colloidal nanoparticles (NPs) on solid substrates from evaporating sessile drops along desired patterns using shaped UV light. Here, we focus on a fixed UV spot irradiation resulting in a cylinder-like deposit of assembled particles and show how the geometrical features of the single deposit can be tailored in three dimensions by simply adjusting the optical conditions or the sample composition, in a quantitative and reproducible manner. Sessile drops containing cationic NPs and a photosensitive surfactant at various concentrations are allowed to evaporate under a single UV beam with a diameter much smaller than that of the drop. After complete evaporation, the geometrical characteristics of the NP deposits are precisely assessed using optical profilometry. We show that both the volume and the radial size of the light-directed NP deposit can be adjusted by varying the diameter or the intensity of the UV beam or alternatively by changing the concentration of the photosensitive surfactant. Notably, in all these cases, the deposits display an almost constant median height corresponding to a few layers of particles. Moreover, both the radial and the axial extent of the patterns are tuned by changing the NP concentration. These results are explained by the correlation among the strength of Marangoni flow, the particle trapping efficiency, and the volume of the deposit, and by the role of evaporation-driven flow in strongly controlling the deposit height. Finally, we extend the versatility of eOMA by demonstrating that NPs down to 30 nm in diameter can be effectively patterned on glass or polymeric substrates.

Transparent electrical conducting films by activated reactive evaporation

DOEpatents

Bunshah, Rointan; Nath, Prem

1982-01-01

Process and apparatus for producing transparent electrical conducting thin films by activated reactive evaporation. Thin films of low melting point metals and alloys, such as indium oxide and indium oxide doped with tin, are produced by physical vapor deposition. The metal or alloy is vaporized by electrical resistance heating in a vacuum chamber, oxygen and an inert gas such as argon are introduced into the chamber, and vapor and gas are ionized by a beam of low energy electrons in a reaction zone between the resistance heater and the substrate. There is a reaction between the ionized oxygen and the metal vapor resulting in the metal oxide which deposits on the substrate as a thin film which is ready for use without requiring post deposition heat treatment.

Optical properties of YbF3-CaF2 composite thin films deposited by electron-beam evaporation

NASA Astrophysics Data System (ADS)

Wang, Songlin; Mi, Gaoyuan; Zhang, Jianfu; Yang, Chongmin

2018-03-01

We studied electron-beam evaporated YbF3-CaF2 composite films on ZnS substrate at different deposition parameters. The optical properties of films have been fitted, the surface roughness have been measured by AFM. The results of experiments indicated that increased the refractive indices, extinction coefficients, and surface roughness at higher deposition rate. The refractive index of composite film deposited by electron-beam evaporation with assisted-ion source was obviously higher than it without assisted-ion source.

Evolution of gettering technologies for vacuum tubes to getters for MEMS

NASA Astrophysics Data System (ADS)

Amiotti, M.

2008-05-01

Getter materials are technically proven and industrially accepted practical ways to maintain vacuum inside hermetically sealed tubes or devices to assure high reliability and long lifetime of the operating devices. The most industrially proven vacuum tube is the cathode rays tubes (CRTs), where large surfaces are available for the deposition of an evaporated barium film by a radio frequency inductive heating of a stainless steel container filled with a BaAl4 powder mixed to Ni powder. The evolution of the CRTs manufacturing technologies required also new types of barium getters able to withstand some thermal process in air without any deterioration of the evaporation characteristics. In other vacuum tubes such as traveling waves tubes, the space available for the evaporation of a barium film and the sorption capacity required to assure the vacuum for the lifetime of the devices did not allow the use of the barium film, prompting the development of sintered non evaporable getter pills that can be activated during the manufacturing process or by flowing current through an embedded resistance. The same sintered non evaporable getter pills could find usage also in evacuated parts to thermally isolate the infrared sensors for different final applications. In high energy physics particle accelerators, the getter technology moved from localized vacuum getter pumps or getter strips to a getter coating over the surface of vacuum chambers in order to guarantee a more uniform pumping speed. With the advent of solid state electronics, new challenges faced the getter technology to assure long life to vacuum or inert gas filled hermetical packages containing microelectronic devices, especially in the telecommunication and military applications. A well known problem of GaAs devices with Pd or Pt metalization is the H2 poisoning of the metal gate: to prevent this degradation a two layer getter film has been develop to absorb a large quantity of H2 per unit of getter surface. The

Photolithographic patterning of vacuum-deposited organic light emitting devices

NASA Astrophysics Data System (ADS)

Tian, P. F.; Burrows, P. E.; Forrest, S. R.

1997-12-01

We demonstrate a photolithographic technique to fabricate vacuum-deposited organic light emitting devices. Photoresist liftoff combined with vertical deposition of the emissive organic materials and the metal cathode, followed by oblique deposition of a metal cap, avoids the use of high processing temperatures and the exposure of the organic materials to chemical degradation. The unpackaged devices show no sign of deterioration in room ambient when compared with conventional devices fabricated using low-resolution, shadow mask patterning. Furthermore, the devices are resistant to rapid degradation when operated in air for extended periods. This work illustrates a potential foundation for the volume production of very high-resolution, full color, flat panel displays based on small molecular weight organic light emitting devices.

Vacuum Ultraviolet Radiation Desorption of Molecular Contaminants Deposited on Quartz Crystal Microbalances

NASA Technical Reports Server (NTRS)

Albyn, Keith; Burns, Dewitt

2006-01-01

Recent quartz crystal microbalance measurements made in the Marshall Space Flight Center, Photo-Deposition Facility, for several materials, recorded a significant loss of deposited contaminants when the deposition surface of the microbalance was illuminated by a deuterium lamp. These measurements differ from observations made by other investigators in which the rate of deposition increased significantly when the deposition surface was illuminated with vacuum ultraviolet radiation. These observations suggest that the accelerated deposition of molecular contaminants on optically sensitive surfaces is dependant upon the contaminant being deposited and must be addressed during the materials selection process by common material screening techniques.

Method for producing evaporation inhibiting coating for protection of silicon--germanium and silicon--molybdenum alloys at high temperatures in vacuum

DOEpatents

Chao, P.J.

1974-01-01

A method is given for protecting Si--Ge and Si-- Mo alloys for use in thermocouples. The alloys are coated with silicon to inhibit the evaporation of the alloys at high tempenatures in a vacuum. Specific means and methods are provided. (5 fig) (Official Gazette)

Studies of Niobium Thin Film Produced by Energetic Vacuum Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genfa Wu; Anne-Marie Valente; H. Phillips

2004-05-01

An energetic vacuum deposition system has been used to study deposition energy effects on the properties of niobium thin films on copper and sapphire substrates. The absence of working gas avoids the gaseous inclusions commonly seen with sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with surface morphology and crystal orientation measurements by AFM inspection, XRD and TEM analysis. The results show that niobium thin films on sapphire substrate exhibit the best cryogenic properties at deposition energy around 123 eV.more » The TEM analysis revealed that epitaxial growth of film was evident when deposition energy reaches 163 eV for sapphire substrate. Similarly, niobium thin film on copper substrate shows that film grows more oriented with higher deposition energy and grain size reaches the scale of the film thickness at the deposition energy around 153 eV.« less

Electrical and optical properties of C46H22N8O4KM (M=Co, Fe, Pb) molecular-material thin films prepared by the vacuum thermal evaporation technique.

PubMed

Sánchez-Vergara, M E; Ruiz Farfán, M A; Alvarez, J R; Ponce Pedraza, A; Ortiz, A; Alvarez Toledano, C

2007-03-01

In this work, the synthesis of new materials formed from metallic phthalocyanines (Pcs) and double potassium salt from 1,8-dihydroxianthraquinone is reported. The newly synthesized materials were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), infrared (IR) and Ultraviolet-visible (UV-vis) spectroscopy. The powder and thin-film samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds as in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The effect of temperature on conductivity and electrical conduction mechanism was measured in the thin films (approximately 137 nm thickness). They showed a semiconductor-like behaviour with an optical activation energy arising from indirect transitions of 2.15, 2.13 and 3.6eV for the C(46)H(22)N(8)O(4)KFe, C(46)H(22)N(8)O(4)KPb and C(46)H(22)N(8)O(4)KCo thin films.

Breakthrough to Non-Vacuum Deposition of Single-Crystal, Ultra-Thin, Homogeneous Nanoparticle Layers: A Better Alternative to Chemical Bath Deposition and Atomic Layer Deposition

PubMed Central

Liao, Yu-Kuang; Liu, Yung-Tsung; Hsieh, Dan-Hua; Shen, Tien-Lin; Hsieh, Ming-Yang; Tzou, An-Jye; Chen, Shih-Chen; Tsai, Yu-Lin; Lin, Wei-Sheng; Chan, Sheng-Wen; Shen, Yen-Ping; Cheng, Shun-Jen; Chen, Chyong-Hua; Wu, Kaung-Hsiung; Chen, Hao-Ming; Kuo, Shou-Yi; Charlton, Martin D. B.; Hsieh, Tung-Po; Kuo, Hao-Chung

2017-01-01

Most thin-film techniques require a multiple vacuum process, and cannot produce high-coverage continuous thin films with the thickness of a few nanometers on rough surfaces. We present a new ”paradigm shift” non-vacuum process to deposit high-quality, ultra-thin, single-crystal layers of coalesced sulfide nanoparticles (NPs) with controllable thickness down to a few nanometers, based on thermal decomposition. This provides high-coverage, homogeneous thickness, and large-area deposition over a rough surface, with little material loss or liquid chemical waste, and deposition rates of 10 nm/min. This technique can potentially replace conventional thin-film deposition methods, such as atomic layer deposition (ALD) and chemical bath deposition (CBD) as used by the Cu(In,Ga)Se2 (CIGS) thin-film solar cell industry for decades. We demonstrate 32% improvement of CIGS thin-film solar cell efficiency in comparison to reference devices prepared by conventional CBD deposition method by depositing the ZnS NPs buffer layer using the new process. The new ZnS NPs layer allows reduction of an intrinsic ZnO layer, which can lead to severe shunt leakage in case of a CBD buffer layer. This leads to a 65% relative efficiency increase. PMID:28383488

Transparent electrical conducting films by activated reactive evaporation

DOEpatents

Bunshah, R.; Nath, P.

1982-06-22

Process and apparatus for producing transparent electrical conducting thin films by activated reactive evaporation is disclosed. Thin films of low melting point metals and alloys, such as indium oxide and indium oxide doped with tin, are produced by physical vapor deposition. The metal or alloy is vaporized by electrical resistance heating in a vacuum chamber, oxygen and an inert gas such as argon are introduced into the chamber, and vapor and gas are ionized by a beam of low energy electrons in a reaction zone between the resistance heater and the substrate. There is a reaction between the ionized oxygen and the metal vapor resulting in the metal oxide which deposits on the substrate as a thin film which is ready for use without requiring post deposition heat treatment. 1 fig.

Vacuum Arc Vapor Deposition Method and Apparatus for Applying Identification Symbols to Substrates

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor); Roxby, Donald L. (Inventor); Weeks, Jack L. (Inventor)

2002-01-01

An apparatus for applying permanent markings onto products using a Vacuum Arc Vapor Deposition (VAVD) marker by accelerating atoms or molecules from a vaporization source onto a substrate to form human and/or machine-readable part identification marking that can be detected optically or via a sensing device like x-ray, thermal imaging, ultrasound, magneto-optic, micro-power impulse radar, capacitance, or other similar sensing means. The apparatus includes a housing with a nozzle having a marking end. A chamber having an electrode, a vacuum port and a charge is located within the housing. The charge is activated by the electrode in a vacuum environment and deposited onto a substrate at the marking end of the nozzle. The apparatus may be a hand-held device or be disconnected from the handle and mounted to a robot or fixed station.

Highly Controlled Codeposition Rate of Organolead Halide Perovskite by Laser Evaporation Method.

PubMed

Miyadera, Tetsuhiko; Sugita, Takeshi; Tampo, Hitoshi; Matsubara, Koji; Chikamatsu, Masayuki

2016-10-05

Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH 3 NH 3 I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI 2 and CH 3 NH 3 I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

Fabrication and characterization of silver- and copper-coated Nylon 6 forcespun nanofibers by thermal evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mihut, Dorina M., E-mail: dorinamm@yahoo.com; Lozano, Karen; Foltz, Heinrich

2014-11-01

Silver and copper nanoparticles were deposited as thin films onto substrates consisting of Nylon 6 nanofibers manufactured using forcespinning{sup ®} equipment. Different rotational speeds were used to obtain continuous nanofibers of various diameters arranged as nonwoven mats. The Nylon 6 nanofibers were collected as successive layers on frames, and a high-vacuum thermal evaporation method was used to deposit the silver and copper thin films on the nanofibers. The structures were investigated using scanning electron microscopy–scanning transmission electron microscopy, atomic force microscopy, x-ray diffraction, and electrical resistance measurements. The results indicate that evaporated silver and copper nanoparticles were successfully deposited onmore » Nylon 6 nanofibers as thin films that adhered well to the polymer substrate while the native morphology of the nanofibers were preserved, and electrically conductive nanostructures were achieved.« less

Vacuum deposition of iridium on large astronomical mirrors for use in the far UV

NASA Technical Reports Server (NTRS)

Herzig, H.; Spencer, R. S.

1982-01-01

An iridium coating has been deposited by electron-beam evaporation on a 0.91-m mirror which serves as the telescope primary of a sounding rocket instrument for far-UV spectrometry. The evaporation was carried out by applying 8 kV at 400 mA to the electron gun. Zone refined Ir of 99.99% purity was used, and the electron beam was electromagnetically swept over the surface of the evaporant. Under these conditions, deposition rates of 0.55 A/sec were achieved. The reflectance distribution achieved at a wavelength of 584 A was extremely uniform; the mean reflectance was 21.2% with a standard deviation of only 0.3%. This represents a substantial improvement over Al + MgF2 and Al + LiF coatings for applications involving multiple reflections and weak signals, as might be expected in a high-resolution spectrograph studying distant celestial objects.

Lipase biofilm deposited by Matrix Assisted Pulsed Laser Evaporation technique

NASA Astrophysics Data System (ADS)

Aronne, Antonio; Bloisi, Francesco; Calabria, Raffaela; Califano, Valeria; Depero, Laura E.; Fanelli, Esther; Federici, Stefania; Massoli, Patrizio; Vicari, Luciano R. M.

2015-05-01

Lipase is an enzyme that finds application in biodiesel production and for detection of esters and triglycerides in biosensors. Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique derived from Pulsed Laser Deposition (PLD) for deposition of undamaged biomolecules or polymers, is characterized by the use of a frozen target obtained from a solution/suspension of the guest material (to be deposited) in a volatile matrix (solvent). The presence of the solvent avoids or at least reduces the potential damage of guest molecules by laser radiation but only the guest material reaches the substrate in an essentially solvent-free deposition. MAPLE can be used for enzymes immobilization, essential for industrial application, allowing the development of continuous processes, an easier separation of products, the reuse of the catalyst and, in some cases, enhancing enzyme properties (pH, temperature stability, etc.) and catalytic activity in non-aqueous media. Here we show that MAPLE technique can be used to deposit undamaged lipase and that the complex structure (due to droplets generated during extraction from target) of the deposited material can be controlled by changing the laser beam fluence.

Temperature stabilized effusion cell evaporation source for thin film deposition and molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Tiedje, H. F.; Brodie, D. E.

2000-05-01

A simple effusion cell evaporation source for thin film deposition and molecular-beam epitaxy is described. The source consists of a crucible with a thermocouple temperature sensor heated by a resistive crucible heater. Radiation heat transfer from the crucible to the thermocouple produces a consistent and reproducible thermocouple temperature for a given crucible temperature, without direct contact between the thermocouple and the crucible. The thermocouple temperature is somewhat less than the actual crucible temperature because of heat flow from the thermocouple junction along the thermocouple lead wires. In a typical case, the thermocouple temperature is 1007 °C while the crucible is at 1083 °C. The crucible temperature stability is estimated from the measured sensitivity of the evaporation rate of indium to temperature, and the observed variations in the evaporation rate for a fixed thermocouple temperature. The crucible temperature peak-to-peak variation over a one hour period is 1.2 °C. Machined molybdenum crucibles were used in the indium and copper sources for depositing CuInSe2 thin films for solar cells.

Microstructure related properties of gadolinium fluoride films deposited by molybdenum boat evaporation

NASA Astrophysics Data System (ADS)

Chang, Y. H.; Wang, C. Y.; Qi, L. Q.; Liu, H.

2017-08-01

In order to optimize the performance of fluoride thin films in wavelength of Deep Ultraviolet (DUV), GdF3 single layers are prepared by thermal evaporation at different deposition temperatures on Fused Silica. Optical and structure properties of each sample are characterized. The results that the refrac-tive index increased gradually and the crystallization status becomes stronger with the temperature rising, the inhomogeneous of the thin films present linearity. The decrease total optical loss with deposited temper-ature is attributed to the higher packing density and lower optical absorption.

Vapor-crystal phase transition in synthesis of paracetamol films by vacuum evaporation and condensation

NASA Astrophysics Data System (ADS)

Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.; Zarembo, V. I.

2014-03-01

We report on the structural and technological investigations of the vapor-crystal phase transition during synthesis of paracetamol films of the monoclinic system by vacuum evaporation and condensation in the temperature range 220-320 K. The complex nature of the transformation accompanied by the formation of a gel-like phase is revealed. The results are interpreted using a model according to which the vapor-crystal phase transition is not a simple first-order phase transition, but is a nonlinear superposition of two phase transitions: a first-order transition with a change in density and a second-order phase transition with a change in ordering. Micrographs of the surface of the films are obtained at different phases of formation.

Vacuum-deposited, nonpolymeric flexible organic light-emitting devices.

PubMed

Gu, G; Burrows, P E; Venkatesh, S; Forrest, S R; Thompson, M E

1997-02-01

We demonstrate mechanically flexible, organic light-emitting devices (OLED's) based on the nonpolymetric thin-film materials tris-(8-hydroxyquinoline) aluminum (Alq(3)) and N, N(?) -diphenyl- N, N(?) -bis(3-methylphenyl)1- 1(?) biphenyl-4, 4(?) diamine (TPD). The single heterostructure is vacuum deposited upon a transparent, lightweight, thin plastic substrate precoated with a transparent, conducting indium tin oxide thin film. The flexible OLED performance is comparable with that of conventional OLED's deposited upon glass substrates and does not deteriorate after repeated bending. The large-area (~1 - cm>(2)) devices can be bent without failure even after a permanent fold occurs if they are on the convex substrate surface or over a bend radius of ~0.5>cm if they are on the concave surface. Such devices are useful for ultralightweight, flexible, and comfortable full-color flat panel displays.

Comparison of the Al back contact deposited by sputtering, e-beam, or thermal evaporation for inverted perovskite solar cells

NASA Astrophysics Data System (ADS)

Wahl, Tina; Hanisch, Jonas; Ahlswede, Erik

2018-04-01

In this work, we present inverted perovskite solar cells with Al top electrodes, which were deposited by three different methods. Besides the widely used thermal evaporation of Al, we also used the industrially important high deposition rate processes sputtering and electron beam evaporation for aluminium electrodes and examined the influence of the deposition method on the solar cell performance. The current-voltage characteristics of as grown solar cells with sputtered and e-beam Al electrode show an s-shape due to damage done to the organic electronic transport layers (ETL) during Al deposition. It can be cured by a short annealing step at a moderate temperature so that fill factors  >60% and power conversion efficiencies of almost 12% with negligible hysteresis can be achieved. While solar cells with thermally evaporated Al electrode do not show an s-shape, they also exhibit a clear improvement after a short annealing step. In addition, we varied the thickness of the ETL consisting of a double layer ([6,6]-Phenyl-C61-butyric acid methyl ester and bathocuproine) and investigated the influence on the solar cell parameters for the three different Al deposition methods, which showed distinct dependencies on ETL thickness.

Vacuum casting of thick polymeric films

NASA Technical Reports Server (NTRS)

Cuddihy, E. F.; Moacanin, J.

1979-01-01

Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

Thermally evaporated conformal thin films on non-traditional/non-planar substrates

NASA Astrophysics Data System (ADS)

Pulsifer, Drew Patrick

Conformal thin films have a wide variety of uses in the microelectronics, optics, and coatings industries. The ever-increasing capabilities of these conformal thin films have enabled tremendous technological advancement in the last half century. During this period, new thin-film deposition techniques have been developed and refined. While these techniques have remarkable performance for traditional applications which utilize planar substrates such as silicon wafers, they are not suitable for the conformal coating of non-traditional substrates such as biological material. The process of thermally evaporating a material under vacuum conditions is one of the oldest thin-film deposition techniques which is able to produce functional film morphologies. A drawback of thermally evaporated thin films is that they are not intrinsically conformal. To overcome this, while maintaining the advantages of thermal evaporation, a procedure for varying the substrates orientation with respect to the incident vapor flux during deposition was developed immediately prior to the research undertaken for this doctoral dissertation. This process was shown to greatly improve the conformality of thermally evaporated thin films. This development allows for several applications of thermally evaporated conformal thin films on non-planar/non-traditional substrates. Three settings in which to evaluate the improved conformal deposition of thermally evaporated thin films were investigated for this dissertation. In these settings the thin-film morphologies are of different types. In the first setting, a bioreplication approach was used to fabricate artificial visual decoys for the invasive species Agrilus planipennis, commonly known as the emerald ash borer (EAB). The mating behavior of this species involves an overflying EAB male pouncing on an EAB female at rest on an ash leaflet before copulation. The male spots the female on the leaflet by visually detecting the iridescent green color of the

Representative shuttle evaporative heat sink

NASA Technical Reports Server (NTRS)

Hixon, C. W.

1978-01-01

The design, fabrication, and testing of a representative shuttle evaporative heat sink (RSEHS) system which vaporizes an expendable fluid to provide cooling for the shuttle heat transport fluid loop is reported. The optimized RSEHS minimum weight design meets or exceeds the shuttle flash evaporator system requirements. A cold trap which cryo-pumps flash evaporator exhaust water from the CSD vacuum chamber test facility to prevent water contamination of the chamber pumping equipment is also described.

Tubular sublimatory evaporator heat sink

NASA Technical Reports Server (NTRS)

Webbon, B. W. (Inventor)

1977-01-01

An evaporative refrigerator or cooler comprising a bundle of spaced, porous walled tubes closed at one of their ends and vented to a vacuum at the other end is disclosed. The tube bundle is surrounded by a water jacket having a hot water inlet distribution manifold and a cooled water outlet through a plenum chamber. Hot water is pumped into the jacket to circulate around the tubes, and when this water meets the vacuum existing inside the tubes, it evaporates thereby cooling the water in the jacket. If cooling proceeds to the point where water penetrating or surrounding all or part of the tubes freezes, operation continues with local sublimation of the ice on the tubes while the circulating water attempts to melt the ice. Both sublimation and evaporation may take place simultaneously in different regions of the device.

Method of forming ultra thin film devices by vacuum arc vapor deposition

NASA Technical Reports Server (NTRS)

Schramm, Harry F. (Inventor)

2005-01-01

A method for providing an ultra thin electrical circuit integral with a portion of a surface of an object, including using a focal Vacuum Arc Vapor Deposition device having a chamber, a nozzle and a nozzle seal, depressing the nozzle seal against the portion of the object surface to create an airtight compartment in the chamber and depositing one or more ultra thin film layer(s) only on the portion of the surface of the object, the layers being of distinct patterns such that they form the circuit.

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

PubMed Central

Jaramillo, Rafael; Steinmann, Vera; Yang, Chuanxi; Hartman, Katy; Chakraborty, Rupak; Poindexter, Jeremy R.; Castillo, Mariela Lizet; Gordon, Roy; Buonassisi, Tonio

2015-01-01

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices. PMID:26067454

Thermoelectric properties of V2O5 thin films deposited by thermal evaporation

NASA Astrophysics Data System (ADS)

Santos, R.; Loureiro, J.; Nogueira, A.; Elangovan, E.; Pinto, J. V.; Veiga, J. P.; Busani, T.; Fortunato, E.; Martins, R.; Ferreira, I.

2013-10-01

This work reports the structural, optical, electrical and thermoelectric properties of vanadium pentoxide (V2O5) thin films deposited at room temperature by thermal evaporation on Corning glass substrates. A post-deposition thermal treatment up to 973 K under atmospheric conditions induces the crystallization of the as-deposited amorphous films with an orthorhombic V2O5 phase with grain sizes around 26 nm. As the annealing temperature rises up to 773 K the electrical conductivity increases. The films exhibit thermoelectric properties with a maximum Seebeck coefficient of -218 μV/K and electrical conductivity of 5.5 (Ω m)-1. All the films show NIR-Vis optical transmittance above 60% and optical band gap of 2.8 eV.

The structure of deposited metal clusters generated by laser evaporation

NASA Astrophysics Data System (ADS)

Faust, P.; Brandstättner, M.; Ding, A.

1991-09-01

Metal clusters have been produced using a laser evaporation source. A Nd-YAG laser beam focused onto a solid silver rod was used to evaporate the material, which was then cooled to form clusters with the help of a pulsed high pressure He beam. TOF mass spectra of these clusters reveal a strong occurrence of small and medium sized clusters ( n<100). Clusters were also deposited onto grid supported thin layers of carbon-films which were investigated by transmission electron microscopy. Very high resolution pictures of these grids were used to analyze the size distribution and the structure of the deposited clusters. The diffraction pattern caused by crystalline structure of the clusters reveals 3-and 5-fold symmetries as well as fcc bulk structure. This can be explained in terms of icosahedron and cuboctahedron type clusters deposited on the surface of the carbon layer. There is strong evidence that part of these cluster geometries had already been formed before the depostion process. The non-linear dependence of the cluster size and the cluster density on the generating conditions is discussed. Therefore the samples were observed in HREM in the stable DEEKO 100 microscope of the Fritz-Haber-Institut operating at 100 KV with the spherical aberration c S =0.5 mm. The quality of the pictures was improved by using the conditions of minimum phase contrast hollow cone illumination. This procedure led to a minimum of phase contrast artefacts. Among the well-crystallized particles were a great amount of five- and three-fold symmetries, icosahedra and cuboctahedra respectively. The largest clusters with five- and three-fold symmetries have been found with diameters of 7 nm; the smallest particles displaying the same undistorted symmetries were of about 2 mm. Even smaller ones with strong distortions could be observed although their classification is difficult. The quality of the images was improved by applying Fourier filtering techniques.

Effect of thermal annealing on the structural and optical properties of Cu2FeSnS4 thin films grown by vacuum evaporation method

NASA Astrophysics Data System (ADS)

Oueslati, H.; Rabeh, M. Ben; Kanzari, M.

2018-02-01

In this work, the effect of different types of thermal annealing on the properties of Cu2FeSnS4 (CFTS) thin films deposited by thermal evaporation at room temperature on glass substrate were investigated. CFTS powder was synthesized by direct melting of the constituent elements taken in stoichiometry compositions. The X-ray diffraction experimental data indicating that the Cu2FeSnS4 powder illustrating a stannite structure in space group I\\bar {4}2m. From the XRD analysis we have found that the polycrystalline CFTS thin film was only obtained by thermal annealed in sulfur atmosphere under a high vacuum of 400 °C temperature during 2 h. Optical study reveals that the thin films have relatively high absorption coefficients (≈ 105cm-1) and the values of optical band gap energy ranged between 1.38 and 1.48 eV. Other optical parameters were evaluated according to the models of Wemple Di-Domenico and Spitzer-Fan. Finally, hot probe measurements of CFTS thin films reveal p-type conductivity.

Structural and Optical Properties of Cd 1- x Se x Thin Films Deposited by Electron Beam Evaporation Technique

NASA Astrophysics Data System (ADS)

Tripathi, Ravishankar Nath; Verma, Aneet Kumar; Rahul, Vishwakarma, S. R.

2011-10-01

Cadmium selenide (CdSe) thin films deposited by means of electron beam evaporation technique under high vacuum ˜10 -5 torr on ultrasonically cleaned glass substrate. Using stating materials of various compositions of cadmium and selenium using formula Cd 1- x Se x where x is orbitory constant having value 0.20≤ x ≤0.40 here we take less value of x for the creation of anion vacancy in thin films. In present work the structural properties have been studies using XRD technique and found that starting materials and thin films both are polycrystalline in nature having hexagonal structure. Here we study the effect of composition ratio Cd/Se in starting material and its prepared thin films on its grain size and lattice parameter. From the analysis of X-Ray diffractogram found that lattice parameter and grain size both are decreases with increasing Cd/Se ratio in thin films as well as in starting material the preferred orientation in thin films along (100) plane. The surface morphology was studied using SEM characterization and found that films are smooth and homogeneous. The films have been analysed for optical band gap and absorbed a direct band gap.

Electrospray deposition of organic molecules on bulk insulator surfaces.

PubMed

Hinaut, Antoine; Pawlak, Rémy; Meyer, Ernst; Glatzel, Thilo

2015-01-01

Large organic molecules are of important interest for organic-based devices such as hybrid photovoltaics or molecular electronics. Knowing their adsorption geometries and electronic structures allows to design and predict macroscopic device properties. Fundamental investigations in ultra-high vacuum (UHV) are thus mandatory to analyze and engineer processes in this prospects. With increasing size, complexity or chemical reactivity, depositing molecules by thermal evaporation becomes challenging. A recent way to deposit molecules in clean conditions is Electrospray Ionization (ESI). ESI keeps the possibility to work with large molecules, to introduce them in vacuum, and to deposit them on a large variety of surfaces. Here, ESI has been successfully applied to deposit triply fused porphyrin molecules on an insulating KBr(001) surface in UHV environment. Different deposition coverages have been obtained and characterization of the surface by in-situ atomic force microscopy working in the non-contact mode shows details of the molecular structures adsorbed on the surface. We show that UHV-ESI, can be performed on insulating surfaces in the sub-monolayer regime and to single molecules which opens the possibility to study a variety of complex molecules.

Current-voltage characteristics of organic photovoltaic cells following deposition of cathode electrode

PubMed Central

Saeki, Hiroyuki; Hirohara, Kazuto; Koshiba, Yasuko; Horie, Satoshi; Misaki, Masahiro; Takeshita, Kimiya; Ishida, Kenji; Ueda, Yasukiyo

2010-01-01

The current-voltage characteristics of benzoporphine-fullerene solar cells were measured subsequent to the deposition of Al as a cathode material. Even in vacuum, a shift in the open circuit voltage was observed at 20 min after Al deposition. Moreover, the displacement of inert gases (N2or Ar) in the evaporation chamber enhanced the photovoltaic parameters. The power conversion efficiency was increased by 24% over the initial characteristics (from 1.04% to 1.29%), which indicates that the structure of the organic-metal interface changed rapidly after Al deposition, even if the process was performed in an air-free glovebox. PMID:21151322

Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemberg, Axel; Dauchot, Jean-Pierre; Snyders, Rony

2012-07-15

The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

Normal evaporation of binary alloys

NASA Technical Reports Server (NTRS)

Li, C. H.

1972-01-01

In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

Study the Effect of Substrate Temperature on Structural and Electrical Properties of Electron Beam Evaporated In{sub 1−x}Sb{sub x} Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahul, E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com; Vishwakarma, S. R., E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com; Verma, Aneet Kumar, E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com

2011-10-20

Indium Antimonide (InSb) is a promising materials for mid and long wavelength infrared and high speed devices applications because of its small band gap. The Indium Antimonide (InSb) thin films have been deposited onto well cleaned glass substrate at different substrate temperatures (300 K, 323 K, 373 K) by electron beam evaporation technique in the high vacuum chamber at vacuum pressure ∼10{sup −5} torr using prepared non‐stoichiometric InSb powder using formula In{sub 1−x}Sb{sub x}(0.2

Butanol production from lignocellulose by simultaneous fermentation, saccharification, and pervaporation or vacuum evaporation.

PubMed

Díaz, Víctor Hugo Grisales; Tost, Gerard Olivar

2016-10-01

Techno-economic study of acetone, butanol and ethanol (ABE) fermentation from lignocellulose was performed. Simultaneous saccharification, fermentation and vacuum evaporation (SFS-V) or pervaporation (SFS-P) were proposed. A kinetic model of metabolic pathways for ABE fermentation with the effect of phenolics and furans in the growth was proposed based on published laboratory results. The processes were optimized in Matlab®. The end ABE purification was carried out by heat-integrated distillation. The objective function of the minimization was the total annualized cost (TAC). Fuel consumption of SFS-P using poly[1-(trimethylsilyl)-1-propyne] membrane was between 13.8 and 19.6% lower than SFS-V. Recovery of furans and phenolics for the hybrid reactors was difficult for its high boiling point. TAC of SFS-P was increased 1.9 times with supplementation of phenolics and furans to 3g/l each one for its high toxicity. Therefore, an additional detoxification method or an efficient pretreatment process will be necessary. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Safe and Efficient Evaporation of a Solvent from Solution

NASA Astrophysics Data System (ADS)

Mahon, Andrew R.

1997-02-01

The process of evaporating a solvent from a solution can cause problems for many students. By using a water-vacuum aspirator, backflashes of water can flood the sample tube and be detrimental to the experiment. This type of apparatus can also cause problems by drawing the solution it is evaporating back into the vacuum hose, causing the student to lose part or all of the products of their experiment. Macroscale and Microscale Organic Experiments, 2nd edition (1), suggested two techniques to dissolve solvents from a mixture. It suggested blowing a stream of air over the solution from a Pasteur pipet, or attaching a Pasteur pipet to an aspirator and drawing air over the surface of the liquid. Again, the danger of blowing air over the solution leaves the risk of splattering the solution, and drawing air over the surface of the liquid as described further endangers the products of the experiment through the risk of sucking the products up into the pipet aspirator. In an effort to eliminate these problems, a new technique has been developed. By inverting an ordinary 200-mL vacuum flask and pulling a steady current of air from the vacuum apparatus through it, any type of small container can be placed under it, allowing the solvent to be evaporated in a steady, mistake-free manner . By evaporating the solvent from the container that the products will be submitted in, no sample is lost through the process of transferring it from a vacuum flask or beaker to the final container.

Comparative analysis of electrophysical properties of ceramic tantalum pentoxide coatings, deposited by electron beam evaporation and magnetron sputtering methods

NASA Astrophysics Data System (ADS)

Donkov, N.; Mateev, E.; Safonov, V.; Zykova, A.; Yakovin, S.; Kolesnikov, D.; Sudzhanskaya, I.; Goncharov, I.; Georgieva, V.

2014-12-01

Ta2O5 ceramic coatings have been deposited on glass substrates by e-beam evaporation and magnetron sputtering methods. For the magnetron sputtering process Ta target was used. X-ray diffraction measurements show that these coatings are amorphous. XPS survey spectra of the ceramic Ta2O5 coatings were obtained. All spectra consist of well-defined XPS lines of Ta 4f, 4d, 4p and 4s; O 1s; C 1s. Ta 4f doublets are typical for Ta2O5 coatings with two main peaks. Scanning electron microscopy and atomic force microscopy images of the e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have revealed a relatively flat surface with no cracks. The dielectric properties of the tantalum pentoxide coatings have been investigated in the frequency range of 100 Hz to 1 MHz. The electrical behaviour of e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have also been compared. The deposition process conditions principally effect the structure parameters and electrical properties of Ta2O5 ceramic coatings. The coatings deposited by different methods demonstrate the range of dielectric parameters due to the structural and stoichiometric composition changes

Comparison of the columnar-thin-film and vacuum-metal-deposition techniques to develop sebaceous fingermarks on nonporous substrates.

PubMed

Williams, Stephanie F; Pulsifer, Drew P; Shaler, Robert C; Ramotowski, Robert S; Brazelle, Shelly; Lakhtakia, Akhlesh

2015-03-01

Both the columnar-thin-film (CTF) and the vacuum-metal-deposition (VMD) techniques for visualizing sebaceous fingermarks require the deposition of a material thereon in a vacuum chamber. Despite that similarity, there are many differences between the two techniques. The film deposited with the CTF technique has a columnar morphology, but the film deposited with the VMD technique comprises discrete islands. A split-print methodology on a variety of fingermarked substrates was used to determine that the CTF technique is superior for developing fingermarks on clear sandwich bags and partial bloody fingermarks on stainless steel. Both techniques are similar in their ability to develop fingermarks on glass but the CTF technique yields higher contrast. The VMD technique is superior for developing fingermarks on white grocery bags and the smooth side of Gloss Finish Scotch Multitask(™) tape. Neither technique worked well for fingermarks on black garbage bags. © 2014 American Academy of Forensic Sciences.

Realization of single-phase BaSi2 films by vacuum evaporation with suitable optical properties and carrier lifetime for solar cell applications

NASA Astrophysics Data System (ADS)

Hara, Kosuke O.; Nakagawa, Yoshihiko; Suemasu, Takashi; Usami, Noritaka

2015-07-01

We have realized BaSi2 films by a simple vacuum evaporation technique for solar cell applications. X-ray diffraction analysis shows that single-phase BaSi2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrates or at a substrate temperature of 400 °C. The mechanism of film growth is discussed by analyzing the residue on the evaporation boat. An issue on the fabricated films is cracking due to thermal mismatch, as observed by secondary electron microscopy. Optical characterizations by transmittance and reflectance spectroscopy show that the evaporated films have high absorption coefficients, reaching 2 × 104 cm-1 for a photon energy of 1.5 eV, and have indirect absorption edges of 1.14-1.21 eV, which are suitable for solar cells. The microwave-detected photoconductivity decay measurement reveals that the carrier lifetime is approximately 0.027 µs, corresponding to the diffusion length of 0.84 µm, which suggests the potential effective usage of photoexcited carriers.

Analysis of the aging/stability process of organic solar cells based on PTB7:[70]PCBM and an alternative free-vacuum deposited cathode: the effect of active layer scaling

NASA Astrophysics Data System (ADS)

Barreiro-Argüelles, Denisse; Ramos-Ortiz, Gabriel; Maldonado, José-Luis L.; Romero-Borja, Daniel; Meneses-Nava, Marco-Antonio; Pérez-Gutiérrez, Enrique

2017-08-01

The PV performance and aging/stability of organic photovoltaic (OPV) devices based on the well-known system PTB7:[70]PCBM and an alternative air-stable electrode deposited at room conditions are fully studied when the active area is scaled by a factor of 25. On the other hand, the aging/stability processes were also studied through single diode model, impedance spectroscopy and light-beam induced current (LBIC) measurements in accordance with the established ISOS-D1 (dark storage) and ISOS-L1 (illumination conditions) protocols. Results are a good indication that the alternative cathode Field's metal (FM) cathode works as an encapsulating material and provides excellent PV performance comparable with the common and costly high-vacuum evaporated Al cathode.

The influence of gravity on the distribution of the deposit formed onto a substrate by sessile, hanging, and sandwiched hanging drop evaporation.

PubMed

Sandu, Ion; Fleaca, Claudiu Teodor

2011-06-15

The focus of the present article is the study of the influence of gravity on the particle deposition profiles on a solid substrate during the evaporation of sessile, hanging and sandwiched hanging drops of colloidal particle suspensions. For concentrations of nanoparticles in the colloidal solutions in the range 0.0001-1 wt.%, highly diluted suspensions will preferentially form rings while concentrated suspensions will preferentially form spots in both sessile and hanging drop evaporation. For intermediary concentrations, the particle deposition profiles will depend on the nanoparticle aggregation dynamics in the suspension during the evaporation process, gravity and on the detailed evaporation geometry. The evaporation of a drop of toluene/carbon nanoparticle suspension hanging from a pendant water drop will leave on the substrate a circular spot with no visible external ring. By contrast, a clear external ring is formed on the substrate by the sessile evaporation of a similar drop of suspension sandwiched between a water drop and the substrate. From the application viewpoint, these processes can be used to create preferential electrical conductive carbon networks and contacts for arrays of self-assembled nanostructures fabricated on solid substrates as well as on flexible polymeric substrates. Copyright © 2011 Elsevier Inc. All rights reserved.

Sheet Membrane Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

2013-01-01

A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

Hydroxyapatite thin films grown by pulsed laser deposition and matrix assisted pulsed laser evaporation: Comparative study

NASA Astrophysics Data System (ADS)

Popescu-Pelin, G.; Sima, F.; Sima, L. E.; Mihailescu, C. N.; Luculescu, C.; Iordache, I.; Socol, M.; Socol, G.; Mihailescu, I. N.

2017-10-01

Pulsed Laser Deposition (PLD) and Matrix Assisted Pulsed Laser Evaporation (MAPLE) techniques were applied for growing hydroxyapatite (HA) thin films on titanium substrates. All experiments were conducted in a reaction chamber using a KrF* excimer laser source (λ = 248 nm, τFWHM ≈ 25 ns). Half of the samples were post-deposition thermally treated at 500 °C in a flux of water vapours in order to restore crystallinity and improve adherence. Coating surface morphologies and topographies specific to the deposition method were evidenced by scanning electron, atomic force microscopy investigations and profilometry. They were shown to depend on deposition technique and also on the post-deposition treatment. Crystalline structure of the coatings evaluated by X-ray diffraction was improved after thermal treatment. Biocompatibility of coatings, cellular adhesion, proliferation and differentiation tests were conducted using human mesenchymal stem cells (MSCs). Results showed that annealed MAPLE deposited HA coatings were supporting MSCs proliferation, while annealed PLD obtained films were stimulating osteogenic differentiation.

Depth Profiling Analysis of Aluminum Oxidation During Film Deposition in a Conventional High Vacuum System

NASA Technical Reports Server (NTRS)

Kim, Jongmin; Weimer, Jeffrey J.; Zukic, Muamer; Torr, Douglas G.

1994-01-01

The oxidation of aluminum thin films deposited in a conventional high vacuum chamber has been investigated using x-ray photoelectron spectroscopy (XPS) and depth profiling. The state of the Al layer was preserved by coating it with a protective MgF2 layer in the deposition chamber. Oxygen concentrations in the film layers were determined as a function of sputter time (depth into the film). The results show that an oxidized layer is formed at the start of Al deposition and that a less extensively oxidized Al layer is deposited if the deposition rate is fast. The top surface of the Al layer oxidizes very quickly. This top oxidized layer may be thicker than has been previously reported by optical methods. Maximum oxygen concentrations measured by XPS at each Al interface are related to pressure to rate ratios determined during the Al layer deposition.

Characterization of ethylcellulose and hydroxypropyl methylcellulose thin films deposited by matrix-assisted pulsed laser evaporation

NASA Astrophysics Data System (ADS)

Palla-Papavlu, A.; Rusen, L.; Dinca, V.; Filipescu, M.; Lippert, T.; Dinescu, M.

2014-05-01

In this study is reported the deposition of hydroxypropyl methylcellulose (HPMC) and ethylcellulose (EC) by matrix-assisted pulsed laser evaporation (MAPLE). Both HPMC and EC were deposited on silicon substrates using a Nd:YAG laser (266 nm, 5 ns laser pulse and 10 Hz repetition rate) and then characterized by atomic force microscopy and Fourier transform infrared spectroscopy. It was found that for laser fluences up to 450 mJ/cm2 the structure of the deposited HPMC and EC polymer in the thin film resembles to the bulk. Morphological investigations reveal island features on the surface of the EC thin films, and pores onto the HPMC polymer films. The obtained results indicate that MAPLE may be an alternative technique for the fabrication of new systems with desired drug release profile.

Influence of multi-depositions on the final properties of thermally evaporated TlBr films

NASA Astrophysics Data System (ADS)

Destefano, N.; Mulato, M.

2010-12-01

Thallium bromide is a promising candidate material for photodetectors in medical imaging systems. This work investigates the structural, optical and electrical properties of thermally evaporated TlBr films. The main fabrication parameter is the number of depositions. The use of sequential runs is aimed to increase the thickness of the films, as necessary, for technological applications. We deposited films using one-four runs, that led to maximum thickness of about 50 μm. Crystallographic and morphological changes were observed with varying deposition runs. Nevertheless, the optical gap and electrical resistivity in the dark remained constant at about 2.85 eV and 10 9 Ω cm, respectively. Thicker samples have a larger ratio of photo-to-dark signal under medical X-ray exposure, with a larger linear region as a function of applied voltage. The results are discussed aiming at future technological applications in medical imaging.

Characterization and Evaluation of Ti-Zr-V Non-evaporable Getter Films Used in Vacuum Systems

NASA Astrophysics Data System (ADS)

Ferreira, M. J.; Seraphim, R. M.; Ramirez, A. J.; Tabacniks, M. H.; Nascente, P. A. P.

Among several methods used to obtain ultra-high vacuum (UHV) for particles accelerators chambers, it stands out the internal coating with metallic films capable of absorbing gases, called NEG (non-evaporable getter). Usually these materials are constituted by elements of great chemical reactivity and solubility (such as Ti, Zr, and V), at room temperature for oxygen and other gases typically found in UHV, such as H2, CO, and CO2. Gold and ternary Ti-Zr-V films were produced by magnetron sputtering, and their composition, structure, morphology, and aging characteristics were characterized by energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission gun sc anning electronmicroscopy (FEG-SEM), atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM). The comparison between the produced films and commercial samples indicated that the desirable characteristics depend on the nanometric structure of the films and that this structure is sensitive to the heat treatments.

Preparation of Y-Ba-Cu oxide superconductor thin films using pulsed laser evaporation from high T/sub c/ bulk material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dijkkamp, D.; Venkatesan, T.; Wu, X.D.

We report the first successful preparation of thin films of Y-Ba-Cu-O superconductors using pulsed excimer laser evaporation of a single bulk material target in vacuum. Rutherford backscattering spectrometry showed the composition of these films to be close to that of the bulk material. Growth rates were typically 0.1 nm per laser shot. After an annealing treatment in oxygen the films exhibited superconductivity with an onset at 95 K and zero resistance at 85 and 75 K on SrTiO/sub 3/ and Al/sub 2/O/sub 3/ substrates, respectively. This new deposition method is relatively simple, very versatile, and does not require the usemore » of ultrahigh vacuum techniques.« less

Physical Vapor Deposition of Thin Films

NASA Astrophysics Data System (ADS)

Mahan, John E.

2000-01-01

A unified treatment of the theories, data, and technologies underlying physical vapor deposition methods With electronic, optical, and magnetic coating technologies increasingly dominating manufacturing in the high-tech industries, there is a growing need for expertise in physical vapor deposition of thin films. This important new work provides researchers and engineers in this field with the information they need to tackle thin film processes in the real world. Presenting a cohesive, thoroughly developed treatment of both fundamental and applied topics, Physical Vapor Deposition of Thin Films incorporates many critical results from across the literature as it imparts a working knowledge of a variety of present-day techniques. Numerous worked examples, extensive references, and more than 100 illustrations and photographs accompany coverage of: * Thermal evaporation, sputtering, and pulsed laser deposition techniques * Key theories and phenomena, including the kinetic theory of gases, adsorption and condensation, high-vacuum pumping dynamics, and sputtering discharges * Trends in sputter yield data and a new simplified collisional model of sputter yield for pure element targets * Quantitative models for film deposition rate, thickness profiles, and thermalization of the sputtered beam

Dynamically controlled deposition of colloidal nanoparticle suspension in evaporating drops using laser radiation.

PubMed

Ta, V D; Carter, R M; Esenturk, E; Connaughton, C; Wasley, T J; Li, J; Kay, R W; Stringer, J; Smith, P J; Shephard, J D

2016-05-18

Dynamic control of the distribution of polystyrene suspended nanoparticles in evaporating droplets is investigated using a 2.9 μm high power laser. Under laser radiation a droplet is locally heated and fluid flows are induced that overcome the capillary flow, and thus a reversal of the coffee-stain effect is observed. Suspension particles are accumulated in a localised area, one order of magnitude smaller than the original droplet size. By scanning the laser beam over the droplet, particles can be deposited in an arbitrary pattern. This finding raises the possibility for direct laser writing of suspended particles through a liquid layer. Furthermore, a highly uniform coating is possible by manipulating the laser beam diameter and exposure time. The effect is expected to be universally applicable to aqueous solutions independent of solutes (either particles or molecules) and deposited substrates.

Hydrogenation behavior of Ti-implanted Zr-1Nb alloy with TiN films deposited using filtered vacuum arc and magnetron sputtering

NASA Astrophysics Data System (ADS)

Kashkarov, E. B.; Nikitenkov, N. N.; Sutygina, A. N.; Bezmaternykh, A. O.; Kudiiarov, V. N.; Syrtanov, M. S.; Pryamushko, T. S.

2018-02-01

More than 60 years of operation of water-cooled reactors have shown that local or general critical hydrogen concentration is one of the basic limiting criteria of zirconium-based fuel element claddings. During the coolant radiolysis, released hydrogen penetrates and accumulates in zirconium alloys. Hydrogenation of zirconium alloys leads to degradation of their mechanical properties, hydride cracking and stress corrosion cracking. In this research the effect of titanium nitride (TiN) deposition on hydrogenation behavior of Ti-implanted Zr-1Nb alloy was described. Ti-implanted interlayer was fabricated by plasma immersion ion implantation (PIII) at the pulsed bias voltage of 1500 V to improve the adhesion of TiN and reduce hydrogen penetration into Zr-1Nb alloy. We conducted the comparative analysis on hydrogenation behavior of the Ti-implanted alloy with sputtered and evaporated TiN films by reactive dc magnetron sputtering (dcMS) and filtered cathodic vacuum arc deposition (FVAD), respectively. The crystalline structure and surface morphology were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The elemental distribution was analyzed using glow-discharge optical emission spectroscopy (GD-OES). Hydrogenation was performed from gas atmosphere at 350 °C and 2 atm hydrogen pressure. The results revealed that TiN films as well as Ti implantation significantly reduce hydrogen absorption rate of Zr-1Nb alloy. The best performance to reduce the rate of hydrogen absorption is Ti-implanted layer with evaporated TiN film. Morphology of the films impacted hydrogen permeation through TiN films: the denser film the lower hydrogen permeation. The Ti-implanted interface plays an important role of hydrogen accumulation layer for trapping the penetrated hydrogen. No deterioration of adhesive properties of TiN films on Zr-1Nb alloy with Ti-implanted interface occurs under high-temperature hydrogen exposure. Thus, the fabrication of Ti

Implementation of new integrated evaporation equipment for the preparation of 238U targets and improvement of the deposition process

NASA Astrophysics Data System (ADS)

Vanleeuw, D.; Lewis, D.; Moens, A.; Sibbens, G.; Wiss, T.

2018-05-01

Measurement of neutron cross section data is a core activity of the JRC-Directorate G for Nuclear Safety and Security in Geel. After a period of reduced activity and in line with a renewed interest for nuclear data required for GenIV reactors and waste minimization, the demand for high quality actinide targets increased. Physical vapour deposition by thermal evaporation is a key technique to prepare homogeneous thin actinide layers, but due to ageing effects the earlier in-house developed equipment can no longer provide the required quality. Because of a current lack of experience and human resources cooperation with private companies is required for the development of new deposition equipment directly integrated in a glove box. In this paper we describe the design, implementation and validation of the first commercial actinide evaporator in a glove box as well as the optimization of the deposition process. Highly enriched 238U3O8 was converted to 238UF4 powder and several deposition runs were performed on different substrates. The deposition parameters were varied and defined in order to guarantee physical and chemical stable homogeneous UF4 layers, even on polished substrates which was not longer feasible with the older equipment. The stability problem is discussed in view of the thin layer growth by physical vapour deposition and the influence of the deposition parameters on the layer quality. The deposits were characterized for the total mass by means of substitution weighing and for the areal density of 238U by means of alpha particle counting and thermal ionization mass spectrometry (TIMS). The quality of the layer was visually evaluated and by means of stereo microscopy and auto radiography.

Study of nanostructure and ethanol vapor sensing performance of WO3 thin films deposited by e-beam evaporation method under different deposition angles: application in breath analysis devices

NASA Astrophysics Data System (ADS)

Amani, E.; Khojier, K.; Zoriasatain, S.

2018-01-01

This paper studies the effect of deposition angle on the crystallographic structure, surface morphology, porosity and subsequently ethanol vapor sensing performance of e-beam-evaporated WO3 thin films. The WO3 thin films were deposited by e-beam evaporation technique on SiO2/Si substrates under different deposition angles (0°, 30°, and 60°) and then post-annealed at 500 °C with a flow of oxygen for 4 h. Crystallographic structure and surface morphology of the samples were checked using X-ray diffraction method and atomic force microscopy, respectively. Physical adsorption isotherm was also used to measure the porosity and effective surface area of the samples. The electrical response of the samples was studied to different concentrations of ethanol vapor (10-50 ppm) at the temperature range of 140-260 °C and relative humidity of 80%. The results reveal that the WO3 thin film deposited under 30° angle shows more sensitivity to ethanol vapor than the other samples prepared in this work due to the more crystallinity, porosity, and effective surface area. The investigations also show that the sample deposited at 30° can be a good candidate as a breath analysis device at the operating temperature of 240 °C because of its high response, low detection limit, and reliability at high relative humidity.

Lysozyme pattern formation in evaporating droplets

NASA Astrophysics Data System (ADS)

Gorr, Heather Meloy

Liquid droplets containing suspended particles deposited on a solid, flat surface generally form ring-like structures due to the redistribution of solute during evaporation (the "coffee ring effect"). The forms of the deposited patterns depend on complex interactions between solute(s), solvent, and substrate in a rapidly changing, far from equilibrium system. Solute self-organization during evaporation of colloidal sessile droplets has attracted the attention of researchers over the past few decades due to a variety of technological applications. Recently, pattern formation during evaporation of various biofluids has been studied due to potential applications in medical screening and diagnosis. Due to the complexity of 'real' biological fluids and other multicomponent systems, a comprehensive understanding of pattern formation during droplet evaporation of these fluids is lacking. In this PhD dissertation, the morphology of the patterns remaining after evaporation of droplets of a simplified model biological fluid (aqueous lysozyme solutions + NaCl) are examined by atomic force microscopy (AFM) and optical microscopy. Lysozyme is a globular protein found in high concentration, for example, in human tears and saliva. The drop diameters, D, studied range from the micro- to the macro- scale (1 microm -- 2 mm). In this work, the effect of evaporation conditions, solution chemistry, and heat transfer within the droplet on pattern formation is examined. In micro-scale deposits of aqueous lysozyme solutions (1 microm < D < 50 microm), the protein motion and the resulting dried residue morphology are highly influenced by the decreased evaporation time of the drop. The effect of electrolytes on pattern formation is also investigated by adding varying concentrations NaCl to the lysozyme solutions. Finally, a novel pattern recognition program is described and implemented which classifies deposit images by their solution chemistries. The results presented in this Ph

Organic Thin Films Deposited by Emulsion-Based, Resonant Infrared, Matrix-Assisted Pulsed Laser Evaporation: Fundamentals and Applications

NASA Astrophysics Data System (ADS)

Ge, Wangyao

Thin film deposition techniques are indispensable to the development of modern technologies as thin film based optical coatings, optoelectronic devices, sensors, and biological implants are the building blocks of many complicated technologies, and their performance heavily depends on the applied deposition technique. Particularly, the emergence of novel solution-processed materials, such as soft organic molecules, inorganic compounds and colloidal nanoparticles, facilitates the development of flexible and printed electronics that are inexpensive, light weight, green and smart, and these thin film devices represent future trends for new technologies. One appealing feature of solution-processed materials is that they can be deposited into thin films using solution-processed deposition techniques that are straightforward, inexpensive, high throughput and advantageous to industrialize thin film based devices. However, solution-processed techniques rely on wet deposition, which has limitations in certain applications, such as multi-layered film deposition of similar materials and blended film deposition of dissimilar materials. These limitations cannot be addressed by traditional, vacuum-based deposition techniques because these dry approaches are often too energetic and can degrade soft materials, such as polymers, such that the performance of resulting thin film based devices is compromised. The work presented in this dissertation explores a novel thin film deposition technique, namely emulsion-based, resonant infrared, matrix-assisted pulsed laser evaporation (RIR-MAPLE), which combines characteristics of wet and dry deposition techniques for solution-processed materials. Previous studies have demonstrated the feasibility of emulsion-based RIR-MAPLE to deposit uniform and continuous organic, nanoparticle and blended films, as well as hetero-structures that otherwise are difficult to achieve. However, fundamental understanding of the growth mechanisms that govern

Filtered cathodic arc deposition apparatus and method

DOEpatents

Krauss, Alan R.

1999-01-01

A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

Evaluation of evaporation coefficient for micro-droplets exposed to low pressure: A semi-analytical approach

NASA Astrophysics Data System (ADS)

Chakraborty, Prodyut R.; Hiremath, Kirankumar R.; Sharma, Manvendra

2017-02-01

Evaporation rate of water is strongly influenced by energy barrier due to molecular collision and heat transfer limitations. The evaporation coefficient, defined as the ratio of experimentally measured evaporation rate to that maximum possible theoretical limit, varies over a conflicting three orders of magnitude. In the present work, a semi-analytical transient heat diffusion model of droplet evaporation is developed considering the effect of change in droplet size due to evaporation from its surface, when the droplet is injected into vacuum. Negligible effect of droplet size reduction due to evaporation on cooling rate is found to be true. However, the evaporation coefficient is found to approach theoretical limit of unity, when the droplet radius is less than that of mean free path of vapor molecules on droplet surface contrary to the reported theoretical predictions. Evaporation coefficient was found to reduce rapidly when the droplet under consideration has a radius larger than the mean free path of evaporating molecules, confirming the molecular collision barrier to evaporation rate. The trend of change in evaporation coefficient with increasing droplet size predicted by the proposed model will facilitate obtaining functional relation of evaporation coefficient with droplet size, and can be used for benchmarking the interaction between multiple droplets during evaporation in vacuum.

Dielectric properties of Ba0.6Sr0.4TiO3 thin films deposited by mist plasma evaporation using aqueous solution precursor

NASA Astrophysics Data System (ADS)

Huang, Hui; Shi, Peng; Wang, Minqiang; Yao, Xi; Tan, O. K.

2006-06-01

Mist plasma evaporation (MPE) technique has been developed to deposit Ba0.6Sr0.4TiO3 (BST) thin films on SiO2/Si and Pt/Ti/SiO2/Si substrates at atmospheric pressure using metal nitrate aqueous solution as precursor. MPE is characterized by the injection of liquid reactants into thermal plasma where the source materials in the droplets are evaporated by the high temperature of the thermal plasma. Nanometer-scale clusters are formed in the tail flame of the plasma, and then deposited and rearranged on the substrate at a lower temperature. Due to the high temperature annealing process of the thermal plasma before deposition, well-crystallized BST films were deposited at substrate temperature of 630 °C. The dielectric constant and dielectric loss of the film at 100 kHz are 715 and 0.24, respectively. Due to the good crystallinity of the BST films deposited by MPE, high dielectric tunability up to 39.3% is achieved at low applied electric field of 100 kV cm-1.

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwindt, Peter D. D., E-mail: pschwin@sandia.gov; Jau, Yuan-Yu; Partner, Heather

2016-05-15

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm{sup 3} in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it wasmore » sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of {sup 171}Y b{sup +}. The fractional frequency stability of the clock was measured to be 2 × 10{sup −11}/τ{sup 1/2}.« less

A highly miniaturized vacuum package for a trapped ion atomic clock

DOE PAGES

Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; ...

2016-05-12

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm 3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, the packagemore » was sealed with a copper pinch-off and was then pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Yb +. The fractional frequency stability of the clock was measured to be 2 × 10 -11 / τ 1/2.« less

Synaptic organic transistors with a vacuum-deposited charge-trapping nanosheet

PubMed Central

Kim, Chang-Hyun; Sung, Sujin; Yoon, Myung-Han

2016-01-01

Organic neuromorphic devices hold great promise for unconventional signal processing and efficient human-machine interfaces. Herein, we propose novel synaptic organic transistors devised to overcome the traditional trade-off between channel conductance and memory performance. A vacuum-processed, nanoscale metallic interlayer provides an ultra-flat surface for a high-mobility molecular film as well as a desirable degree of charge trapping, allowing for low-temperature fabrication of uniform device arrays on plastic. The device architecture is implemented by widely available electronic materials in combination with conventional deposition methods. Therefore, our results are expected to generate broader interests in incorporation of organic electronics into large-area neuromorphic systems, with potential in gate-addressable complex logic circuits and transparent multifunctional interfaces receiving direct optical and cellular stimulation. PMID:27645425

Synaptic organic transistors with a vacuum-deposited charge-trapping nanosheet

NASA Astrophysics Data System (ADS)

Kim, Chang-Hyun; Sung, Sujin; Yoon, Myung-Han

2016-09-01

Organic neuromorphic devices hold great promise for unconventional signal processing and efficient human-machine interfaces. Herein, we propose novel synaptic organic transistors devised to overcome the traditional trade-off between channel conductance and memory performance. A vacuum-processed, nanoscale metallic interlayer provides an ultra-flat surface for a high-mobility molecular film as well as a desirable degree of charge trapping, allowing for low-temperature fabrication of uniform device arrays on plastic. The device architecture is implemented by widely available electronic materials in combination with conventional deposition methods. Therefore, our results are expected to generate broader interests in incorporation of organic electronics into large-area neuromorphic systems, with potential in gate-addressable complex logic circuits and transparent multifunctional interfaces receiving direct optical and cellular stimulation.

Purfication kinetics of beryllium during vacuum induction melting

NASA Technical Reports Server (NTRS)

Mukherjee, J. L.; Gupta, K. P.; Li, C. H.

1972-01-01

The kinetics of evaporation in binary alloys were quantitatively treated. The formalism so developed works well for several systems studied. The kinetics of purification of beryllium was studied through evaporation data actually acquired during vacuum induction melting. Normal evaporation equations are shown to be generally valid and useful for understanding the kinetics of beryllium purification. The normal evaporation analysis has been extended to cover cases of limited liquid diffusion. It was shown that under steady-state evaporation, the solute concentration near the surface may be up to six orders of magnitude different from the bulk concentration. Corrections for limited liquid diffusion are definitely needed for the highly evaporative solute elements, such as Zn, Mg, and Na, for which the computed evaporation times are improved by five orders of magnitude. The commonly observed logarithmic relation between evaporation time and final concentration further supports the validity of the normal evaporation equations.

ZnS thin films deposition by thermal evaporation for photovoltaic applications

NASA Astrophysics Data System (ADS)

Benyahia, K.; Benhaya, A.; Aida, M. S.

2015-10-01

ZnS thin films were deposited on glass substrates by thermal evaporation from millimetric crystals of ZnS. The structural, compositional and optical properties of the films are studied by X-ray diffraction, SEM microscopy, and UV-VIS spectroscopy. The obtained results show that the films are pin hole free and have a cubic zinc blend structure with (111) preferential orientation. The estimated optical band gap is 3.5 eV and the refractive index in the visible wavelength ranges from 2.5 to 1.8. The good cubic structure obtained for thin layers enabled us to conclude that the prepared ZnS films may have application as buffer layer in replacement of the harmful CdS in CIGS thin film solar cells or as an antireflection coating in silicon-based solar cells.

Dependence of Magnetic Properties of Co/Pt Multilayers on Deposition Temperature of Pt Buffer Layers

NASA Astrophysics Data System (ADS)

Shiomi, Shigeru; Nishimura, Tomotaka; Kobayashi, Tadashi; Masuda, Morio

1993-04-01

A 15-nm-thick Pt buffer layer was deposited on a glass slide at temperature Ts(Ptbuf) ranging from 30 to 300°C by e-gun evaporation. Following the cooling in vacuum to ambient temperature, Co and Pt layers have been alternately deposited on it. Very large perpendicular anisotropy and coercivity have been obtained at Ts(Ptbuf) higher than 200°C. The (111) preferred orientation of the Co/Pt multilayer as well as the Pt buffer layer became more pronounced with elevating Ts(Ptbuf), to which the enhancement of perpendicular anisotropy with elevating Ts(Ptbuf) might be ascribable.

Vacuum testing of high efficiency AMTEC cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuller, M.; Phillips, P.H.; Sievers, R.

1996-12-31

The Phillips Laboratory Power and Thermal Management Division (PL/VTP), in cooperation with JPL, AMPS, Creare, and ORION, is performing vacuum testing of high performance Alkali Metal Thermal to Electric Conversion (AMTEC) cells, including the Micro-Machined Evaporator (MME) and PL-9A cells. The MME cell was designed to test an improved evaporator, which should allow long term operation at evaporator temperatures as high as 1,100 K. The PL-9A cell was designed and built by AMPS under contract to ORION to test an improved heat shield assembly. The testing at Phillips Lab is done in a vacuum test stand which simulates the environmentmore » of an AMTEC cell operating as part of a spacecraft power system. The test configuration consists of the MME cell (later replaced by by the PL-9A cell) in the center of an array of six other AMTEC cells. The seven cells are encased in multifoil insulation. Testing shows that there is little difference between cell current/voltage performance when measured in vacuum tests compared to guard heater tests. The author are also examining the differences between fast I-V curve sweeps, recorded manually, with the cell operating at constant heat input, over a period of five minutes or less, and equilibrium I-V curve sweeps, in which the cell reaches thermal equilibrium at each data point.« less

Structural, morphological, gas sensing and photocatalytic characterization of MoO3 and WO3 thin films prepared by the thermal vacuum evaporation technique

NASA Astrophysics Data System (ADS)

Arfaoui, A.; Touihri, S.; Mhamdi, A.; Labidi, A.; Manoubi, T.

2015-12-01

Thin films of molybdenum trioxide and tungsten trioxide were deposited on glass substrates using a simplified thermal evaporation under vacuum method monitored by heat treatment in flowing oxygen at 500 °C for 1 h. The structural and morphological properties of the films were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The X-ray diffraction analysis shows that the films of MoO3 and WO3 were well crystallized in orthorhombic and monoclinic phase respectively with the crystallites preferentially oriented toward (2 0 0) direction parallel a-axis for both samples. In literature, we have shown in previous papers that structural and surface morphology of metal thin films play an important role in the gas detection mechanism. In this article, we have studied the response evolution of MoO3 and WO3 thin films sensors ethanol versus time, working temperature and the concentration of the ethanol. It was found that these films had high sensitivity to ethanol, which made them as a good candidate for the ethanol sensor. Finally, the photocatalytic activity of the samples was evaluated with respect to the degradation reaction of a wastewater containing methylene blue (MB) under UV-visible light irradiation. The molybdenum trioxide exhibits a higher degradation rate than the tungsten trioxide thin films under similar experimental conditions.

Influence of post-deposition annealing on structural, morphological and optical properties of copper (II) acetylacetonate thin films.

PubMed

Abdel-Khalek, H; El-Samahi, M I; El-Mahalawy, Ahmed M

2018-05-21

In this study, the effect of thermal annealing under vacuum conditions on structural, morphological and optical properties of thermally evaporated copper (II) acetylacetonate, cu(acac) 2 , thin films were investigated. The copper (II) acetylacetonate thin films were deposited using thermal evaporation technique at vacuum pressure ~1 × 10 -5  mbar. The deposited films were thermally annealed at 323, 373, 423, and 473 K for 2 h in vacuum. The thermogravimetric analysis of cu(acac) 2 powder indicated a thermal stability of cu(acac) 2 up to 423 K. The effects of thermal annealing on the structural properties of cu(acac) 2 were evaluated employing X-ray diffraction method and the analysis showed a polycrystalline nature of the as-deposited and annealed films with a preferred orientation in [1¯01] direction. Fourier transformation infrared (FTIR) technique was used to negate the decomposition of copper (II) acetylacetonate during preparation or/and annealing up to 423 K. The surface morphology of the prepared films was characterized by means of field emission scanning electron microscopy (FESEM). A significant enhancement of the morphological properties of cu(acac) 2 thin films was obtained till the annealing temperature reaches 423 K. The variation of optical constants that estimated from spectrophotometric measurements of the prepared thin films was investigated as a function of annealing temperature. The annealing process presented significantly impacted the nonlinear optical properties such as third-order optical susceptibility χ (3) and nonlinear refractive index n 2 of cu(acac) 2 thin films. Copyright © 2018 Elsevier B.V. All rights reserved.

Modeling Evaporation and Particle Assembly in Colloidal Droplets.

PubMed

Zhao, Mingfei; Yong, Xin

2017-06-13

Evaporation-induced assembly of nanoparticles in a drying droplet is of great importance in many engineering applications, including printing, coating, and thin film processing. The investigation of particle dynamics in evaporating droplets can provide fundamental hydrodynamic insight for revealing the processing-structure relationship in the particle self-organization induced by solvent evaporation. We develop a free-energy-based multiphase lattice Boltzmann method coupled with Brownian dynamics to simulate evaporating colloidal droplets on solid substrates with specified wetting properties. The influence of interface-bound nanoparticles on the surface tension and evaporation of a flat liquid-vapor interface is first quantified. The results indicate that the particles at the interface reduce surface tension and enhance evaporation flux. For evaporating particle-covered droplets on substrates with different wetting properties, we characterize the increase of evaporate rate via measuring droplet volume. We find that droplet evaporation is determined by the number density and circumferential distribution of interfacial particles. We further correlate particle dynamics and assembly to the evaporation-induced convection in the bulk and on the surface of droplet. Finally, we observe distinct final deposits from evaporating colloidal droplets with bulk-dispersed and interface-bound particles. In addition, the deposit pattern is also influenced by the equilibrium contact angle of droplet.

Effects of substrate temperatures and deposition rates on properties of aluminum fluoride thin films in deep-ultraviolet region.

PubMed

Sun, Jian; Li, Xu; Zhang, Weili; Yi, Kui; Shao, Jianda

2012-12-10

Aluminum fluoride (AlF(3)) is a low-refractive-index material widely used in coatings for deep-ultraviolet (DUV) optical systems, especially 193 nm laser systems. Low optical loss and stability are essential for film application. In this study, AlF(3)> thin films were prepared by thermal evaporation with a resistive heating boat. The effects of substrate temperatures and deposition rates on the optical properties in vacuum and in air, composition, and microstructures were discussed respectively. In vacuum the deposition parameters directly influenced the microstructures that determined the refractive index. When the films were exposed to air, aluminum oxide (Al(2)O(3)) formed in the films with water adsorption. Thus the refractive index increased and a nonmonotonic changing trend of the refractive index with substrate temperature was observed. The Al(2)O(3) was also found to be conductive to reducing absorption loss. AlF(3) films prepared at a high substrate temperature and deposition rate could yield stable structures with large optical loss.

A review-application of physical vapor deposition (PVD) and related methods in the textile industry

NASA Astrophysics Data System (ADS)

Shahidi, Sheila; Moazzenchi, Bahareh; Ghoranneviss, Mahmood

2015-09-01

Physical vapor deposition (PVD) is a coating process in which thin films are deposited by the condensation of a vaporized form of the desired film material onto the substrate. The PVD process is carried out in a vacuum. PVD processes include different types, such as: cathode arc deposition, electron beam physical vapor deposition, evaporative deposition, sputtering, ion plating and enhanced sputtering. In the PVD method, the solid coating material is evaporated by heat or by bombardment with ions (sputtering). At the same time, a reactive gas is also introduced; it forms a compound with the metal vapor and is deposited on the substrate as a thin film with highly adherent coating. Such coatings are used in a wide range of applications such as aerospace, automotive, surgical, medical, dyes and molds for all manner of material processing, cutting tools, firearms, optics, thin films and textiles. The objective of this work is to give a comprehensive description and review of the science and technology related to physical vapor deposition with particular emphasis on their potential use in the textile industry. Physical vapor deposition has opened up new possibilities in the modification of textile materials and is an exciting prospect for usage in textile design and technical textiles. The basic principle of PVD is explained and the major applications, particularly sputter coatings in the modification and functionalization of textiles, are introduced in this research.

Laboratory simulation of processes of evaporation, condensation, and sputtering taking place on the surface of the moon

NASA Technical Reports Server (NTRS)

Nusinov, M. D.; Kochnev, V. A.; Chernyak, Y. B.; Kuznetsov, A. V.; Kosolapov, A. I.; Yakovlev, O. I.

1974-01-01

Study of evaporation, condensation and sputtering on the moon can provide information on the same processes on other planets, and reveal details of the formation of the lunar regolith. Simulation methods include vacuum evaporation, laser evaporation, and bubbling gas through melts.

Raman Analysis of Dilute Aqueous Samples by Localized Evaporation of Submicroliter Droplets on the Tips of Superhydrophobic Copper Wires.

PubMed

Cheung, Melody; Lee, Wendy W Y; McCracken, John N; Larmour, Iain A; Brennan, Steven; Bell, Steven E J

2016-04-19

Raman analysis of dilute aqueous solutions is normally prevented by their low signal levels. A very general method to increase the concentration to detectable levels is to evaporate droplets of the sample to dryness, creating solid deposits which are then Raman probed. Here, superhydrophobic (SHP) wires with hydrophilic tips have been used as supports for drying droplets, which have the advantage that the residue is automatically deposited at the tip. The SHP wires were readily prepared in minutes using electroless galvanic deposition of Ag onto copper wires followed by modification with a polyfluorothiol (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decanethiol, HDFT). Cutting the coated wires with a scalpel revealed hydrophilic tips which could support droplets whose maximum size was determined by the wire diameter. Typically, 230 μm wires were used to support 0.6 μL droplets. Evaporation of dilute melamine droplets gave solid deposits which could be observed by scanning electron microscopy (SEM) and Raman spectroscopy. The limit of detection for melamine using a two stage evaporation procedure was 1 × 10(-6) mol dm(-3). The physical appearance of dried droplets of sucrose and glucose showed that the samples retained significant amounts of water, even under high vacuum. Nonetheless, the Raman detection limits of sucrose and glucose were 5 × 10(-4) and 2.5 × 10(-3) mol dm(-3), respectively, which is similar to the sensitivity reported for surface-enhanced Raman spectroscopy (SERS) detection of glucose. It was also possible to quantify the two sugars in mixtures at concentrations which were similar to those found in human blood through multivariate analysis.

Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.

PubMed

Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

2008-05-01

Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation.

Spacesuit Evaporator-Absorber-Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Hodgson, Ed; Izenson, Mike; Chan, Weibo; Bue, Grant C.

2012-01-01

For decades advanced spacesuit developers have pursued a regenerable, robust nonventing system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s Lithium Chloride Absorber Radiator (LCAR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. This water vapor is then captured by solid LiCl in the LCAR with a high enthalpy of absorption, resulting in sufficient temperature lift to reject heat to space by radiation. After the sortie, the LCAR would be heated up and dried in a regenerator to drive off and recover the absorbed evaporant. A engineering development prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The LCAR was able to stably reject 75 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

Deposition and characterization of silica-based films by helicon-activated reactive evaporation applied to optical waveguide fabrication.

PubMed

Bulla, Douglas A P; Li, Wei-Tang; Charles, Christine; Boswell, Rod; Ankiewicz, Adrian; Love, John

2004-05-10

Planar silicon dioxide optical waveguides were deposited by use of a plasma-activated reactive evaporation system, at a low deposition temperature and with reduced hydrogen contamination, on thermally oxidized silicon wafers. The deposited films show a refractive-index inhomogeneity of less than 0.1%, a thickness nonuniformity of less than 5%, and a material birefringence of approximately 5 x 10(-4). Rib-type channel waveguides were formed on the deposited films by means of hydrofluoric acid etching. The transmission loss of the rib waveguides is determined to be as low as 0.3 dB/cm at a wavelength of 1310 nm for TE polarization, after subtraction of the calculated leakage and scattering losses. Owing to the presence of the OH vibrational overtone band, an additional loss peak of 1 dB/cm is found near the 1385-nm wavelength. The experimental results of transmission loss at wavelengths of 1310 and 1550 nm are compared with analytic expressions for interface scattering and leakage loss.

Evaporation rate and vapor pressure of selected polymeric lubricating oils.

NASA Technical Reports Server (NTRS)

Gardos, M. N.

1973-01-01

A recently developed ultrahigh-vacuum quartz spring mass sorption microbalance has been utilized to measure the evaporation rates of several low-volatility polymeric lubricating oils at various temperatures. The evaporation rates are used to calculate the vapor pressures by the Langmuir equation. A method is presented to accurately estimate extended temperature range evaporation rate and vapor pressure data for polymeric oils, incorporating appropriate corrections for the increases in molecular weight and the change in volatility of the progressively evaporating polymer fractions. The logarithms of the calculated data appear to follow linear relationships within the test temperature ranges, when plotted versus 1000/T. These functions and the observed effusion characteristics of the fluids on progressive volatilization are useful in estimating evaporation rate and vapor pressure changes on evaporative depletion.

Morphology, Structural and Dielectric Properties of Vacuum Evaporated V2O5 Thin Films

NASA Astrophysics Data System (ADS)

Sengodan, R.; Shekar, B. Chandar; Sathish, S.

Vanadium pentoxide (V2O5) thin films were deposited on well cleaned glass substrate using evaporation technique under the pressure of 10-5 Torr. The thickness of the films was measured by the multiple beam interferometry technique and cross checked by using capacitance method. Metal-Insulator-Metal (MIM) structure was fabricated by using suitable masks to study dielectric properties. The dielectric properties were studied by employing LCR meter in the frequency range 12 Hz to 100 kHz for various temperatures. The temperature co- efficient of permittivity (TCP), temperature co-efficient of capacitance (TCC) and dielectric constant (ɛ) were calculated. The activation energy was calculated and found to be very low. The activation energy was found to be increasing with increase in frequency. The obtained low value of activation energy suggested that the hopping conduction may be due to electrons rather than ions.

Evaporation of Lennard-Jones fluids.

PubMed

Cheng, Shengfeng; Lechman, Jeremy B; Plimpton, Steven J; Grest, Gary S

2011-06-14

Evaporation and condensation at a liquid/vapor interface are ubiquitous interphase mass and energy transfer phenomena that are still not well understood. We have carried out large scale molecular dynamics simulations of Lennard-Jones (LJ) fluids composed of monomers, dimers, or trimers to investigate these processes with molecular detail. For LJ monomers in contact with a vacuum, the evaporation rate is found to be very high with significant evaporative cooling and an accompanying density gradient in the liquid domain near the liquid/vapor interface. Increasing the chain length to just dimers significantly reduces the evaporation rate. We confirm that mechanical equilibrium plays a key role in determining the evaporation rate and the density and temperature profiles across the liquid/vapor interface. The velocity distributions of evaporated molecules and the evaporation and condensation coefficients are measured and compared to the predictions of an existing model based on kinetic theory of gases. Our results indicate that for both monatomic and polyatomic molecules, the evaporation and condensation coefficients are equal when systems are not far from equilibrium and smaller than one, and decrease with increasing temperature. For the same reduced temperature T/T(c), where T(c) is the critical temperature, these two coefficients are higher for LJ dimers and trimers than for monomers, in contrast to the traditional viewpoint that they are close to unity for monatomic molecules and decrease for polyatomic molecules. Furthermore, data for the two coefficients collapse onto a master curve when plotted against a translational length ratio between the liquid and vapor phase.

Advanced performance of small diaphragm vacuum pumps through the use of mechatronics

NASA Astrophysics Data System (ADS)

Lachenmann, R.; Dirscherl, J.

Oil-free diaphragm vacuum pumps have proven to be the best way in vacuum generation for the chemical laboratory and they also find increasing use as backing pumps for modern wide-range turbo molecular pumps. The majority of vacuum pumps in practical use pump only a rather small percentage of their lifetime at full gas load. A pump backing a turbo molecular pump does not have to pump a significant gas load when the high-vacuum pump is running at ultimate vacuum pressure. Also, for a vacuum distillation the vacuum pump has to operate at full speed only at the beginning to lower the pressure inside the system to a vacuum level where evaporation starts. In a rather leak-tight system the distillation process continues by evaporating from the hot liquid and condensing at the cold condenser without the need of a mechanical vacuum pump. Rotational speed controlled diaphragm pumps are now available through progress in mechatronics and offer high pumping speed capability for fast pump-down cycles and precise pressure control for distillations. At low gas load the rotational speed can be reduced, improving maintenance intervals, power consumption, noise, vibration and - surprisingly - also ultimate pressure. The different behaviour in pumping speed and ultimate pressure of rotational speed controlled diaphragm pumps in comparison to constant-speed pumps is related to the mechanical properties of the valves and gas dynamics .

Organic semiconductor rubrene thin films deposited by pulsed laser evaporation of solidified solutions

NASA Astrophysics Data System (ADS)

Majewska, N.; Gazda, M.; Jendrzejewski, R.; Majumdar, S.; Sawczak, M.; Śliwiński, G.

2017-08-01

Organic semiconductor rubrene (C42H28) belongs to most preferred spintronic materials because of the high charge carrier mobility up to 40 cm2(V·s)-1. However, the fabrication of a defect-free, polycrystalline rubrene for spintronic applications represents a difficult task. We report preparation and properties of rubrene thin films deposited by pulsed laser evaporation of solidified solutions. Samples of rubrene dissolved in aromatic solvents toluene, xylene, dichloromethane and 1,1-dichloroethane (0.23-1% wt) were cooled to temperatures in the range of 16.5-163 K and served as targets. The target ablation was provided by a pulsed 1064 nm or 266 nm laser. For films of thickness up to 100 nm deposited on Si, glass and ITO glass substrates, the Raman and AFM data show presence of the mixed crystalline and amorphous rubrene phases. Agglomerates of rubrene crystals are revealed by SEM observation too, and presence of oxide/peroxide (C42H28O2) in the films is concluded from matrix-assisted laser desorption/ionization time-of-flight spectroscopic analysis.

Lithium Nitride Synthesized by in situ Lithium Deposition and Ion Implantation for Boron Neutron Capture Therapy

NASA Astrophysics Data System (ADS)

Ishitama, Shintaro; Baba, Yuji; Fujii, Ryo; Nakamura, Masaru; Imahori, Yoshio

Li3N synthesis on Li deposition layer was conducted without H2O and O2 by in situ lithium deposition in high vacuum chamber of 10-6 Pa and ion implantation techniques and the thermo-chemical stability of the Li3N/Li/Cu tri-layered target for Boron Neutron Capture Therapy (BNCT) under laser heating and air exposure was characterized by X-ray photoelectron spectroscopy (XPS). Following conclusions were derived; (1) Li3N/Li/Cu tri-layered target with very low oxide and carbon contamination was synthesized by in situ lithium vacuum deposition and N2+ ion implantation without H2O and O2 additions, (2) The starting temperature of evaporation of Li3N/Li/Cu tri-layered target increased by 120K compared to that of the Li/Cu target and (3) Remarkable oxidation and carbon contamination were observed on the surface of Li3N/Li/Cu after air exposure and these contaminated compositions was not removed by Ar+ heavy sputtering.

Formation of β-FeSi 2 thin films by partially ionized vapor deposition

NASA Astrophysics Data System (ADS)

Harada, Noriyuki; Takai, Hiroshi

2003-05-01

The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

Spacesuit Evaporator-Absorber-Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Hodgson, Ed; Izenso, Mike; Chan, Weibo; Cupples, Scott

2011-01-01

For decades advanced spacesuit developers have pursued a regenerable, robust non-venting system for heat rejection. Toward this end, this paper investigates linking together two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's lithium chloride Heat Pump Radiator (HPR). Heat from a liquid cooled garment is transported to SWME that provides cooling through evaporation. The SEAR is evacuated at the onset of operations and thereafter, the water vapor absorption rate of the HPR maintains a low pressure environment for the SWME to evaporate effectively. This water vapor captured by solid LiCl in the HPR with a high enthalpy of absorption, results in sufficient temperature lift to reject most of the heat to space by radiation. After the sortie, the HPR would be heated up in a regenerator to drive off and recover the absorbed evaporant. A one-fourth scale prototype was built and tested in vacuum conditions at a sink temperature of 250 K. The HPR was able to stably reject 60 W over a 7-hour period. A conceptual design of a full-scale radiator is proposed. Excess heat rejection above 240 W would be accomplished through venting of the evaporant. Loop closure rates were predicted for various exploration environment scenarios.

Optimizing the vacuum plasma spray deposition of metal, ceramic, and cermet coatings using designed experiments

NASA Astrophysics Data System (ADS)

Kingswell, R.; Scott, K. T.; Wassell, L. L.

1993-06-01

The vacuum plasma spray (VPS) deposition of metal, ceramic, and cermet coatings has been investigated using designed statistical experiments. Processing conditions that were considered likely to have a significant influence on the melting characteristics of the precursor powders and hence deposition efficiency were incorporated into full and fractional factorial experimental designs. The processing of an alumina powder was very sensitive to variations in the deposition conditions, particularly the injection velocity of the powder into the plasma flame, the plasma gas composition, and the power supplied to the gun. Using a combination of full and fractional factorial experimental designs, it was possible to rapidly identify the important spraying variables and adjust these to produce a deposition efficiency approaching 80 percent. The deposition of a nickel-base alloy metal powder was less sensitive to processing conditions. Generally, however, a high degree of particle melting was achieved for a wide range of spray conditions. Preliminary experiments performed using a tungsten carbide/cobalt cermet powder indicated that spray efficiency was not sensitive to deposition conditions. However, microstructural analysis revealed considerable variations in the degree of tungsten carbide dissolution. The structure and properties of the optimized coatings produced in the factorial experiments are also discussed.

Study of optical properties of vacuum evaporated carbon nanotube containing Se80Te16Cu4 thin films

NASA Astrophysics Data System (ADS)

Upadhyay, A. N.; Tiwari, R. S.; Singh, Kedar

2016-08-01

Thin films of Se80Te16Cu4 glassy alloy and 3 wt.% of carbon nanotubes (CNTs) containing Se80Te16Cu4 glassy composite were deposited on clean glass substrate by thermal evaporation technique. The scanning electron microscope and energy dispersive x-ray analysis were performed to investigate the surface morphology and elemental composition of as synthesised samples. The reflectance and transmittance spectra of as-deposited thin films were recorded (200-1100 nm) by using UV/VIS/NIR spectrophotometer. The optical band gap and optical constants such as absorption coefficient (α), refractive index (n) and extinction coefficient (k) of Se80Te16Cu4 and 3 wt.% CNTs-Se80Te16Cu4 glassy composite thin films were calculated. It is observed that optical properties alter due to CNTs incorporation in Se80Te16Cu4 glassy alloy. Effect on optical properties due to CNTs incorporation can be explained in terms of concentration of unsaturated bonds/defects in the localised states.

Formation of coffee-stain patterns at the nanoscale: The role of nanoparticle solubility and solvent evaporation rate.

PubMed

Zhang, Jianguo; Milzetti, Jasmin; Leroy, Frédéric; Müller-Plathe, Florian

2017-03-21

When droplets of nanoparticle suspension evaporate from surfaces, they leave behind a deposit of nanoparticles. The mechanism of evaporation-induced pattern formation in the deposit is studied by molecular dynamics simulations for sessile nanodroplets. The influence of the interaction between nanoparticles and liquid molecules and the influence of the evaporation rate on the final deposition pattern are addressed. When the nanoparticle-liquid interaction is weaker than the liquid-liquid interaction, an interaction-driven or evaporation-induced layer of nanoparticles appears at the liquid-vapor interface and eventually collapses onto the solid surface to form a uniform deposit independently of the evaporation rate. When the nanoparticle-liquid and liquid-liquid interactions are comparable, the nanoparticles are dispersed inside the droplet and evaporation takes place with the contact line pinned at a surface defect. In such a case, a pattern with an approximate ring-like shape is found with fast evaporation, while a more uniform distribution is observed with slower evaporation. When the liquid-nanoparticle interaction is stronger than the liquid-liquid interaction, evaporation always occurs with receding contact line. The final deposition pattern changes from volcano-like to pancake-like with decreasing evaporation rate. These findings might help to design nanoscale structures like nanopatterns or nanowires on surface through controlled solvent evaporation.

Formation of coffee-stain patterns at the nanoscale: The role of nanoparticle solubility and solvent evaporation rate

NASA Astrophysics Data System (ADS)

Zhang, Jianguo; Milzetti, Jasmin; Leroy, Frédéric; Müller-Plathe, Florian

2017-03-01

When droplets of nanoparticle suspension evaporate from surfaces, they leave behind a deposit of nanoparticles. The mechanism of evaporation-induced pattern formation in the deposit is studied by molecular dynamics simulations for sessile nanodroplets. The influence of the interaction between nanoparticles and liquid molecules and the influence of the evaporation rate on the final deposition pattern are addressed. When the nanoparticle-liquid interaction is weaker than the liquid-liquid interaction, an interaction-driven or evaporation-induced layer of nanoparticles appears at the liquid-vapor interface and eventually collapses onto the solid surface to form a uniform deposit independently of the evaporation rate. When the nanoparticle-liquid and liquid-liquid interactions are comparable, the nanoparticles are dispersed inside the droplet and evaporation takes place with the contact line pinned at a surface defect. In such a case, a pattern with an approximate ring-like shape is found with fast evaporation, while a more uniform distribution is observed with slower evaporation. When the liquid-nanoparticle interaction is stronger than the liquid-liquid interaction, evaporation always occurs with receding contact line. The final deposition pattern changes from volcano-like to pancake-like with decreasing evaporation rate. These findings might help to design nanoscale structures like nanopatterns or nanowires on surface through controlled solvent evaporation.

Evaporation of pure liquid sessile and spherical suspended drops: a review.

PubMed

Erbil, H Yildirim

2012-01-15

A sessile drop is an isolated drop which has been deposited on a solid substrate where the wetted area is limited by a contact line and characterized by contact angle, contact radius and drop height. Diffusion-controlled evaporation of a sessile drop in an ambient gas is an important topic of interest because it plays a crucial role in many scientific applications such as controlling the deposition of particles on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, drop wise cooling, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials in the last decades. This paper presents a review of the published articles for a period of approximately 120 years related to the evaporation of both sessile drops and nearly spherical droplets suspended from thin fibers. After presenting a brief history of the subject, we discuss the basic theory comprising evaporation of micrometer and millimeter sized spherical drops, self cooling on the drop surface and evaporation rate of sessile drops on solids. The effects of drop cooling, resultant lateral evaporative flux and Marangoni flows on evaporation rate are also discussed. This review also has some special topics such as drop evaporation on superhydrophobic surfaces, determination of the receding contact angle from drop evaporation, substrate thermal conductivity effect on drop evaporation and the rate evaporation of water in liquid marbles. Copyright © 2011 Elsevier B.V. All rights reserved.

Electron Emission Observations from As-Grown and Vacuum-Coated Chemical Vapor Deposited Diamond

NASA Technical Reports Server (NTRS)

Lamouri, A.; Wang, Yaxin; Mearini, G. T.; Krainsky, I. L.; Dayton, J. A., Jr.; Mueller,W.

1996-01-01

Field emission has been observed from chemical vapor deposited diamond grown on Mo and Si substrates. Emission was observed at fields as low as 20 kV/cm. The samples were tested in the as-grown form, and after coating with thin films of Au, CsI, and Ni. The emission current was typically maximum at the onset of the applied field, but was unstable, and decreased rapidly with time from the as-grown films. Thin Au layers, approximately 15 nm thick, vacuum deposited onto the diamond samples significantly improved the stability of the emission current at values approximately equal to those from uncoated samples at the onset of the applied field. Thin layers of CsI, approximately 5 nm thick, were also observed to improve the stability of the emission current but at values less than those from the uncoated samples at the onset of the applied field. While Au and CsI improved the stability of the emission, Ni was observed to have no effect.

ZnO synthesis by high vacuum plasma-assisted chemical vapor deposition using dimethylzinc and atomic oxygen

NASA Astrophysics Data System (ADS)

Barnes, Teresa M.; Hand, Steve; Leaf, Jackie; Wolden, Colin A.

2004-09-01

Zinc oxide thin films were produced by high vacuum plasma-assisted chemical vapor deposition (HVP-CVD) from dimethylzinc (DMZn) and atomic oxygen. HVP-CVD is differentiated from conventional remote plasma-enhanced CVD in that the operating pressures of the inductively coupled plasma (ICP) source and the deposition chamber are decoupled. Both DMZn and atomic oxygen effuse into the deposition chamber under near collisionless conditions. The deposition rate was measured as a function of DMZn and atomic oxygen flux on glass and silicon substrates. Optical emission spectroscopy and quadrupole mass spectrometry (QMS) were used to provide real time analysis of the ICP source and the deposition chamber. The deposition rate was found to be first order in DMZn pressure and zero order in atomic oxygen density. All films demonstrated excellent transparency and were preferentially orientated along the c-axis. The deposition chemistry occurs exclusively through surface-mediated reactions, since the collisionless transport environment eliminates gas-phase chemistry. QMS analysis revealed that DMZn was almost completely consumed, and desorption of unreacted methyl radicals was greatly accelerated in the presence of atomic oxygen. Negligible zinc was detected in the gas phase, suggesting that Zn was efficiently consumed on the substrate and walls of the reactor.

Synthesis of lithium nitride for neutron production target of BNCT by in situ lithium deposition and ion implantation

NASA Astrophysics Data System (ADS)

Ishiyama, S.; Baba, Y.; Fujii, R.; Nakamura, M.; Imahori, Y.

2012-12-01

To achieve high performance of BNCT (Boron Neutron Capture Therapy) device, Li3N/Li/Pd/Cu four layered Li target was designed and the structures of the synthesized four layered target were characterized by X-ray photoelectron spectroscopy. For the purpose of avoiding the radiation blistering and lithium evaporation, in situ vacuum deposition and nitridation techniques were established for in situ production and repairing maintenance of the lithium target. Following conclusions were derived: Uniform lithium layer of a few hundreds nanometer was formed on Pd/Cu multilayer surface by in situ vacuum deposition technique using metallic lithium as a source material. Lithium nitrides were formed by in situ nitridation reaction by the implantation of low-energy nitrogen ions on the deposited lithium layer surface. The chemical states of the nitridated zone were close to the stoichiometric lithium nitride, Li3N. This nitridated zone formed on surface of four layered lithium target is stable for a long time in air condition. The in situ nitridation is effective to protect lithium target from degradation by unfavorable reactions.

Numerical modeling of carrier gas flow in atomic layer deposition vacuum reactor: A comparative study of lattice Boltzmann models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pan, Dongqing; Chien Jen, Tien; Li, Tao

2014-01-15

This paper characterizes the carrier gas flow in the atomic layer deposition (ALD) vacuum reactor by introducing Lattice Boltzmann Method (LBM) to the ALD simulation through a comparative study of two LBM models. Numerical models of gas flow are constructed and implemented in two-dimensional geometry based on lattice Bhatnagar–Gross–Krook (LBGK)-D2Q9 model and two-relaxation-time (TRT) model. Both incompressible and compressible scenarios are simulated and the two models are compared in the aspects of flow features, stability, and efficiency. Our simulation outcome reveals that, for our specific ALD vacuum reactor, TRT model generates better steady laminar flow features all over the domainmore » with better stability and reliability than LBGK-D2Q9 model especially when considering the compressible effects of the gas flow. The LBM-TRT is verified indirectly by comparing the numerical result with conventional continuum-based computational fluid dynamics solvers, and it shows very good agreement with these conventional methods. The velocity field of carrier gas flow through ALD vacuum reactor was characterized by LBM-TRT model finally. The flow in ALD is in a laminar steady state with velocity concentrated at the corners and around the wafer. The effects of flow fields on precursor distributions, surface absorptions, and surface reactions are discussed in detail. Steady and evenly distributed velocity field contribute to higher precursor concentration near the wafer and relatively lower particle velocities help to achieve better surface adsorption and deposition. The ALD reactor geometry needs to be considered carefully if a steady and laminar flow field around the wafer and better surface deposition are desired.« less

New insights into saline water evaporation from porous media: Complex interaction between evaporation rates, precipitation, and surface temperature

NASA Astrophysics Data System (ADS)

Shokri-Kuehni, Salomé M. S.; Vetter, Thomas; Webb, Colin; Shokri, Nima

2017-06-01

Understanding salt transport and deposition patterns during evaporation from porous media is important in many engineering and hydrological processes such as soil salinization, ecosystem functioning, and land-atmosphere interaction. As evaporation proceeds, salt concentration increases until it exceeds solubility limits, locally, and crystals precipitate. The interplay between transport processes, crystallization, and evaporation influences where crystallization occurs. During early stages, the precipitated salt creates an evolving porous structure affecting the evaporation kinetics. We conducted a comprehensive series of experiments to investigate how the salt concentration and precipitation influence evaporation dynamics. Our results illustrate the contribution of the evolving salt crust to the evaporative mass losses. High-resolution thermal imaging enabled us to investigate the complex temperature dynamics at the surface of precipitated salt, providing further confirmation of salt crust contribution to the evaporation. We identify different phases of saline water evaporation from porous media with the corresponding dominant mechanisms in each phase and extend the physical understanding of such processes.

Evaporation behavior of lithium, potassium, uranium and rare earth chlorides in pyroprocessing

NASA Astrophysics Data System (ADS)

Jang, Junhyuk; Kim, Tackjin; Park, Sungbin; Kim, Gha-Young; Kim, Sihyoung; Lee, Sungjai

2017-12-01

The evaporation behaviors of Li, K, U, and rare earth (RE) chlorides were examined for the cathode process in pyroprocessing. The evaporation temperatures of the chlorides were evaluated in vacuum by measuring the weight decrease. In addition, an evaporation test up to 1473 K of the cathode process using a surrogate mixture of uranium and chlorides was conducted. It was found that LiCl evaporated more readily than the other chlorides. The weight of LiCl was rapidly decreased at temperatures above 981 K, while that of KCl was decreased above 1035 K, indicating the evaporation. UCl3 evaporated at temperatures above 1103 K. RE chlorides showed a similar evaporation behavior, evaporating first at 1158 K then rapidly evaporating at temperatures above 1230 K. Thus, the order of evaporation with increasing temperature was found to be LiCl < KCl < UCl3 < RE chlorides, with different RE chlorides evaporating at similar temperature. The surrogate test confirmed the observed evaporation trend of the chlorides during the cathode process, and revealed that the contamination of uranium remains by the back-reaction of RE chlorides is negligible.

Solid-state acquisition of fingermark topology using dense columnar thin films.

PubMed

Lakhtakia, Akhlesh; Shaler, Robert C; Martín-Palma, Raúl J; Motyka, Michael A; Pulsifer, Drew P

2011-05-01

Various vacuum techniques are employed to develop fingermarks on evidentiary items. In this work, a vacuum was used to deposit columnar thin films (CTFs) on untreated, cyanoacrylate-fumed or dusted fingermarks on a limited selection of nonporous surfaces (microscope glass slides and evidence tape). CTF deposition was not attempted on fingermarks deposited on porous surfaces. The fingermarks were placed in a vacuum chamber with the fingermark side facing an evaporating source boat containing either chalcogenide glass or MgF(2). Thermal evaporation of chalcogenide glass or MgF(2) under a 1 μTorr vacuum for 30 min formed dense CTFs on fingermark ridges, capturing the topographical features. The results show that it is possible to capture fingermark topology using CTFs on selected untreated, vacuumed cyanoacrylate-fumed or black powder-dusted nonporous surfaces. Additionally, the results suggested this might be a mechanism to help elucidate the sequence of deposition. © 2011 American Academy of Forensic Sciences.

Isotope mass fractionation during evaporation of Mg2SiO4

NASA Technical Reports Server (NTRS)

Davis, Andrew M.; Clayton, Robert N.; Mayeda, Toshiko K.; Hashimoto, Akihiko

1990-01-01

Synthetic forsterite (Mg2SiO4) was partially evaporated in vacuum for various durations and at different temperatures. The residual charges obtained when molten Mg2SiO4 was evaporated to 12 percent of its initial mass were enriched in heavy isotopes by about 20, 30, and 15 per mil/amu for O, Mg, and Si, respectively, whereas solid forsterite evaporated to a similar residual mass fraction showed negligible fractionations. These results imply that calcium and aluminum-rich refractory inclusions in carbonaceous chondrites must have been at least partially molten in the primordial solar nebula if the observed large mass fractionation effects were caused by evaporation processes in the nebula.

Atmospheric dry deposition in the vicinity of the Salton Sea, California - II: Measurement and effects of an enhanced evaporation system

USGS Publications Warehouse

Alonso, R.; Bytnerowicz, A.; Yee, J.L.; Boarman, W.I.

2005-01-01

A study was conducted to determine the effects of salt spray drift from pilot technologies employed by the US Bureau of Reclamation on deposition rates of various air-born ions. An enhanced evaporation system (EES) was tested in the field at the Salton Sea, California. Dry deposition of NO3-, NH4+, SO42-, Cl-, Ca2+, Na+, K+ and Se was assessed by using nylon filters and branches of natural vegetation exposed for one-week long periods. The simultaneous exposure of both lyophilized branches and branches of live plants offered important information highlighting the dynamics of deposited ions on vegetation. The EES significantly increased the deposition rates of Cl-, SO42- and Na+ in an area of about 639-1062 m surrounding the sprayers. Similarly, higher deposition of Ca 2+ and K+ caused by the EES was detected only when deposition was assessed using nylon filters or lyophilized branches. Deposition fluxes of NO3-, NH4+ and Se were not affected by the spraying system. Techniques for measuring dry deposition and calculating landscape-level depositional loads in non-forested systems need further development. ?? 2005 Elsevier Ltd. All rights reserved.

Multi-chamber deposition system

DOEpatents

Jacobson, Richard L.; Jeffrey, Frank R.; Westerberg, Roger K.

1989-10-17

A system for the simultaneous deposition of different coatings onto a thin web within a large volume vacuum chamber is disclosed which chamber is provided with a plurality of deposition chambers in which the different layers are deposited onto the film as its moves from a supply roll to a finished take-up roll of coated web. The deposition chambers provided within the large vacuum chamber are provided with separate seals which minimize back diffusion of any dopant gas from adjacent deposition chambers.

Multi-chamber deposition system

DOEpatents

Jacobson, Richard L.; Jeffrey, Frank R.; Westerberg, Roger K.

1989-06-27

A system for the simultaneous deposition of different coatings onto a thin web within a large volume vacuum chamber is disclosed which chamber is provided with a plurality of deposition chambers in which the different layers are deposited onto the film as its moves from a supply roll to a finished take-up roll of coated web. The deposition chambers provided within the large vacuum chamber are provided with separate seals which minimize back diffusion of any dopant gas from adjacent deposition chambers.

Evaporation-induced patterns from droplets containing motile and nonmotile bacteria.

PubMed

Nellimoottil, Tittu Thomas; Rao, Pinjala Nagaraju; Ghosh, Siddhartha Sankar; Chattopadhyay, Arun

2007-08-14

In this letter, we report the observations of specific pattern formation from the evaporation of aqueous droplets containing motile and nonmotile bacteria. We found that when motile bacteria were present the droplet evaporated into disclike patterned deposits of bacteria. However, when the bacteria were made nonmotile by treatment with liquid nitrogen, the droplet evaporated into ringlike deposits. We also observed that bacteria with higher motility produced more uniformly deposited disclike patterns. Furthermore, we propose a model with numerical simulations to explain the mechanism of formation of these patterns. The model is based on the advective fluid flow from the center of the droplet toward the edge due to enhanced evaporation from the edge of the pinned droplet in comparison to that from the free surface. For the case of motile bacteria, we have added another velocity parameter toward the axis of the droplet and directed against the fluid flow in order to account for the disclike pattern formation. The numerical simulations match the experimental observations well. The present work, by qualitative and quantitative understanding of the evaporation of bacteria droplets, demonstrates that the inherent bacterial motility is primarily responsible for the formation of these differential patterns.

Effects of substrate heating and vacuum annealing on optical and electrical properties of alumina-doped ZnO films deposited by DC magnetron sputtering

NASA Astrophysics Data System (ADS)

Tang, Chien-Jen; Wang, Chun-Yuan; Jaing, Cheng-Chung

2011-10-01

Alumina-doped zinc oxide (AZO) films have wide range of applications in optical and optoelectronic devices. AZO films have advantage in high transparency, high stability to hydrogen plasma and low cost to alternative ITO film. AZO film was prepared by direct-current (DC) magnetron sputtering from ceramic ZnO:Al2O3 target. The AZO films were compared in two different conditions. The first is substrate heating process, in which AZO film was deposited by different substrate temperature, room temperature, 150 °C and 250 °C. The second is vacuum annealing process, in which AZO film with deposited at room temperature have been annealed at 250 °C and 450 °C in vacuum. The optical properties, electrical properties, grain size and surface structure properties of the films were studied by UV-VIS-NIR spectrophotometer, Hall effect measurement equipment, x-ray diffraction, and scanning electron microscopy. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 1.92×10-3 Ω-cm, 6.38 cm2/Vs, 5.08×1020 #/cm3, and 31.48 nm respectively, in vacuum annealing of 450 °C. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 8.72×10-4 Ω-cm, 6.32 cm2/Vs, 1.13×1021 #/cm3, and 31.56 nm, respectively, when substrate temperature was at 250 °C. Substrate heating process is better than vacuum annealed process for AZO film deposited by DC Magnetron Sputtering.

Hollow-Fiber Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

2013-01-01

The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

Photoinduced charge transfer from vacuum-deposited molecules to single-layer transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Osada, Kazuki; Tanaka, Masatoshi; Ohno, Shinya; Suzuki, Takanori

2016-06-01

Variations of photoluminescence (PL) and Raman spectra of single-layer MoS2, MoSe2, WS2, and WSe2 due to the vacuum deposition of C60 or copper phthalocyanine (CuPc) molecules have been investigated. PL spectra are decomposed into two competitive components, an exciton and a charged exciton (trion), depending on carrier density. The variation of PL spectra is interpreted in terms of charge transfer across the interfaces between transition metal dichalcogenides (TMDs) and dopant molecules. We find that deposited C60 molecules inject photoexcited electrons into MoS2, MoSe2, and WS2 or holes into WSe2. CuPc molecules also inject electrons into MoS2, MoSe2, and WS2, while holes are depleted from WSe2 to CuPc. We then propose a band alignment between TMDs and dopant molecules. Peak shifts of Raman spectra and doped carrier density estimated using a three-level model also support the band alignment. We thus demonstrate photoinduced charge transfer from dopant molecules to single-layer TMDs.

Microbial analysis of meatballs cooled with vacuum and conventional cooling.

PubMed

Ozturk, Hande Mutlu; Ozturk, Harun Kemal; Koçar, Gunnur

2017-08-01

Vacuum cooling is a rapid evaporative cooling technique and can be used for pre-cooling of leafy vegetables, mushroom, bakery, fishery, sauces, cooked food, meat and particulate foods. The aim of this study was to apply the vacuum cooling and the conventional cooling techniques for the cooling of the meatball and to show the vacuum pressure effect on the cooling time, the temperature decrease and microbial growth rate. The results of the vacuum cooling and the conventional cooling (cooling in the refrigerator) were compared with each other for different temperatures. The study shows that the conventional cooling was much slower than the vacuum cooling. Moreover, the microbial growth rate of the vacuum cooling was extremely low compared with the conventional cooling. Thus, the lowest microbial growth occurred at 0.7 kPa and the highest microbial growth was observed at 1.5 kPa for the vacuum cooling. The mass loss ratio for the conventional cooling and vacuum cooling was about 5 and 9% respectively.

Cu(In,Ga)Se2 solar cells with In2S3 buffer layer deposited by thermal evaporation

NASA Astrophysics Data System (ADS)

Kim, SeongYeon; Rana, Tanka R.; Kim, JunHo; Yun, JaeHo

2017-12-01

We report on physical vapor deposition of indium sulfide (In2S3) buffer layers and its application to Cu(In,Ga)Se2 (CIGSe) thin film solar cell. The Indium sulfide buffer layers were evaporated onto CIGSe at various substrate temperatures from room temperature (RT) to 350 °C. The effect of deposition temperature of buffer layers on the solar cell device performance were investigated by analyzing temperature dependent current-voltage ( J- V- T), external quantum efficiency (EQE) and Raman spectroscopy. The fabricated device showed the highest power conversion efficiency of 6.56% at substrate temperature of 250 °C, which is due to the decreased interface recombination. However, the roll-over in J- V curves was observed for solar cell device having buffer deposited at substrate temperature larger than 250 °C. From the measurement results, the interface defect and roll-over related degradation were found to have limitation on the performance of solar cell device.

Titanium dioxide antireflection coating for silicon solar cells by spray deposition

NASA Technical Reports Server (NTRS)

Kern, W.; Tracy, E.

1980-01-01

A high-speed production process is described for depositing a single-layer, quarter-wavelength thick antireflection coating of titanium dioxide on metal-patterned single-crystal silicon solar cells for terrestrial applications. Controlled atomization spraying of an organotitanium solution was selected as the most cost-effective method of film deposition using commercial automated equipment. The optimal composition consists of titanium isopropoxide as the titanium source, n-butyl acetate as the diluent solvent, sec-butanol as the leveling agent, and 2-ethyl-1-hexanol to render the material uniformly depositable. Application of the process to the coating of circular, large-diameter solar cells with either screen-printed silver metallization or with vacuum-evaporated Ti/Pd/Ag metallization showed increases of over 40% in the electrical conversion efficiency. Optical characteristics, corrosion resistance, and several other important properties of the spray-deposited film are reported. Experimental evidence indicates a wide tolerance in the coating thickness upon the overall efficiency of the cell. Considerations pertaining to the optimization of AR coatings in general are discussed, and a comprehensive critical survey of the literature is presented.

High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiency

NASA Astrophysics Data System (ADS)

Che, Xiaozhou; Li, Yongxi; Qu, Yue; Forrest, Stephen R.

2018-05-01

Multijunction solar cells are effective for increasing the power conversion efficiency beyond that of single-junction cells. Indeed, the highest solar cell efficiencies have been achieved using two or more subcells to adequately cover the solar spectrum. However, the efficiencies of organic multijunction solar cells are ultimately limited by the lack of high-performance, near-infrared absorbing organic subcells within the stack. Here, we demonstrate a tandem cell with an efficiency of 15.0 ± 0.3% (for 2 mm2 cells) that combines a solution-processed non-fullerene-acceptor-based infrared absorbing subcell on a visible-absorbing fullerene-based subcell grown by vacuum thermal evaporation. The hydrophilic-hydrophobic interface within the charge-recombination zone that connects the two subcells leads to >95% fabrication yield among more than 130 devices, and with areas up to 1 cm2. The ability to stack solution-based on vapour-deposited cells provides significant flexibility in design over the current, all-vapour-deposited multijunction structures.

Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.; Almlie, Jay C.

2010-01-01

A water membrane evaporator (WME) has been conceived and tested as an alternative to the contamination-sensitive and corrosion-prone evaporators currently used for dissipating heat from space vehicles. The WME consists mainly of the following components: An outer stainless-steel screen that provides structural support for the components mentioned next; Inside and in contact with the stainless-steel screen, a hydrophobic membrane that is permeable to water vapor; Inside and in contact with the hydrophobic membrane, a hydrophilic membrane that transports the liquid feedwater to the inner surface of the hydrophobic membrane; Inside and in contact with the hydrophilic membrane, an annular array of tubes through which flows the spacecraft coolant carrying the heat to be dissipated; and An inner exclusion tube that limits the volume of feedwater in the WME. In operation, a pressurized feedwater reservoir is connected to the volume between the exclusion tube and the coolant tubes. Feedwater fills the volume, saturates the hydrophilic membrane, and is retained by the hydrophobic membrane. The outside of the WME is exposed to space vacuum. Heat from the spacecraft coolant is conducted through the tube walls and the water-saturated hydrophilic membrane to the liquid/vapor interface at the hydrophobic membrane, causing water to evaporate to space. Makeup water flows into the hydrophilic membrane through gaps between the coolant tubes.

Cu2ZnGeS4 thin films deposited by thermal evaporation: the impact of Ge concentration on physical properties

NASA Astrophysics Data System (ADS)

Courel, Maykel; Sanchez, T. G.; Mathews, N. R.; Mathew, X.

2018-03-01

In this work, the processing of Cu2ZnGeS4 (CZGS) thin films by a thermal evaporation technique starting from CuS, GeS and ZnS precursors, and post-deposition thermal processing, is discussed. Batches of films with GeS layers of varying thicknesses are deposited in order to study the role of Ge concentration on the structural, morphological, optical and electrical properties of CZGS films. The formation of the CZGS compound with a tetragonal phase and a kesterite structure is confirmed for all samples using XRD and Raman studies. An improvement in crystallite size for Ge-poor films is also observed in the XRD analysis, which is in good agreement with the grain size observed in the cross section SEM image. Furthermore, it is found that the band-gap of CZGS film can be tailored in the range of 2.0-2.23 eV by varying Ge concentration. A comprehensive electrical characterization is also performed which demonstrates that slightly Ge-poor samples are described by the lowest grain boundary defect densities and the highest photosensitivity and mobility values. A study of the work function of CZGS samples with different Ge concentrations is also presented. Finally, a theoretical evaluation is presented, considering, under ideal conditions, the possible impact of these films on device performance. Based on the characterization results, it is concluded that Ge-poor CZGS samples deposited by thermal evaporation present better physical properties for device applications.

Optical band gap of thermally deposited Ge-S-Ga thin films

NASA Astrophysics Data System (ADS)

Rana, Anjli; Heera, Pawan; Singh, Bhanu Pratap; Sharma, Raman

2018-05-01

Thin films of Ge20S80-xGax glassy alloy, obtained from melt quenching technique, were deposited on the glass substrate by thermal evaporation technique under a high vacuum conditions (˜ 10-5 Torr). Absorption spectrum fitting method (ASF) is employed to obtain the optical band gap from absorption spectra. This method requires only the measurement of the absorption spectrum of the sample. The width of the band tail was also determined. Optical band gap computed from absorption spectra is found to decrease with an increase in Ga content. The evaluated optical band gap (Eg) is in well agreement with the theoretically predicted Eg and obtained from transmission spectra.

MEANS AND METHOD FOR PRODUCING A VACUUM

DOEpatents

Otavka, M.A.

1960-08-01

A new method is given for starting the operation of evapor-ion vacuum pumps. Ordinarily this type of pump is started by inducing an electric field with the vacuum chamber; however, by placing such an electric field in the chamber at the outset, a glow discharge may be initiated which is harmful to the pump. The procedure consists of using a negative electric field during which time only gettering action takes place; subsequently when the field reverses after a sufficient reduction of the number of gaseous particles in the chamber both gettering and ionizing takes place.

Diffraction-limited storage-ring vacuum technology

PubMed Central

Al-Dmour, Eshraq; Ahlback, Jonny; Einfeld, Dieter; Tavares, Pedro Fernandes; Grabski, Marek

2014-01-01

Some of the characteristics of recent ultralow-emittance storage-ring designs and possibly future diffraction-limited storage rings are a compact lattice combined with small magnet apertures. Such requirements present a challenge for the design and performance of the vacuum system. The vacuum system should provide the required vacuum pressure for machine operation and be able to handle the heat load from synchrotron radiation. Small magnet apertures result in the conductance of the chamber being low, and lumped pumps are ineffective. One way to provide the required vacuum level is by distributed pumping, which can be realised by the use of a non-evaporable getter (NEG) coating of the chamber walls. It may not be possible to use crotch absorbers to absorb the heat from the synchrotron radiation because an antechamber is difficult to realise with such a compact lattice. To solve this, the chamber walls can work as distributed absorbers if they are made of a material with good thermal conductivity, and distributed cooling is used at the location where the synchrotron radiation hits the wall. The vacuum system of the 3 GeV storage ring of MAX IV is used as an example of possible solutions for vacuum technologies for diffraction-limited storage rings. PMID:25177979

Transparent conducting ZnO-CdO thin films deposited by e-beam evaporation technique

NASA Astrophysics Data System (ADS)

Mohamed, H. A.; Ali, H. M.; Mohamed, S. H.; Abd El-Raheem, M. M.

2006-04-01

Thin films of Zn{1-x} Cd{x}O with x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5 at.% were deposited by electron-beam evaporation technique. It has been found that, for as-deposited films, both the transmittance and electrical resistivity decreased with increasing the Cd content. To improve the optical and electrical properties of these films, the effect of annealing temperature and time were taken into consideration for Zn{1-x} Cd{x}O film with x = 0.2. It was found that, the optical transmittance and the electrical conductivity were improved significantly with increasing the time of annealing. At fixed temperature of 300 °C, the transmittance increased with increasing the time of annealing and reached its maximum values of 81% in the visible region and 94% in the NIR region at annealing time of 120 min. The low electrical resistivity of 3.6 × 10-3 Ω cm was achieved at the same conditions. Other parameters named free carrier concentrations, refractive index, extinction coefficient, plasma frequency, and relaxation time were studied as a function of annealing temperature and time for 20% Cd content.

Three stage vacuum system for ultralow temperature installation

NASA Astrophysics Data System (ADS)

Das, N. K.; Pradhan, J.; Naser, Md Z. A.; Mandal, B. Ch; Roy, A.; Kumar, P.; Mallik, C.; Bhandari, R. K.

2012-11-01

We use a three stage vacuum system for developing a dilution fridge at VECC, Kolkata. We aim at achieving a cooling power of 20μW at 100mK for various experiments especially in the field of condensed matter and nuclear physics. The system is essentially composed of four segments-bath cryostat, vacuum system, dilution insert and 3He circulation circuit. Requirement of vacuum system at different stages are different. The vacuum system for cryostat and for internal vacuum chamber located within the helium bath is a common turbo molecular pump backed by scroll pump as to maintain a vacuum ~10-6mbar. For bringing down the temperature of the helium evaporator, we use a high throughput Roots pump backed by a dry pump. The pumping system for 3He distillation chamber (still) requires a high pumping speed, so a turbo drag pump backed by a scroll pump has been installed. As the fridge use precious 3He gas for operation, the entire system has been made to be absolutely leak proof with respect to the 3He gas.

Control of stain geometry by drop evaporation of surfactant containing dispersions.

PubMed

Erbil, H Yildirim

2015-08-01

Control of stain geometry by drop evaporation of surfactant containing dispersions is an important topic of interest because it plays a crucial role in many applications such as forming templates on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials. This paper presents a review of the published articles on the diffusive drop evaporation of pure liquids (water), the surfactant stains obtained from evaporating drops that do not contain dispersed particles and deposits obtained from drops containing polymer colloids and carbon based particles such as carbon nanotubes, graphite and fullerenes. Experimental results of specific systems and modeling attempts are discussed. This review also has some special subtopics such as suppression of coffee-rings by surfactant addition and "stick-slip" behavior of evaporating nanosuspension drops. In general, the drop evaporation process of a surfactant/particle/substrate system is very complex since dissolved surfactants adsorb on both the insoluble organic/inorganic micro/nanoparticles in the drop, on the air/solution interface and on the substrate surface in different extends. Meanwhile, surfactant adsorbed particles interact with the substrate giving a specific contact angle, and free surfactants create a solutal Marangoni flow in the drop which controls the location of the particle deposition together with the rate of evaporation. In some cases, the presence of a surfactant monolayer at the air/solution interface alters the rate of evaporation. At present, the magnitude of each effect cannot be predicted adequately in advance and consequently they should be carefully studied for any system in order to control the shape and size of the final deposit. Copyright © 2014 Elsevier B.V. All rights reserved.

Infrared thermography of evaporative fluxes and dynamics of salt deposition on heterogeneous porous surfaces

NASA Astrophysics Data System (ADS)

Nachshon, Uri; Shahraeeni, Ebrahim; Or, Dani; Dragila, Maria; Weisbrod, Noam

2011-12-01

Evaporation of saline solutions from porous media, common in arid areas, involves complex interactions between mass transport, energy exchange and phase transitions. We quantified evaporation of saline solutions from heterogeneous sand columns under constant hydraulic boundary conditions to focus on effects of salt precipitation on evaporation dynamics. Mass loss measurements and infrared thermography were used to quantify evaporation rates. The latter method enables quantification of spatial and temporal variability of salt precipitation to identify its dynamic effects on evaporation. Evaporation from columns filled with texturally-contrasting sand using different salt solutions revealed preferential salt precipitation within the fine textured domains. Salt precipitation reduced evaporation rates from the fine textured regions by nearly an order of magnitude. In contrast, low evaporation rates from coarse-textured regions (due to low capillary drive) exhibited less salt precipitation and consequently less evaporation rate suppression. Experiments provided insights into two new phenomena: (1) a distinct increase in evaporation rate at the onset of evaporation; and (2) a vapor pumping mechanism related to the presence of a salt crust over semidry media. Both phenomena are related to local vapor pressure gradients established between pore water and the surface salt crust. Comparison of two salts: NaCl and NaI, which tend to precipitate above the matrix surface and within matrix pores, respectively, shows a much stronger influence of NaCl on evaporation rate suppression. This disparity reflects the limited effect of NaI precipitation on matrix resistivity for solution and vapor flows.

Correlation study of nanocrystalline carbon doped thin films prepared by a thermionic vacuum arc deposition technique

NASA Astrophysics Data System (ADS)

Dinca-Balan, Virginia; Vladoiu, Rodica; Mandes, Aurelia; Prodan, Gabriel

2017-11-01

The synthesis of Ag, Mg and Si nanocrystalline, embedded in a hydrogen-free amorphous carbon (a-C) matrix, deposited by a high vacuum and free buffer gas technique, were investigated. The films with compact structures and extremely smooth surfaces were prepared using the thermionic vacuum arc method in one electron gun configuration, on glass and silicon substrates. The surface morphology and wettability of the obtained multifunctional thin films were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and free surface energy (FSE) by See System. The results from the TEM measurements show how the Ag, Mg and Si interacted with carbon and the influence these materials have on the thin film structure formation and the grain size distribution. SEM correlated with EDX results reveal a very precise comparative study, regarding the quantity of the elements that morphed into carbides nanostructures. Also, the FSE results prove how different materials in combination with carbon can make changes to the surface properties.

Experimental investigation on the energy deposition and expansion rate under the electrical explosion of aluminum wire in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zongqian; Wang, Kun; Shi, Yuanjie

Experimental investigations on the electrical explosion of aluminum wire using negative polarity current in vacuum are presented. Current pulses with rise rates of 40 A/ns, 80 A/ns, and 120 A/ns are generated for investigating the influence of current rise rate on energy deposition. Experimental results show a significant increase of energy deposition into the wire before the voltage breakdown with the increase of current rise rate. The influence of wire dimension on energy deposition is investigated as well. Decreasing the wire length allows more energy to be deposited into the wire. The energy deposition of a 0.5 cm-long wire explosion ismore » ∼2.5 times higher than the energy deposition of a 2 cm-long wire explosion. The dependence of the energy deposition on wire diameter demonstrates a maximum energy deposition of 2.7 eV/atom with a diameter of ∼18 μm. Substantial increase in energy deposition is observed in the electrical explosion of aluminum wire with polyimide coating. A laser probe is applied to construct the shadowgraphy, schlieren, and interferometry diagnostics. The morphology and expansion trajectory of exploding products are analyzed based on the shadowgram. The interference phase shift is reconstructed from the interferogram. Parallel dual wires are exploded to estimate the expansion velocity of the plasma shell.« less

Study of titania nanorod films deposited by matrix-assisted pulsed laser evaporation as a function of laser fluence

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Belviso, M. R.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Luches, A.; Manera, M. G.; Martino, M.; Rella, R.; Taurino, A.

2011-11-01

Chemically synthesized brookite titanium dioxide (TiO2) nanorods with average diameter and length dimensions of 3-4 nm and 35-50 nm, respectively, were deposited by the matrix-assisted pulsed laser evaporation technique. A toluene nanorod solution was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser ( λ=248 nm, τ=20 ns) at the repetition rate of 10 Hz, at different fluences (25 to 350 mJ/cm2). The deposited films were structurally characterized by high-resolution scanning and transmission electron microscopy. <100> single-crystal Si wafers and carbon-coated Cu grids were used as substrates. Structural analyses evidenced the occurrence of brookite-phase crystalline nanospheres coexisting with individually distinguishable TiO2 nanorods in the films deposited at fluences varying from 50 to 350 mJ/cm2. Nanostructured TiO2 films comprising only nanorods were deposited by lowering the laser fluence to 25 mJ/cm2. The observed shape and phase transitions of the nanorods are discussed taking into account the laser-induced heating effects, reduced melting temperature and size-dependent thermodynamic stability of nanoscale TiO2.

Hole-transport material variation in fully vacuum deposited perovskite solar cells

NASA Astrophysics Data System (ADS)

Polander, Lauren E.; Pahner, Paul; Schwarze, Martin; Saalfrank, Matthias; Koerner, Christian; Leo, Karl

2014-08-01

This work addresses the effect of energy level alignment between the hole-transporting material and the active layer in vacuum deposited, planar-heterojunction CH3NH3PbIx-3Clx perovskite solar cells. Through a series of hole-transport materials, with conductivity values set using controlled p-doping of the layer, we correlate their ionization potentials with the open-circuit voltage of the device. With ionization potentials beyond 5.3 eV, a substantial decrease in both current density and voltage is observed, which highlights the delicate energetic balance between driving force for hole-extraction and maximizing the photovoltage. In contrast, when an optimal ionization potential match is found, the open-circuit voltage can be maximized, leading to power conversion efficiencies of up to 10.9%. These values are obtained with hole-transport materials that differ from the commonly used Spiro-MeO-TAD and correspond to a 40% performance increase versus this reference.

Thermodynamic performance testing of the orbiter flash evaporator system

NASA Technical Reports Server (NTRS)

Jaax, J. R.; Melgares, M. A.; Frahm, J. P.

1980-01-01

System level testing of the space shuttle orbiter's development flash evaporator system (FES) was performed in a thermal vacuum chamber capable of simulating ambient ascent, orbital, and entry temperature and pressure profiles. The test article included the evaporator assembly, high load and topping exhaust duct and nozzle assemblies, and feedwater supply assembly. Steady state and transient heat load, water pressure/temperature and ambient pressure/temperature profiles were imposed by especially designed supporting test hardware. Testing in 1978 verified evaporator and duct heater thermal design, determined FES performance boundaries, and assessed topping evaporator plume characteristics. Testing in 1979 combined the FES with the other systems in the orbiter active thermal control subsystem (ATCS). The FES met or exceeded all nominal and contingency performance requirements during operation with the integrated ATCS. During both tests stability problems were encountered during steady state operations which resulted in subsequent design changes to the water spray nozzle and valve plate assemblies.

A theoretical analysis of vacuum arc thruster performance

NASA Technical Reports Server (NTRS)

Polk, James E.; Sekerak, Mike; Ziemer, John K.; Schein, Jochen; Qi, Niansheng; Binder, Robert; Anders, Andre

2001-01-01

In vacuum arc discharges the current is conducted through vapor evaporated from the cathode surface. In these devices very dense, highly ionized plasmas can be created from any metallic or conducting solid used as the cathode. This paper describes theoretical models of performance for several thruster configurations which use vacuum arc plasma sources. This analysis suggests that thrusters using vacuum arc sources can be operated efficiently with a range of propellant options that gives great flexibility in specific impulse. In addition, the efficiency of plasma production in these devices appears to be largely independent of scale because the metal vapor is ionized within a few microns of the cathode electron emission sites, so this approach is well-suited for micropropulsion.

Sealing Materials for Use in Vacuum at High Temperatures

NASA Technical Reports Server (NTRS)

Pettit, Donald R.; Camarda, Charles J.; Lee Vaughn, Wallace

2012-01-01

Sealing materials that can be applied and left in place in vacuum over a wide range of temperatures (especially temperatures of a few thousand degrees Celsius) have been conceived and investigated for potential utility in repairing thermal-protection tiles on the space shuttles in orbit before returning to Earth. These materials are also adaptable to numerous terrestrial applications that involve vacuum processing and/or repair of structures that must withstand high temperatures. These materials can be formulated to have mechanical handling characteristics ranging from almost freely flowing liquid-like consistency through paste-like consistency to stiff puttylike consistency, and to retain these characteristics in vacuum until heated to high curing temperatures. A sealing material of this type can be formulated to be used in any of several different ways for example, to be impregnated into a high-temperature-fabric patch, impregnated into a high-temperature-fabric gasket for sealing a patch, applied under a patch, or applied alone in the manner of putty or wallboard compound. The sealing material must be formulated to be compatible with, and adhere to, the structural material(s) to be repaired. In general, the material consists of a vacuum-compatible liquid containing one or more dissolved compound(s) and/or mixed with suspended solid particles. Depending on the intended application, the liquid can be chosen to be of a compound that can remain in place in vacuum for a time long enough to be useful, and/or to evaporate or decompose in a controlled way to leave a useful solid residue behind. The evaporation rate is determined by proper choice of vapor pressure, application of heat, and/or application of ultraviolet light or other optical radiation. The liquid chosen for the original space shuttle application is a commercial silicone vacuum-pump oil.

Optical effect of the contamination of infrared windows by the outgassing of materials in outer space

NASA Technical Reports Server (NTRS)

Silberman, E.

1975-01-01

The products and kinetics of outgassing from S13G paint were studied by using infrared absorption measurements of the material outgassed (using an evaporation cell and vacuum chamber). Two separate long-term experimental depositions from heated samples of the S13G paint were made. Before each experiment, the vacuum chamber and sample holder were carefully cleaned and outgassed to ensure that subsequent deposits on the colled-window were due only to the products evaporated from the sample. Results of experiments are listed and discussed.

The "Hoover" (vacuum cleaner) technique for calcifying tendonitis deposits excision and removal of the calcific debris.

PubMed

Ehud, Atoun; Ehud, Rath; Alexander, Van Tongel; Ali, Narvani; Giusseppe, Sforza; Ofer, Levy

2012-07-01

A new technical tip for the improvement of the arthroscopic treatment of symptomatic calcifying tendinitis is described. Arthroscopic excision of calcifying tendonitis may result with multiple minute calcific debris in the subacromial bursa, causing severe post operative pain due to chemical irritation of the bursa. We suggest the use of a bladeless shaver barrel as a "Hoover" (vacuum cleaner) for arthroscopic clearance of these miniature calcific debris from the subacromial space after resection of the major deposits. The use of this technique resulted in good clinical outcome with improved post operative pain.

Research of vacuum polymer film on three-dimension surface (Conference Presentation)

NASA Astrophysics Data System (ADS)

Bau, Yung-Han

2016-09-01

This study focused on UV-curable acrylic hybrid of solute in vacuum-deposited on the surface and make it smooth. On the surface coating of the entire process, including the pre-treatment of organic solutes, vacuum, nozzle pressure, airflow, frequency ratio, the surface of the rotation rate, nozzle angle, UV light irradiation time, waste solute recycling.Organic solutes through a flow meter and precise measured,by high pressure or vibration of a piezoelectric material, spray our organic solute in a certain degree of vacuum,leaving nozzle of tiny micro-mist volatiles in a vacuum to form secondary atomization,deposited our surface,Since no UV light irradiation, the surface is a liquid having fluidity, so the non-planar substrates can have good performance, finally it is irradiated by UV light of sufficient energy solidify to form a solid film.The advantage of this approach is that a smooth surface,Strong adhesion, low-cost equipment, low temperature, a wide range of high deposition rate can be combined with other deposition method,Under vacuum have not waste because excess paint can be recycled.Avoid solute direct contact with human, relative to the environment-friendly.

Vacuum deposited optical coatings experiment (AO 138-4)

NASA Technical Reports Server (NTRS)

Charlier, Jean

1991-01-01

The aim of this experiment was to test the optical behavior of 20 components and coatings subjected to space exposure. Most of them are commonly used for their reflective or transmittive properties in spaceborne optics. They consist in several kind of metallic and dielectric mirrors designed for the 0.12 to 10 microns spectrum, UV, and NIR bandpass filters, visible, and IR antireflecting coatings, visible/IR dichroic beam splitters, and visible beam splitter. The coatings were deposited on various substrates such as glasses, germanium, magnesium fluoride, quartz, zinc selenide, and kanigened aluminum. Several coating materials were used such as Al, Ag, Au, MgF2, LaF3, ThF3, ThF4, SiO2, TiO2, ZrO2, Al2O3, MgO, Ge, and ZnSe. Five samples of each component were manufactured. Two flight samples were mounted in such a way that one was directly exposed to space and the other looking backwards. The same arrangement was used for the spare samples stored on ground in a box identical to the flight one and they were kept under vacuum during the LDEF mission. Finally, one set of reference components was stocked in a sealed box under a dry nitrogen atmosphere. By comparing the preflight and postflight optical performances of the five samples of each component, it is possible to detect the degradations due to the space exposure.

Thermoelectric integrated membrane evaporation water recovery technology

NASA Technical Reports Server (NTRS)

Roebelen, G. J., Jr.; Winkler, H. E.; Dehner, G. F.

1982-01-01

The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

Deposit heterogeneity and the dynamics of the organic semiconductors P3HT and PCBM solution under evaporation

NASA Astrophysics Data System (ADS)

Yu, H. P.; Luo, H.; Liu, T. T.; Jing, G. Y.

2015-04-01

The formation of organic semiconductor layer is the key procedure in the manufacture of organic photovoltaic solar cell, in which the natural evaporation of the solvent from the polymer solution plays the essential role for the conversion efficiency. Here, poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as two types of semiconductor polymers, were selected as the active layer to form the deposit by drying the blend solution drops on the substrate. We explored the influences of droplet size and solute concentration on the homogeneity of the deposit. Additionally, the spatial distribution of molecular chains and grains and the instability of the droplet morphology during the drying were investigated. The results showed that the "coffee-ring" phenomenon occurred forming an annular deposit at the outermost edge and the width of the annular ring increased linearly with the concentration of the P3HT solution, until a saturation plateau is approached. On the other hand, the PCBM deposition presented a circular disk at low concentration, but displayed a sudden instability for an irregular perimeter at a critical concentration and there existed a second critical concentration above which the deposit exhibited the return of the stable circular shape. The results have an instructive impact on the performance of the device and the formation of fine structures during the process of printing, film preparation and painting.

Vapor pressures and evaporation coefficients for melts of ferromagnesian chondrule-like compositions

NASA Astrophysics Data System (ADS)

Fedkin, A. V.; Grossman, L.; Ghiorso, M. S.

2006-01-01

To determine evaporation coefficients for the major gaseous species that evaporate from silicate melts, the Hertz-Knudsen equation was used to model the compositions of residues of chondrule analogs produced by evaporation in vacuum by Hashimoto [Hashimoto A. (1983) Evaporation metamorphism in the early solar nebula-evaporation experiments on the melt FeO-MgO-SiO 2-CaO-Al 2O 3 and chemical fractionations of primitive materials. Geochem. J. 17, 111-145] and Wang et al. [Wang J., Davis A. M., Clayton R. N., Mayeda T. K., Hashimoto A. (2001) Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO 2-CaO-Al 2O 3-TiO 2 rare earth element melt system. Geochim. Cosmochim. Acta 65, 479-494], in vacuum and in H 2 by Yu et al. [Yu Y., Hewins R. H., Alexander C. M. O'D., Wang J. (2003) Experimental study of evaporation and isotopic mass fractionation of potassium in silicate melts. Geochim. Cosmochim. Acta 67, 773-786], and in H 2 by Cohen et al. [Cohen B. A., Hewins R. H., Alexander C. M. O'D. (2004) The formation of chondrules by open-system melting of nebular condensates. Geochim. Cosmochim. Acta 68, 1661-1675]. Vapor pressures were calculated using the thermodynamic model of Ghiorso and Sack [Ghiorso M. S., Sack R. O. (1995) Chemical mass transfer in magmatic processes IV. A revised and internally consistent thermodynamic model for the interpolation and extrapolation of liquid-solid equilibria in magmatic systems at elevated temperatures and pressures. Contrib. Mineral. Petrol. 119, 197-212], except for the late, FeO-free stages of the Wang et al. (2001) and Cohen et al. (2004) experiments, where the CMAS activity model of Berman [Berman R. G. (1983) A thermodynamic model for multicomponent melts, with application to the system CaO-MgO-Al 2O 3-SiO 2. Ph.D. thesis, University of British Columbia] was used. From these vapor pressures, evaporation coefficients ( α) were obtained that give the best fits to the time variation of the residue compositions

Thin-film encapsulation of organic electronic devices based on vacuum evaporated lithium fluoride as protective buffer layer

NASA Astrophysics Data System (ADS)

Peng, Yingquan; Ding, Sihan; Wen, Zhanwei; Xu, Sunan; Lv, Wenli; Xu, Ziqiang; Yang, Yuhuan; Wang, Ying; Wei, Yi; Tang, Ying

2017-03-01

Encapsulation is indispensable for organic thin-film electronic devices to ensure reliable operation and long-term stability. For thin-film encapsulating organic electronic devices, insulating polymers and inorganic metal oxides thin films are widely used. However, spin-coating of insulating polymers directly on organic electronic devices may destroy or introduce unwanted impurities in the underlying organic active layers. And also, sputtering of inorganic metal oxides may damage the underlying organic semiconductors. Here, we demonstrated that by utilizing vacuum evaporated lithium fluoride (LiF) as protective buffer layer, spin-coated insulating polymer polyvinyl alcohol (PVA), and sputtered inorganic material Er2O3, can be successfully applied for thin film encapsulation of copper phthalocyanine (CuPc)-based organic diodes. By encapsulating with LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films, the device lifetime improvements of 10 and 15 times can be achieved. These methods should be applicable for thin-film encapsulation of all kinds of organic electronic devices. Moisture-induced hole trapping, and Al top electrode oxidation are suggest to be the origins of current decay for the LiF/PVA/LiF trilayer and LiF/Er2O3 bilayer films encapsulated devices, respectively.

Vacuum distillation/vapor filtration water recovery, phases 1 and 2

NASA Technical Reports Server (NTRS)

Honegger, R. J.; Remus, G. A.; Krug, E. K.

1973-01-01

The research is reported on the development of an evaporator for vacuum distillation/vapor filtration VD/VF water reclamation system for use on manned space flights. The design, fabrication, and tests of a six-man evaporator are described. It is concluded that: (1) A condenser with an internal rotating impeller and coolant surfaces directly opposite the condensing surfaces is an effective condenser. (2) The VD/VF evaporator, catalyst unit and condenser function satisfactorily based on thermal, mechanical and recovery performance during a 145-hour evaluation test. (3) The quality of recovered water, as measured by analyses for total organic carbon, pH, conductivity, turbidity, and viable bacteria density was within established limits for potability.

IZO deposited by PLD on flexible substrate for organic heterostructures

NASA Astrophysics Data System (ADS)

Socol, M.; Preda, N.; Stanculescu, A.; Breazu, C.; Florica, C.; Rasoga, O.; Stanculescu, F.; Socol, G.

2017-05-01

In:ZnO (IZO) thin films were deposited on flexible plastic substrates by pulsed laser deposition (PLD) method. The obtained layers present adequate optical and electrical properties competitive with those based on indium tin oxide (ITO). The figure of merit (9 × 10-3 Ω-1) calculated for IZO layers demonstrates that high quality coatings can be prepared by this deposition technique. A thermal annealing (150 °C for 1 h) or an oxygen plasma etching (6 mbar for 10 min.) were applied to the IZO layers to evaluate the influence of these treatments on the properties of the transparent coatings. Using vacuum evaporation, organic heterostructures based on cooper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) were deposited on the untreated and treated IZO layers. The optical and electrical properties of the heterostructures were investigated by UV-Vis, FTIR and current-voltage ( I- V) measurements. For the heterostructure fabricated on IZO treated in oxygen plasma, an improvement in the current value with at least one order of magnitude was evidenced in the I- V characteristics recorded in dark conditions. Also, an increase in the current value for the heterostructure deposited on untreated IZO layer can be achieved by adding an organic layer such as tris-8-hydroxyquinoline aluminium (Alq3).

Membrane-Based Water Evaporator for a Space Suit

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.; McCann, Charles J.; O'Connell, Mary K.; Andrea, Scott

2004-01-01

A membrane-based water evaporator has been developed that is intended to serve as a heat-rejection device for a space suit. This evaporator would replace the current sublimator that is sensitive to contamination of its feedwater. The design of the membrane-based evaporator takes advantage of recent advances in hydrophobic micropore membranes to provide robust heat rejection with much less sensitivity to contamination. The low contamination sensitivity allows use of the heat transport loop as feedwater, eliminating the need for the separate feedwater system used for the sublimator. A cross section of the evaporator is shown in the accompanying figure. The space-suit cooling loop water flows into a distribution plenum, through a narrow annulus lined on both sides with a hydrophobic membrane, into an exit plenum, and returns to the space suit. Two perforated metal tubes encase the membranes and provide structural strength. Evaporation at the membrane inner surface dissipates the waste heat from the space suit. The water vapor passes through the membrane, into a steam duct and is vented to the vacuum environment through a back-pressure valve. The back-pressure setting can be adjusted to regulate the heat-rejection rate and the water outlet temperature.

Evaporation-Driven Deposition of ITO Thin Films from Aqueous Solutions with Low-Speed Dip-Coating Technique.

PubMed

Ito, Takashi; Uchiyama, Hiroaki; Kozuka, Hiromitsu

2017-05-30

We suggest a novel wet coating process for preparing indium tin oxide (ITO) films from simple solutions containing only metal salts and water via evaporation-driven film deposition during low-speed dip coating. Homogeneous ITO precursor films were deposited on silica glass substrates from the aqueous solutions containing In(NO 3 ) 3 ·3H 2 O and SnCl 4 ·5H 2 O by dip coating at substrate withdrawal speeds of 0.20-0.50 cm min -1 and then crystallized by the heat treatment at 500-800 °C for 10-60 min under N 2 gas flow of 0.5 L min -1 . The ITO films heated at 600 °C for 30 min had a high optical transparency in the visible range and a good electrical conductivity. Multiple-coating ITO films obtained with five-times dip coating exhibited the lowest sheet (ρ S ) and volume (ρ V ) resistivities of 188 Ω sq -1 and 4.23 × 10 -3 Ω cm, respectively.

Evaporative cooling of microscopic water droplets in vacuo: Molecular dynamics simulations and kinetic gas theory

DOE PAGES

Schlesinger, Daniel; Sellberg, Jonas A.; Nilsson, Anders; ...

2016-03-22

In the present study, we investigate the process of evaporative cooling of nanometer-sized droplets in vacuum using molecular dynamics simulations with the TIP4P/2005 water model. The results are compared to the temperature evolution calculated from the Knudsen theory of evaporation which is derived from kinetic gas theory. The calculated and simulation results are found to be in very good agreement for an evaporation coefficient equal to unity. Lastly, our results are of interest to experiments utilizing droplet dispensers as well as to cloud micro-physics.

Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop

NASA Astrophysics Data System (ADS)

Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, J. G. M.; Zhang, Xuehua; Lohse, Detlef

2016-11-01

Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Here we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called "Ouzo effect." Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, in phase IV, all water has evaporated, leaving behind a tiny spherical cap-shaped oil drop.

Evaporation dynamics of a sessile droplet on glass surfaces with fluoropolymer coatings: focusing on the final stage of thin droplet evaporation.

PubMed

Gatapova, Elizaveta Ya; Shonina, Anna M; Safonov, Alexey I; Sulyaeva, Veronica S; Kabov, Oleg A

2018-03-07

The evaporation dynamics of a water droplet with an initial volume of 2 μl from glass surfaces with fluoropolymer coatings are investigated using the shadow technique and an optical microscope. The droplet profile for a contact angle of less than 5° is constructed using an image-analyzing interference technique, and evaporation dynamics are investigated at the final stage. We coated the glass slides with a thin film of a fluoropolymer by the hot-wire chemical vapor deposition method at different deposition modes depending on the deposition pressure and the temperature of the activating wire. The resulting surfaces have different structures affecting the wetting properties. Droplet evaporation from a constant contact radius mode in the early stage of evaporation was found followed by the mode where both contact angle and contact radius simultaneously vary in time (final stage) regardless of wettability of the coated surfaces. We found that depinning occurs at small contact angles of 2.2-4.7° for all samples, which are smaller than the measured receding contact angles. This is explained by imbibition of the liquid into the developed surface of the "soft" coating that leads to formation of thin droplets completely wetting the surface. The final stage, which is little discussed in the literature, is also recorded. We have singled out a substage where the contact line velocity is abruptly increasing for all coated and uncoated surfaces. The critical droplet height corresponding to the transition to this substage is about 2 μm with R/h = 107. The duration of this substage is the same for all coated and uncoated surfaces. Droplets observed at this substage for all the tested surfaces are axisymmetric. The specific evaporation rate clearly demonstrates an abrupt increase at the final substage of the droplet evaporation. The classical R 2 law is justified for the complete wetting situation where the droplet is disappearing in an axisymmetric manner.

Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop.

PubMed

Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, J G M; Zhang, Xuehua; Lohse, Detlef

2016-08-02

Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Whereas the evaporation of pure liquids, liquids with dispersed particles, or even liquid mixtures has intensively been studied over the past two decades, the evaporation of ternary mixtures of liquids with different volatilities and mutual solubilities has not yet been explored. Here we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life-a transparent mixture of water, ethanol, and anise oil) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called "Ouzo effect." Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, in phase IV, all water has evaporated, leaving behind a tiny spherical cap-shaped oil drop.

Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop

NASA Astrophysics Data System (ADS)

Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, J. G. M.; Zhang, Xuehua; Lohse, Detlef

2016-08-01

Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Whereas the evaporation of pure liquids, liquids with dispersed particles, or even liquid mixtures has intensively been studied over the past two decades, the evaporation of ternary mixtures of liquids with different volatilities and mutual solubilities has not yet been explored. Here we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life—a transparent mixture of water, ethanol, and anise oil) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called “Ouzo effect.” Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, in phase IV, all water has evaporated, leaving behind a tiny spherical cap-shaped oil drop.

Evaporation-triggered microdroplet nucleation and the four life phases of an evaporating Ouzo drop

PubMed Central

Tan, Huanshu; Diddens, Christian; Lv, Pengyu; Kuerten, J. G. M.; Zhang, Xuehua; Lohse, Detlef

2016-01-01

Evaporating liquid droplets are omnipresent in nature and technology, such as in inkjet printing, coating, deposition of materials, medical diagnostics, agriculture, the food industry, cosmetics, or spills of liquids. Whereas the evaporation of pure liquids, liquids with dispersed particles, or even liquid mixtures has intensively been studied over the past two decades, the evaporation of ternary mixtures of liquids with different volatilities and mutual solubilities has not yet been explored. Here we show that the evaporation of such ternary mixtures can trigger a phase transition and the nucleation of microdroplets of one of the components of the mixture. As a model system, we pick a sessile Ouzo droplet (as known from daily life—a transparent mixture of water, ethanol, and anise oil) and reveal and theoretically explain its four life phases: In phase I, the spherical cap-shaped droplet remains transparent while the more volatile ethanol is evaporating, preferentially at the rim of the drop because of the singularity there. This leads to a local ethanol concentration reduction and correspondingly to oil droplet nucleation there. This is the beginning of phase II, in which oil microdroplets quickly nucleate in the whole drop, leading to its milky color that typifies the so-called “Ouzo effect.” Once all ethanol has evaporated, the drop, which now has a characteristic nonspherical cap shape, has become clear again, with a water drop sitting on an oil ring (phase III), finalizing the phase inversion. Finally, in phase IV, all water has evaporated, leaving behind a tiny spherical cap-shaped oil drop. PMID:27418601

Development and parametric evaluation of the prototype 2 and 3 flash evaporators

NASA Technical Reports Server (NTRS)

Hixon, C. W.; Dietz, J. B.

1975-01-01

Development of the Prototype 2 and 3 flash evaporator heat sinks which vaporize an expendable fluid to cool a heat transport fluid loop is reported. The units utilize Freon 21 as the heat transport fluid and water as the expendable fluid to meet the projected performance requirements of the space shuttle for both on-orbit and ascent/reentry operations. The evaporant is pulse-sprayed by on-off control onto heat transfer surfaces containing the transport fluid and exhausted to the vacuum environment through fixed area exhaust ducts.

Mimicking Martian dust: An in-vacuum dust deposition system for testing the ultraviolet sensors on the Curiosity rover.

PubMed

Sobrado, J M; Martín-Soler, J; Martín-Gago, J A

2015-10-01

We have designed and developed an in-vacuum dust deposition system specifically conceived to simulate and study the effect of accumulation of Martian dust on the electronic instruments of scientific planetary exploration missions. We have used this device to characterize the dust effect on the UV sensor of the Rover Environmental Monitoring Station in the Mars science Laboratory mission of NASA in similar conditions to those found on Mars surface. The UV sensor includes six photodiodes for measuring the radiation in all UV wavelengths (direct incidence and reflected); it is placed on the body of Curiosity rover and it is severely affected by the dust deposited on it. Our experimental setup can help to estimate the duration of reliable reading of this instrument during operation. We have used an analogous of the Martian dust in chemical composition (magnetic species), color, and density, which has been characterized by X-ray spectroscopy. To ensure a Brownian motion of the dust during its fall and a homogeneous coverage on the instrumentation, the operating conditions of the vacuum vessel, determined by partial pressures and temperature, have to be modified to account for the different gravities of Mars with respect to Earth. We propose that our designed device and operational protocol can be of interest to test optoelectronic instrumentation affected by the opacity of dust, as can be the degradation of UV photodiodes in planetary exploration.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, Gordon E.

1998-01-01

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Design of evaporator of spacelab refrigerator/freezer

NASA Technical Reports Server (NTRS)

Hye, A.

1985-01-01

An Evaporator has been designed for NASA-Johnson Space Center Life Sciences to conduct experiments in Spacelab mission SLS-1 using different samples such as blood, urine, human tissues etc. Two units will fly - one as a Refrigerator (4 C) and the other as a Freezer (-22 C). The evaporator tube is dip brazed on a grooved flat plate. Aluminum heat sink is dip brazed on the other side of the plate. Freon R5O2 is pumped through the tube and air is circulated over the finned surface to transfer heat. As freon 5O2 is considered toxic, the whole freon tube is covered with an evaporator cover to contain any freon leakage to avoid exposure to crew members. This containment is under vacuum and this pressure is monitored along with the freon pressure to determine freon leakage so that necessary steps can be taken to stop contamination of the spacelab air. An stress analysis has been done and it is found to have adequate safety margin to meet the requirements of NASA safety and reliability standards.

Production and characterization of thin film group IIIB, IVB and rare earth hydrides by reactive evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Provo, James L., E-mail: jlprovo@verizon.net

2015-07-15

A recent short history of reactive evaporation by D. M. Mattox [History Corner—A Short History of Reactive Evaporation, SVC Bulletin (Society of Vacuum Coaters, Spring 2014), p. 50–51] describes various methods for producing oxides, nitrides, carbides, and some compounds, but hydrides were not mentioned. A study was performed in the mid-1970s at the General Electric Company Neutron Devices Department in Largo, FL, by the author to study preparation of thin film hydrides using reactive evaporation and to determine their unique characteristics and properties. Films were produced of scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), and the rare earth praseodymiummore » (Pr), neodymium (Nd), gadolinium (Gd), dysprosium (Dy), and erbium (Er) hydrides by hot crucible filament and electron beam evaporation in atmospheres of deuterium and tritium gases. All-metal vacuum systems were used and those used with tritium were dedicated for this processing. Thin film test samples 1000 nm thick were prepared on 1.27 cm diameter molybdenum disk substrates for each occluder (i.e., an element that can react with hydrogen to form a hydride) material. Loading characteristics as determined by gas-to-metal atomic ratios, oxidation characteristics as determined by argon–sputter Auger analysis, film structure as determined by scanning electron microscope analysis, and film stress properties as determined by a double resonator technique were used to define properties of interest. Results showed hydrogen-to-metal atomic ratios varied from 1.5 to 2.0 with near maximum loading for all but Pr and Nd occluders which correlated with the oxidation levels observed, with all occluder oxidation levels being variable due to vacuum system internal processing conditions and the materials used. Surface oxide levels varied from ∼80 Å to over 1000 Å. For most films studied, results showed that a maximum loading ratio of near 2.0 and a minimum surface oxide level of ∼80�

Cleaner Vacuum-Bag Curing

NASA Technical Reports Server (NTRS)

Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.

1987-01-01

Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.

Enhanced vacuum arc vapor deposition electrode

NASA Technical Reports Server (NTRS)

Weeks, Jack L. (Inventor); Todd, Douglas M. (Inventor)

1999-01-01

A process for forming a thin metal coating on a substrate wherein a gas stream heated by an electrical current impinges on a metallic target in a vacuum chamber to form a molten pool of the metal and then vaporize a portion of the pool, with the source of the heated gas stream being on one side of the target and the substrate being on the other side of the target such that most of the metallic vapor from the target is directed at the substrate.

Ultralight Fabric Reflux Tube (UFRT) Thermal/Vacuum Test

NASA Technical Reports Server (NTRS)

Hurlbert, K. M.; Ewert, M. K.; Graf, J. P.; Keller, J. R.; Pauley, K. A.; Guenther, R. J.; Antoniak, Z. I.

1996-01-01

Spacecraft thermal control systems are essential to provide the necessary environment for the crew and equipment to function adequately on space missions. The Ultralight Fabric Reflux Tube (UFRT) was developed by Pacific Northwest Laboratory (PNL) as a lightweight radiator concept to be used on planetary-type missions (e.g., Moon, Mars). The UFRT consists of a thin-walled tube (acting as the fluid boundary), overwrapped with a low-mass ceramic fabric (acting as the primary pressure boundary). The tubes are placed in an array in the vertical position with the evaporators at the lower end. Heat is added to the evaporators, which vaporizes the working fluid. The vapor travels to the condenser end above and cools as heat is radiated to the environment. The fluid condensed on the tube wall is then returned to the evaporator by gravity. The primary objectives for the fiscal year 1994 program included the design and fabrication of prototype UFRTs and thermal/vacuum chamber testing of these test articles. Six UFRTS, with improved titanium liners, were successfully manufactured and provided to the Johnson Space Center in July 1994. Five were tested in a thermal/vacuum chamber in September 1994. Data obtained to characterize the performance of the UFRTs under simulated lunar conditions demonstrated the design concept successfully. In addition, a trade study showed that an optimized/improved UFRT could achieve as much as a 25% mass savings in the heat rejection subsystem of future planetary-type thermal control systems.

Dynamics and universal scaling law in geometrically-controlled sessile drop evaporation

PubMed Central

Sáenz, P. J.; Wray, A. W.; Che, Z.; Matar, O. K.; Valluri, P.; Kim, J.; Sefiane, K.

2017-01-01

The evaporation of a liquid drop on a solid substrate is a remarkably common phenomenon. Yet, the complexity of the underlying mechanisms has constrained previous studies to spherically symmetric configurations. Here we investigate well-defined, non-spherical evaporating drops of pure liquids and binary mixtures. We deduce a universal scaling law for the evaporation rate valid for any shape and demonstrate that more curved regions lead to preferential localized depositions in particle-laden drops. Furthermore, geometry induces well-defined flow structures within the drop that change according to the driving mechanism. In the case of binary mixtures, geometry dictates the spatial segregation of the more volatile component as it is depleted. Our results suggest that the drop geometry can be exploited to prescribe the particle deposition and evaporative dynamics of pure drops and the mixing characteristics of multicomponent drops, which may be of interest to a wide range of industrial and scientific applications. PMID:28294114

Dynamics and universal scaling law in geometrically-controlled sessile drop evaporation.

PubMed

Sáenz, P J; Wray, A W; Che, Z; Matar, O K; Valluri, P; Kim, J; Sefiane, K

2017-03-15

The evaporation of a liquid drop on a solid substrate is a remarkably common phenomenon. Yet, the complexity of the underlying mechanisms has constrained previous studies to spherically symmetric configurations. Here we investigate well-defined, non-spherical evaporating drops of pure liquids and binary mixtures. We deduce a universal scaling law for the evaporation rate valid for any shape and demonstrate that more curved regions lead to preferential localized depositions in particle-laden drops. Furthermore, geometry induces well-defined flow structures within the drop that change according to the driving mechanism. In the case of binary mixtures, geometry dictates the spatial segregation of the more volatile component as it is depleted. Our results suggest that the drop geometry can be exploited to prescribe the particle deposition and evaporative dynamics of pure drops and the mixing characteristics of multicomponent drops, which may be of interest to a wide range of industrial and scientific applications.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, G.E.

1998-03-10

A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

Cold cathode vacuum discharge tube

DOEpatents

Boettcher, G.E.

1998-04-14

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

Effect of non-vacuum thermal annealing on high indium content InGaN films deposited by pulsed laser deposition.

PubMed

Wang, Tzu-Yu; Ou, Sin-Liang; Shen, Kun-Ching; Wuu, Dong-Sing

2013-03-25

InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications.

Ultrahigh vacuum process for the deposition of nanotubes and nanowires

DOEpatents

Das, Biswajit; Lee, Myung B

2015-02-03

A system and method A method of growing an elongate nanoelement from a growth surface includes: a) cleaning a growth surface on a base element; b) providing an ultrahigh vacuum reaction environment over the cleaned growth surface; c) generating a reactive gas of an atomic material to be used in forming the nanoelement; d) projecting a stream of the reactive gas at the growth surface within the reactive environment while maintaining a vacuum of at most 1.times.10.sup.-4 Pascal; e) growing the elongate nanoelement from the growth surface within the environment while maintaining the pressure of step c); f) after a desired length of nanoelement is attained within the environment, stopping direction of reactive gas into the environment; and g) returning the environment to an ultrahigh vacuum condition.

Influence of three different concentration techniques on evaporation rate, color and phenolics content of blueberry juice.

PubMed

Elik, Aysel; Yanık, Derya Koçak; Maskan, Medeni; Göğüş, Fahrettin

2016-05-01

The present study was undertaken to assess the effects of three different concentration processes open-pan, rotary vacuum evaporator and microwave heating on evaporation rate, the color and phenolics content of blueberry juice. Kinetics model study for changes in soluble solids content (°Brix), color parameters and phenolics content during evaporation was also performed. The final juice concentration of 65° Brix was achieved in 12, 15, 45 and 77 min, for microwave at 250 and 200 W, rotary vacuum and open-pan evaporation processes, respectively. Color changes associated with heat treatment were monitored using Hunter colorimeter (L*, a* and b*). All Hunter color parameters decreased with time and dependently studied concentration techniques caused color degradation. It was observed that the severity of color loss was higher in open-pan technique than the others. Evaporation also affected total phenolics content in blueberry juice. Total phenolics loss during concentration was highest in open-pan technique (36.54 %) and lowest in microwave heating at 200 W (34.20 %). So, the use of microwave technique could be advantageous in food industry because of production of blueberry juice concentrate with a better quality and short time of operation. A first-order kinetics model was applied to modeling changes in soluble solids content. A zero-order kinetics model was used to modeling changes in color parameters and phenolics content.

Wetting and evaporation of salt-water nanodroplets: A molecular dynamics investigation.

PubMed

Zhang, Jun; Borg, Matthew K; Sefiane, Khellil; Reese, Jason M

2015-11-01

We employ molecular dynamics simulations to study the wetting and evaporation of salt-water nanodroplets on platinum surfaces. Our results show that the contact angle of the droplets increases with the salt concentration. To verify this, a second simulation system of a thin salt-water film on a platinum surface is used to calculate the various surface tensions. We find that both the solid-liquid and liquid-vapor surface tensions increase with salt concentration and as a result these cause an increase in the contact angle. However, the evaporation rate of salt-water droplets decreases as the salt concentration increases, due to the hydration of salt ions. When the water molecules have all evaporated from the droplet, two forms of salt crystals are deposited, clump and ringlike, depending on the solid-liquid interaction strength and the evaporation rate. To form salt crystals in a ring, it is crucial that there is a pinned stage in the evaporation process, during which salt ions can move from the center to the rim of the droplets. With a stronger solid-liquid interaction strength, a slower evaporation rate, and a higher salt concentration, a complete salt crystal ring can be deposited on the surface.

Producing carbon stripper foils containing boron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoner, J. O. Jr.

2012-12-19

Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

Evaporation of Nanosuspensions on Substrates with Different Hydrophobicity.

PubMed

Perrin, Lionel; Pajor-Swierzy, Anna; Magdassi, Shlomo; Kamyshny, Alexander; Ortega, Francisco; Rubio, Ramón G

2018-01-24

Liquid drop evaporation on surfaces is present in many industrial and medical applications, e.g., printed electronics, spraying of pesticides, DNA mapping, etc. Despite this strong interest, a theoretical description of the dynamic of the evaporation of complex liquid mixtures and nanosuspensions is still lacking. Indeed, one of the aspects that have not been included in the current theoretical descriptions is the competition between the kinetics of evaporation and the adsorption of surfactants and/or particles at the liquid/vapor and liquid/solid interfaces. Materials formed by an electrically isolating solid on which a patterned conducting layer was formed by the deposits left after drop evaporation have been considered as very promising for building electrical circuits on flexible plastic substrates. In this work, we have done an exhaustive study of the evaporation of nanosuspensions of latex and hydrophobized silver nanoparticles on four substrates of different hydrophobicity. The advancing and receding contact angles as well as the time dependence of the volume of the droplets have been measured over a broad range of particle concentrations. Also, mixtures of silver particles and a surfactant, commonly used in industrial printing, have been examined. Furthermore, the adsorption kinetics at both the air/liquid and solid/liquid interfaces have been measured. Whereas the latex particles do not adsorb at the solid/liquid and only slightly reduce the surface tension, the silver particles strongly adsorb at both interfaces. The experimental results of the evaporation process were compared with the predictions of the theory of Semenov et al. (Evaporation of Sessile Water Droplets: Universal Behavior in the Presence of Contact Angle Hysteresis. Colloids Surf. Physicochem. Eng. Asp. 2011, 391 (1-3), 135-144) and showed surprisingly good agreement despite that the theory was developed for pure liquids. The morphology of the deposits left by the droplets after total

Characteristics of the Self-evaporation Behavior of Sprinkled Water near the Triple Point

NASA Astrophysics Data System (ADS)

Aizawa, Kazuo; Hayashi, Kanetoshi; Ogoshi, Hidemasa; Maeyama, Katsuya; Yonezawa, Noriyuki

For the sake of capturing the basic data in concern with the designing of vacuum evaporation apparatus, characteristics of the self-evaporation behavior of sprinkled water near the triple point has been investigated experimentally. The relationship between the amount of the vaporized water and the pressure in the vessel was elucidated quantitatively on the condition that over-heated water was sprinkled from water supplying nozzles of diameter of 4 mm into the center of the steam area in the heat insulation glass evaporation vessel having diameter of 200 mm and height of 1100 mm. Even under the mild water sprinkling conditions such as no small particle formation, small Reynolds number, and small Weber number, the temperature effectiveness of the self-evaporation in the center of the steam was as high as 80%, which clearly shows the effectiveness of this water-sprinkling method. In addition, the basic data for system designing such as water evaporation coefficient from water layer surface and temperature effectiveness of self-evaporation during the f1ight in the steam space were obtained.

Mimicking Martian dust: An in-vacuum dust deposition system for testing the ultraviolet sensors on the Curiosity rover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobrado, J. M., E-mail: sobradovj@inta.es; Martín-Soler, J.; Martín-Gago, J. A.

We have designed and developed an in-vacuum dust deposition system specifically conceived to simulate and study the effect of accumulation of Martian dust on the electronic instruments of scientific planetary exploration missions. We have used this device to characterize the dust effect on the UV sensor of the Rover Environmental Monitoring Station in the Mars science Laboratory mission of NASA in similar conditions to those found on Mars surface. The UV sensor includes six photodiodes for measuring the radiation in all UV wavelengths (direct incidence and reflected); it is placed on the body of Curiosity rover and it is severelymore » affected by the dust deposited on it. Our experimental setup can help to estimate the duration of reliable reading of this instrument during operation. We have used an analogous of the Martian dust in chemical composition (magnetic species), color, and density, which has been characterized by X-ray spectroscopy. To ensure a Brownian motion of the dust during its fall and a homogeneous coverage on the instrumentation, the operating conditions of the vacuum vessel, determined by partial pressures and temperature, have to be modified to account for the different gravities of Mars with respect to Earth. We propose that our designed device and operational protocol can be of interest to test optoelectronic instrumentation affected by the opacity of dust, as can be the degradation of UV photodiodes in planetary exploration.« less

Columnar-thin-film acquisition of fingerprint topology

NASA Astrophysics Data System (ADS)

Shaler, Robert C.; Lakhtakia, Akhlesh; Rogers, Jessica W.; Pulsifer, Drew P.; Martín-Palma, Raúl J.

2011-01-01

Fingerprint visualization obtained from physical evidence taken from crime scenes for subsequent comparison typically requires the use of physical and chemical techniques. One physical technique to visualize or develop sebaceous fingerprints on various surfaces employs the deposition of metals such as gold and zinc thereon. We have developed a different vacuum technology: the conformal-evaporated-film-by-rotation technique to deposit dense columnar thin films (CTFs) on latent fingerprints on different types of surfaces. Sample fingerprints, acting as nonplanar substrates, deposited on different surfaces were placed in a vacuum chamber with the fingerprint side facing a boat containing an evaporant material such as chalcogenide glass. Thermal evaporation of the solid material led to the formation of a dense CTF on the fingerprint, thereby capturing the topographical texture with high resolution. Our results show that it is possible to acquire the topology of latent fingerprints on nonporous surfaces. Additionally, deposition of CTFs on overlapping fingerprints suggested ours may be a technique for elucidating the sequence of deposition of the fingerprints at the scene.

Columnar-thin-film acquisition of fingermark topology

NASA Astrophysics Data System (ADS)

Shaler, Robert C.; Lakhtakia, Akhlesh; Rogers, Jessica W.; Pulsifer, Drew P.; Martín-Palma, Raúl J.

2010-08-01

Fingerprint visualization obtained from physical evidence taken from crime scenes for subsequent comparison typically requires the use of physical and chemical techniques. One physical technique to visualize or develop sebaceous fingerprints on various surfaces employs the deposition of metals such as gold and zinc thereon. We have developed a different vacuum technology: the conformal-evaporated-film-by-rotation technique to deposit dense columnar thin films (CTFs) on latent fingerprints on different types of surfaces. Sample fingerprints, acting as nonplanar substrates, deposited on different surfaces were placed in a vacuum chamber with the fingerprint side facing a boat containing an evaporant material such as chalcogenide glass. Thermal evaporation of the solid material led to the formation of a dense CTF on the fingerprint, thereby capturing the topographical texture with high resolution. Our results show that it is possible to acquire the topology of latent fingerprints on non-porous surfaces. Additionally, deposition of CTFs on overlapping fingerprints suggested ours may be a technique for elucidating the sequence of deposition of the fingerprints at the scene.

Synthesis, characterization and application of functional carbon nano materials

NASA Astrophysics Data System (ADS)

Chu, Jin

The synthesis, characterizations and applications of carbon nanomaterials, including carbon nanorods, carbon nanosheets, carbon nanohoneycombs and carbon nanotubes were demonstrated. Different growth techniques such as pulsed laser deposition, DC/RF sputtering, hot filament physical vapour deposition, evaporative casting and vacuum filtration methods were introduced or applied for synthesizing carbon nanomaterials. The morphology, chemical compositions, bond structures, electronic, mechanical and sensing properties of the obtained samples were investigated. Tilted well-aligned carbon micro- and nano- hybrid rods were fabricated on Si at different substrate temperatures and incident angles of carbon source beam using the hot filament physical vapour deposition technique. The morphologic surfaces and bond structures of the oblique carbon rod-like structures were investigated by scanning electron microscopy, field emission scanning electron microscopy, transmission electron diffraction and Raman scattering spectroscopy. The field emission behaviour of the fabricated samples was also tested. Carbon nanosheets and nanohoneycombs were also synthesized on Si substrates using a hot filament physical vapor deposition technique under methane ambient and vacuum, respectively. The four-point Au electrodes are then sputtered on the surface of the nanostructured carbon films to form prototypical humidity sensors. The sensing properties of prototypical sensors at different temperature, humidity, direct current, and alternative current voltage were characterized. Linear sensing response of sensors to relative humidity ranging from 11% to 95% is observed at room temperature. Experimental data indicate that the carbon nanosheets based sensors exhibit an excellent reversible behavior and long-term stability. It also has higher response than that of the humidity sensor with carbon nanohoneycombs materials. Conducting composite films containing carbon nanotubes (CNTs) were prepared in

Ion evaporation from the surface of a Taylor cone.

PubMed

Higuera, F J

2003-07-01

An analysis is carried out of the electric field-induced evaporation of ions from the surface of a polar liquid that is being electrosprayed in a vacuum. The high-field cone-to-jet transition region of the electrospray, where ion evaporation occurs, is studied taking advantage of its small size and neglecting the inertia of the liquid and the space charge around the liquid. Evaporated ions and charged drops coexist in a range of flow rates, which is investigated numerically. The structure of the cone-to-jet transition comprises: a hydrodynamic region where the nearly equipotential surface of the liquid departs from a Taylor cone and becomes a jet; a slender region where the radius of the jet decreases and the electric field increases while the pressure and the viscous stress balance the electric stress at the surface; the ion evaporation region of high, nearly constant field; and a charged, continuously strained jet that will eventually break into drops. Estimates of the ion and drop contributions to the total, conduction-limited current show that the first of these contributions dominates for small flow rates, while most of the mass is still carried by the drops.

Electron Beam-Induced Deposition for Atom Probe Tomography Specimen Capping Layers.

PubMed

Diercks, David R; Gorman, Brian P; Mulders, Johannes J L

2017-04-01

Six precursors were evaluated for use as in situ electron beam-induced deposition capping layers in the preparation of atom probe tomography specimens with a focus on near-surface features where some of the deposition is retained at the specimen apex. Specimens were prepared by deposition of each precursor onto silicon posts and shaped into sub-70-nm radii needles using a focused ion beam. The utility of the depositions was assessed using several criteria including composition and uniformity, evaporation behavior and evaporation fields, and depth of Ga+ ion penetration. Atom probe analyses through depositions of methyl cyclopentadienyl platinum trimethyl, palladium hexafluoroacetylacetonate, and dimethyl-gold-acetylacetonate [Me2Au(acac)] were all found to result in tip fracture at voltages exceeding 3 kV. Examination of the deposition using Me2Au(acac) plus flowing O2 was inconclusive due to evaporation of surface silicon from below the deposition under all analysis conditions. Dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9] depositions were found to be effective as in situ capping materials for the silicon specimens. Their very different evaporation fields [36 V/nm for Co2(CO)8 and 21 V/nm for Fe2(CO)9] provide options for achieving reasonably close matching of the evaporation field between the capping material and many materials of interest.

Excellent vacuum tribological properties of Pb/PbS film deposited by RF magnetron sputtering and ion sulfurizing.

PubMed

Guozheng, Ma; Binshi, Xu; Haidou, Wang; Shuying, Chen; Zhiguo, Xing

2014-01-08

Soft metal Pb film of 3 μm in thickness was deposited on AISI 440C steel by RF magnetron sputtering, and then some of the Pb film samples were treated by low-temperature ion sulfurizing (LTIS) and formed Pb/PbS composite film. Tribological properties of the Pb and Pb/PbS films were tested contrastively in vacuum and air condition using a self-developed tribometer (model of MSTS-1). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to analyze the microstructure and chemical construction of the films and their worn surfaces. The results show that a mass of Pb was changed to PbS during the process of LTIS. In air condition, owing to the severe oxidation effect, pure Pb film showed relatively high friction coefficients (0.6), and Pb/PbS composite film also lost its friction-reduction property after sliding for a short time. In a vacuum, the average friction coefficients of Pb film were about 0.1, but the friction coefficient curve fluctuated obviously. And the Pb/PbS composite film exhibited excellent tribological properties in vacuum condition. Its friction coefficients keep stable at a low value of about 0.07 for a long time. If takes the value of friction coefficients exceeding 0.2 continuously as a criterion of lubrication failure, the sliding friction life of Pb/PbS film was as long as 3.2 × 10(5) r, which is 8 times of that of the Pb film. It can be concluded that the Pb/PbS film has excellent vacuum tribological properties and important foreground for applying in space solid lubrication related fields.

[Preparation and transmissivity of ZnS nanocolumn thin films with glancing angle deposition technology].

PubMed

Lu, Li-Fang; Xu, Zheng; Zhang, Fu-Jun; Zhao, Su-Ling; Song, Dan-Dan; Li, Jun-Ming; Wang, Yong-Sheng; Xu, Xu-Rong

2010-02-01

Nanocrystalline ZnS thin films were fabricated by glancing angle deposition (GLAD) technology in an electron beam evaporation system. Deposition was carried out in the custom vacuum chamber at a base pressure 3 x 10(-4) Pa, and the deposition rate was fixed at 0.2 nm x s(-1). ZnS films were deposited on pieces of indium tin oxide (ITO) substrates when the oblique angle of the substrate relative to the incoming molecular flux was set to 0 degrees, 80 degrees and 85 degrees off the substrate normal respectively. X-ray diffraction (XRD) spectra and scanning electron microscope (SEM) images showed that ZnS nanocrystalline films were formed on the substrates at different oblique angle, but the nanocolumn structure was only formed under the situation of alpha = 80 degrees and 85 degrees. The dynamics during the deposition process of the ZnS films at alpha = 0 degrees, 80 degrees and 85 degrees was analyzed. The transmitted spectra of ZnS thin films deposited on ITO substrates showed that the ZnS nanocolumn thin films could enhance the transmissivity in visible range. The ZnS nanocolumn could be used into electroluminescence device, and it would enhance the luminous efficiency of the device.

Effect of substrate and post-deposition annealing on nanostructure and optical properties of CdTe thin films

NASA Astrophysics Data System (ADS)

Hasani, Ebrahim; Raoufi, Davood

2018-04-01

Thermal evaporation is one of the promising methods for depositing CdTe thin films, which can obtain the thin films with the small thickness. In this work, CdTe nanoparticles have deposited on SiO2 substrates such as quartz (crystal) and glass (amorphous) at a temperature (Ts) of 150 °C under a vacuum pressure of 2 × 10‑5 mbar. The thickness of CdTe thin films prepared under vacuum pressure is 100 nm. X-ray diffraction analysis (XRD) results showed the formation of CdTe cubic phase with a strong preferential orientation of (111) crystalline plane on both substrates. The grain size (D) in this orientation obtained about 7.41 and 5.48 nm for quartz and glass respectively. Ultraviolet-visible spectroscopy (UV–vis) measurements indicated the optical band gap about 1.5 and 1.52 eV for CdTe thin films deposited on quartz and glass respectively. Furthermore, to show the effect of annealing temperature on structure and optical properties of CdTe thin films on quartz and glass substrates, the thin films have been annealed at temperatures 50 and 70 °C for one hour. The results of this work indicate that the structure’s parameters and optical properties of CdTe thin films change due to increase in annealing temperature.

Discontinuous contact line motion of evaporating particle-laden droplet on superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Yamada, Yutaka; Horibe, Akihiko

2018-04-01

The three-phase contact line motion on a superhydrophobic surface through particle-laden sessile droplet evaporation was investigated. Sample surfaces with micro- and nanoscale structures were generated by various durations of chemical treatment and Si O2 spherical particles with different sizes were used as additives of test liquid. The contact angle and contact radius profiles were studied, and the discontinuous motion of those profiles on micro- and nanostructured hierarchical surfaces was observed, while it was not observed on a nanostructured superhydrophobic surface. Suspensions with low particle concentration induced a relatively large contact radius jump compared to the high-concentrated condition; in contrast, the previous report showed the opposite trend for flat surfaces. In order to explain this result, a simple explanation was provided—that the stacked particles at the contact line region suppressed to the deformation of the liquid-vapor interface near the contact line. This is confirmed by side-view images of the deposition results because the contact line region after evaporation of the dense suspension showed a large contact angle compared to that of the diluted suspension. In addition, deposition at the contact line region was observed by scanning electron microscopy to discuss the effect of the characteristic length scale of the surface structure and particles on the contact line motion. We believe that these results will help one to understand the deposition phenomenon during particle-laden droplet evaporation on the superhydrophobic surface and its applications such as evaporation-driven materials deposition.

Vacuum arc plasma deposition of thin titanium dioxide films on silicone elastomer as a functional coating for medical applications.

PubMed

Boudot, Cécile; Kühn, Marvin; Kühn-Kauffeldt, Marina; Schein, Jochen

2017-05-01

Silicone elastomer is a promising material for medical applications and is widely used for implants with blood and tissue contact. However, its strong hydrophobicity limits adhesion of tissue cells to silicone surfaces, which can impair the healing process. To improve the biological properties of silicone, a triggerless pulsed vacuum cathodic arc plasma deposition technique was applied to deposit titanium dioxide (TiO 2 ) films onto the surface. Scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and contact angle measurements were used for coating characterization. Deposited films were about 150nm thick and exhibited good adhesion to the underlying silicone substrate. Surface wettability and roughness both increased after deposition of the TiO 2 layer. In addition, cell-biological investigations demonstrated that the in-vitro cytocompatibility of TiO 2 -coated samples was greatly improved without impacting silicone's nontoxicity. For validation of use in medical devices, further investigations were conducted and demonstrated stability of surface properties in an aqueous environment for a period of 68days and the coating's resistance to several sterilization methods. Copyright © 2016 Elsevier B.V. All rights reserved.

Vacuum Plasma Spraying Replaces Electrodeposition

NASA Technical Reports Server (NTRS)

Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

1992-01-01

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Complex technology of vacuum-arc processing of structural material surface

NASA Astrophysics Data System (ADS)

Arustamov, V. N.; Ashurov, Kh. B.; Kadyrov, Kh. Kh.; Khudoikulov, I. Kh.

2015-08-01

The development of environmentally friendly and energy-resource-saving technologies based on vacuum arc discharge is a topical problem in science and engineering. In view of their unique properties, cathode spots of a vacuum arc induce cleaning of the surface of an article (cathode) from various contaminations and pulsed thermal action on the surface layers. These processes occur in complex with vacuum-arc deposition of coatings in the same technological cycle, which makes it possible to considerably increase the efficiency of methods for changing physical, mechanical, and chemical properties of the surface of steel articles, which considerably increase their service life. Analysis of the formation of the temperature regime of the surface during vacuum arc action and of the parameters of the deposited coating will make it possible to optimize the regimes of complex treatment of the surfaces of articles and is of considerable theoretical and practical importance.

Numerical Study on Natural Vacuum Solar Desalination System with Varying Heat Source Temperature

NASA Astrophysics Data System (ADS)

Ambarita, H.

2017-03-01

A natural vacuum desalination unit with varying low grade heat source temperature is investigated numerically. The objective is to explore the effects of the variable temperature of the low grade heat source on performances and characteristics of the desalination unit. The specifications of the desalination unit are naturally vacuumed with surface area of seawater in evaporator and heating coil are 0.2 m2 and 0.188 m2, respectively. Temperature of the heating coil is simulated based on the solar radiation in the Medan city. A program to solve the governing equations in forward time step marching technique is developed. Temperature of the evaporator, fresh water production rate, and thermal efficiency of the desalination unit are analysed. Simulation is performed for 9 hours, it starts from 8.00 and finishes at 17.00 of local time. The results show that, the desalination unit with operation time of 9 hours can produce 5.705 L of freshwater and thermal efficiency is 81.8 %. This reveals that varying temperature of the heat source of natural vacuum desalination unit shows better performance in comparison with constant temperature of the heat source.

Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

PubMed

Libralato, G; Ghirardini, A Volpi; Avezzù, F

2008-05-30

Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

Nanocomposite TiN films with embedded MoS2 inorganic fullerenes produced by combining supersonic cluster beam deposition with cathodic arc reactive evaporation

NASA Astrophysics Data System (ADS)

Piazzoni, C.; Blomqvist, M.; Podestà, A.; Bardizza, G.; Bonati, M.; Piseri, P.; Milani, P.; Davies, C.; Hatto, P.; Ducati, C.; Sedláčková, K.; Radnóczi, G.

2008-01-01

We report the production and characterization of nanocomposite thin films consisting of a titanium nitride matrix with embedded molybdenum disulphide fullerene-like nanoparticles. This was achieved by combining a cluster source generating a pulsed supersonic beam of MoS2 clusters with an industrial cathodic arc reactive evaporation apparatus used for TiN deposition. Cluster-assembled films show the presence of MoS2 nanocages and nanostructures and the survival of such structures dispersed in the TiN matrix in the co-deposited samples. Nanotribological characterization by atomic force microscopy shows that the presence of MoS2 nanoparticles even in very low concentration modifies the behaviour of the TiN matrix.

Investigations on Structural, Optical and X-Radiation Responsive Properties of a-Se Thin Films Fabricated by Thermal Evaporation Method at Low Vacuum Degree.

PubMed

Li, Jitao; Zhu, Xinghua; Yang, Dingyu; Gu, Peng; Wu, Haihua

2018-03-02

Amorphous selenium (a-Se) thin films with a thickness of 1200 nm were successfully fabricated by thermal evaporation at a low vacuum degree of 10 -2 Pa. The structural properties involving phase and morphology showed that a-Se thin films could be resistant to 60 °C in air. Also, a transformation to polycrystalline Selenium (p-Se) was shown as the annealing temperature rose to 62 °C and 65 °C, with obvious changes in color and surface morphology. Moreover, as the a-Se transformed to p-Se, the samples' transmittance decreased significantly, and the band gap declined dramatically from 2.15 eV to 1.92 eV. Finally, the X-radiation response of a-Se was investigated as an important property, revealing there is a remarkable response speed of photogeneration current both X-ray on and X-ray off, with a requirement of only a very small electrical field.

Size effects and electron microscopy of thin metal films. M.S. Thesis

NASA Technical Reports Server (NTRS)

Hernandez, J. D.

1978-01-01

All films were deposited by resistive heated evaporation in an oil diffusion pumped vacuum system (ultimate approx. equal to 0.0000001 torr). The growth from nuclei to a continuous film is highly dependent on the deposition parameters, evaporation rate as well as substrate material and substrate temperature. The growth stages of a film and the dependence of grain size on various deposition and annealing parameters are shown. Resistivity measurements were taken on thin films to observe size effects.

Evaporation-induced flow in an inviscid liquid line at any contact angle

NASA Astrophysics Data System (ADS)

Petsi, A. J.; Burganos, V. N.

2006-04-01

The problem of potential flow inside an evaporating liquid line, shaped as an infinitely long cylindrical segment lying on a flat surface, is considered and an analytical solution is obtained for any contact angle in (0,π) . In this way, microflow details inside linear liquid bodies evaporating on hydrophilic, hydrophobic, and strongly hydrophobic substrates can now be obtained. The mathematical formulation employs the velocity potential and stream function formulations in bipolar coordinates and the solution is obtained using the technique of Fourier transform. Both pinned and depinned contact lines are considered. The solution is applicable to any evaporation mechanism but for illustration purposes numerical results are presented here for the particular case of kinetically controlled evaporation. For hydrophilic substrates, the flow inside the evaporating liquid line is directed towards the edges for pinned contact lines, thus, promoting a coffee stain effect. The opposite flow direction is observed for depinned contact lines. However, for strongly hydrophobic substrates, flow is directed outwards for both pinned and depinned contact lines, but owing to its low magnitude compared to that on hydrophilic substrates, a craterlike colloidal deposit should be expected rather than a ringlike deposit, in agreement with experimental observations.

Ion assisted deposition of SiO2 film from silicon

NASA Astrophysics Data System (ADS)

Pham, Tuan. H.; Dang, Cu. X.

2005-09-01

Silicon dioxide, SiO2, is one of the preferred low index materials for optical thin film technology. It is often deposited by electron beam evaporation source with less porosity and scattering, relatively durable and can have a good laser damage threshold. Beside these advantages the deposition of critical optical thin film stacks with silicon dioxide from an E-gun was severely limited by the stability of the evaporation pattern or angular distribution of the material. The even surface of SiO2 granules in crucible will tend to develop into groove and become deeper with the evaporation process. As the results, angular distribution of the evaporation vapor changes in non-predicted manner. This report presents our experiments to apply Ion Assisted Deposition process to evaporate silicon in a molten liquid form. By choosing appropriate process parameters we can get SiO2 film with good and stable property.

Accurate evaporation rates of pure and doped water clusters in vacuum: A statistico-dynamical approach

NASA Astrophysics Data System (ADS)

Calvo, F.; Douady, J.; Spiegelman, F.

2010-01-01

Unimolecular evaporation of selected pure (H2O)n and heterogeneous (H2O)n-1X+ water clusters containing a single hydronium or ammonium impurity is investigated in the framework of phase space theory (PST) in its orbiting transition state version. Using the many-body polarizable Kozack-Jordan potential and its extensions for X+=H3O+ and NH4+, the thermal evaporation of clusters containing 21 and 50 molecules is simulated at several total energies. Numerous molecular dynamics (MD) trajectories at high internal energies provide estimates of the decay rate constant, as well as the kinetic energy and angular momentum released upon dissociation. Additional Monte Carlo simulations are carried out to determine the anharmonic densities of vibrational states, which combined with suitable forms for the rotational densities of states provide expressions for the energy-resolved differential rates. Successful comparison between the MD results and the independent predictions of PST for the distributions of kinetic energy and angular momentum released shows that the latter statistical approach is quantitative. Using MD data as a reference, the absolute evaporation rates are calculated from PST over broad energy and temperature ranges. Based on these results, the presence of an ionic impurity is generally found to decrease the rate, however the effect is much more significant in the 21-molecule clusters. Our calculations also suggest that due to backbendings in the microcanonical densities of states the variations of the evaporation rates may not be strictly increasing with energy or temperature.

Treatment of evaporator condensates by pervaporation

DOEpatents

Blume, Ingo; Baker, Richard W.

1990-01-01

A pervaporation process for separating organic contaminants from evaporator condensate streams is disclosed. The process employs a permselective membrane that is selectively permeable to an organic component of the condensate. The process involves contacting the feed side of the membrane with a liquid condensate stream, and withdrawing from the permeate side a vapor enriched in the organic component. The driving force for the process is the in vapor pressure across the membrane. This difference may be provided for instance by maintaining a vacuum on the permeate side, or by condensing the permeate. The process offers a simple, economic alternative to other separation techniques.

Plasmonic properties of gold nanoparticles covered by silicon suboxide thin film

NASA Astrophysics Data System (ADS)

Baranov, Evgeniy; Zamchiy, Alexandr; Safonov, Aleksey; Starinskiy, Sergey; Khmel, Sergey

2017-10-01

The optical properties of nanocomposite material consisting of gold nanoparticles without/with silicon suboxide thin film were obtained. The gold film was deposited by thermal vacuum evaporation and then it was annealed in a vacuum chamber to form gold nanoparticles. The silicon suboxide thin films were deposited by the gas-jet electron beam plasma chemical vapor deposition method. The intensity of the localized surface plasmon resonance increased and the plasmon maximum peak shifted from 520 nm to 537 nm.

Formation Dynamics of CH3NH3PbI3 Perovskite Following Two-Step Layer Deposition.

PubMed

Patel, Jay B; Milot, Rebecca L; Wright, Adam D; Herz, Laura M; Johnston, Michael B

2016-01-07

Hybrid metal-halide perovskites have emerged as a leading class of semiconductors for optoelectronic devices because of their desirable material properties and versatile fabrication methods. However, little is known about the chemical transformations that occur in the initial stages of perovskite crystal formation. Here we follow the real-time formation dynamics of MAPbI3 from a bilayer of lead iodide (PbI2) and methylammonium iodide (MAI) deposited through a two-step thermal evaporation process. By lowering the substrate temperature during deposition, we are able to initially inhibit intermixing of the two layers. We subsequently use infrared and visible light transmission, X-ray diffraction, and photoluminescence lifetime measurements to reveal the room-temperature transformations that occur in vacuum and ambient air, as MAI diffuses into the PbI2 lattice to form MAPbI3. In vacuum, the transformation to MAPbI3 is incomplete as unreacted MAI is retained in the film. However, exposure to moist air allows for conversion of the unreacted MAI to MAPbI3, demonstrating that moisture is essential in making MAI more mobile and thus aiding perovskite crystallization. These dynamic processes are reflected in the observed charge-carrier lifetimes, which strongly fluctuate during periods of large ion migration but steadily increase with improving crystallinity.

14. VIEW OF VACUUM COATING CHAMBER. THE SYSTEM USED TITANIUM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. VIEW OF VACUUM COATING CHAMBER. THE SYSTEM USED TITANIUM VAPORS TO DEPOSIT TITANIUM COATING ONTO URANIUM PARTS UNDER A VACUUM. (1/11/83) - Rocky Flats Plant, Non-Nuclear Production Facility, South of Cottonwood Avenue, west of Seventh Avenue & east of Building 460, Golden, Jefferson County, CO

Vacuum vapor deposition gun assembly

DOEpatents

Zeren, Joseph D.

1985-01-01

A vapor deposition gun assembly includes a hollow body having a cylindrical outer surface and an end plate for holding an adjustable heat sink, a hot hollow cathode gun, two magnets for steering the plasma from the gun into a crucible on the heat sink, and a shutter for selectively covering and uncovering the crucible.

Towards bio-silicon interfaces: Formation of an ultra-thin self-hydrated artificial membrane composed of dipalmitoylphosphatidylcholine (DPPC) and chitosan deposited in high vacuum from the gas-phase

NASA Astrophysics Data System (ADS)

Retamal, María J.; Cisternas, Marcelo A.; Gutierrez-Maldonado, Sebastian E.; Perez-Acle, Tomas; Seifert, Birger; Busch, Mark; Huber, Patrick; Volkmann, Ulrich G.

2014-09-01

The recent combination of nanoscale developments with biological molecules for biotechnological research has opened a wide field related to the area of biosensors. In the last years, device manufacturing for medical applications adapted the so-called bottom-up approach, from nanostructures to larger devices. Preparation and characterization of artificial biological membranes is a necessary step for the formation of nano-devices or sensors. In this paper, we describe the formation and characterization of a phospholipid bilayer (dipalmitoylphosphatidylcholine, DPPC) on a mattress of a polysaccharide (Chitosan) that keeps the membrane hydrated. The deposition of Chitosan (˜25 Å) and DPPC (˜60 Å) was performed from the gas phase in high vacuum onto a substrate of Si(100) covered with its native oxide layer. The layer thickness was controlled in situ using Very High Resolution Ellipsometry (VHRE). Raman spectroscopy studies show that neither Chitosan nor DPPC molecules decompose during evaporation. With VHRE and Atomic Force Microscopy we have been able to detect phase transitions in the membrane. The presence of the Chitosan interlayer as a water reservoir is essential for both DPPC bilayer formation and stability, favoring the appearance of phase transitions. Our experiments show that the proposed sample preparation from the gas phase is reproducible and provides a natural environment for the DPPC bilayer. In future work, different Chitosan thicknesses should be studied to achieve a complete and homogeneous interlayer.

Crystalline desiccation patterns and film break up from evaporating drops on hydrophobic oxide surfaces

NASA Astrophysics Data System (ADS)

McBride, Samantha; Dash, Susmita; Khan, Sami; Varanasi, Kripa

2017-11-01

Solute-laden sessile drops evaporating on a substrate will often force crystallization of the solute at the triple phase contact line between the drop, substrate, and air in an effect similar to the ``coffee-ring'' deposition of particles from a particle-laden drop. We report new observations of ring-shaped desiccation patterns of gypsum crystals on hydrophobic oxide substrates; ceria, erbia, and silica. These surfaces have similar contact angles ( 105 degrees), and evaporation of sessile drops proceeds at the same rate and without contact angle hysteresis on all three substrates. However, despite the apparent similarity, the patterns of crystal deposits exhibit large differences across the substrates. The supersaturation and elapsed time at the onset of crystallization also varied across substrates, despite overall evaporation rates being identical. The differences in patterns can be explained in light of the position and morphology of the crystals just prior to completion of evaporation when the sessile drop has transitioned to a thin film spread over the deposit area. Break-up of this film occurs very differently on the different surfaces, and is simultaneously influenced by existing crystals while also influencing final crystalline patterns. This work was supported by the NSF GRFP.

OPTIMAL ELECTRON ENERGIES FOR DRIVING CHROMOSPHERIC EVAPORATION IN SOLAR FLARES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reep, J. W.; Bradshaw, S. J.; Alexander, D., E-mail: jr665@cam.ac.uk, E-mail: stephen.bradshaw@rice.edu, E-mail: dalex@rice.edu

2015-08-01

In the standard model of solar flares, energy deposition by a beam of electrons drives strong chromospheric evaporation leading to a significantly denser corona and much brighter emission across the spectrum. Chromospheric evaporation was examined in great detail by Fisher et al., who described a distinction between two different regimes, termed explosive and gentle evaporation. In this work, we examine the importance of electron energy and stopping depths on the two regimes and on the atmospheric response. We find that with explosive evaporation, the atmospheric response does not depend strongly on electron energy. In the case of gentle evaporation, lowermore » energy electrons are significantly more efficient at heating the atmosphere and driving up-flows sooner than higher energy electrons. We also find that the threshold between explosive and gentle evaporation is not fixed at a given beam energy flux, but also depends strongly on the electron energy and duration of heating. Further, at low electron energies, a much weaker beam flux is required to drive explosive evaporation.« less

Effect of vacuum annealing and substrate temperature on structural and optical properties of ZnIn2Se4 thin films

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Attia, A. A.; Salem, G. F.; Ali, H. A. M.; Ismail, M. I.

2013-09-01

Zinc indium selenide (ZnIn2Se4) thin films were prepared by the thermal evaporation technique with high deposition rate. The effect of thermal annealing in vacuum on the crystallinity of the as-deposited films was studied at different temperatures (523, 573 and 623 K). The effect of substrate temperature (623 K) for different thickness values (173, 250, 335 and 346 nm) on the optical parameters of ZnIn2Se4 was also studied. The structural studies showed nanocrystalline nature of the room temperature (300 K) deposited films with crystallite size of about a few nanometers. The crystallite size increased up to 31 nm with increasing the annealing temperature in vacuum. From the reflection and transmission data, the refractive index n and the extinction coefficient k were estimated for ZnIn2Se4 thin films and they were found to be independent of film thickness. Analysis of the absorption coefficient data of the as-deposited films revealed the existence of allowed direct and indirect transitions with optical energy gaps of 2.21 eV and 1.71 eV, respectively. These values decreased with increasing annealing temperature. At substrate temperature of 623 K, the direct band gap increased to 2.41 eV whereas the value of indirect band gap remained nearly unchanged. The dispersion analysis showed that the values of the oscillator energy Eo, dispersion energy Ed, dielectric constant at infinite frequency ε∞, and lattice dielectric constant εL were changed appreciably under the effect of annealing and substrate temperature. The covalent nature of structure was studied as a function of the annealing and substrate temperature using an empirical relation for the dispersion energy Ed. Generalized Miller's rule and linear refractive index were used to estimate the nonlinear susceptibility and nonlinear refractive index of the thin films.

Structural and evaporative evolutions in desiccating sessile drops of blood

NASA Astrophysics Data System (ADS)

Sobac, B.; Brutin, D.

2011-07-01

We report an experimental investigation of the drying of a deposited drop of whole blood. Flow motion, adhesion, gelation, and fracturation all occur during the evaporation of this complex matter, leading to a final typical pattern. Two distinct regimes of evaporation are highlighted: the first is driven by convection, diffusion, and gelation in a liquid phase, whereas the second, with a much slower rate of evaporation, is characterized by the mass transport of the liquid left over in the gellified biocomponent matter. A diffusion model of the drying process allows a prediction of the transition between these two regimes of evaporation. Moreover, the formation of cracks and other events occurring during the drying are examined and shown to be driven by critical solid mass concentrations.

Experimental and Numerical Study of the Evaporation of Water at Low Pressures.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-05-09

Although evaporation is considered to be a surface phenomenon, the rate of molecular transport across a liquid-vapor boundary is strongly dependent on the coupled fluid dynamics and heat transfer in the bulk fluids. Recent experimental thermocouple measurements of the temperature field near the interface of evaporating water into its vapor have begun to show the role of heat transfer in evaporation. However, the role of fluid dynamics has not been explored sufficiently. Here, we have developed a mathematical model to describe the coupling of the heat, mass, and momentum transfer in the fluids with the transport phenomena at the interface. The model was used to understand the experimentally obtained velocity field in the liquid and temperature profiles in the liquid and vapor, in evaporation from a concave meniscus for various vacuum pressures. By using the model, we have shown that an opposing buoyancy flow suppressed the thermocapillary flow in the liquid during evaporation at low pressures in our experiments. As such, in the absence of thermocapillary convection, the evaporation is controlled by heat transfer to the interface, and the predicted behavior of the system is independent of choosing between the existing theoretical expressions for evaporation flux. Furthermore, we investigated the temperature discontinuity at the interface and confirmed that the discontinuity strongly depends on the heat flux from the vapor side, which depends on the geometrical shape of the interface.

Renormalized Stress-Energy Tensor of an Evaporating Spinning Black Hole.

PubMed

Levi, Adam; Eilon, Ehud; Ori, Amos; van de Meent, Maarten

2017-04-07

We provide the first calculation of the renormalized stress-energy tensor (RSET) of a quantum field in Kerr spacetime (describing a stationary spinning black hole). More specifically, we employ a recently developed mode-sum regularization method to compute the RSET of a minimally coupled massless scalar field in the Unruh vacuum state, the quantum state corresponding to an evaporating black hole. The computation is done here for the case a=0.7M, using two different variants of the method: t splitting and φ splitting, yielding good agreement between the two (in the domain where both are applicable). We briefly discuss possible implications of the results for computing semiclassical corrections to certain quantities, and also for simulating dynamical evaporation of a spinning black hole.

Note: A microfluidic freezer based on evaporative cooling of atomized aqueous microdroplets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Jin; Kim, Dohyun, E-mail: dohyun.kim@mju.ac.kr; Chung, Minsub

2015-01-15

We report for the first time water-based evaporative cooling integrated into a microfluidic chip for temperature control and freezing of biological solution. We opt for water as a nontoxic, effective refrigerant. Aqueous solutions are atomized in our device and evaporation of microdroplets under vacuum removes heat effectively. We achieve rapid cooling (−5.1 °C/s) and a low freezing temperature (−14.1 °C). Using this approach, we demonstrate freezing of deionized water and protein solution. Our simple, yet effective cooling device may improve many microfluidic applications currently relying on external power-hungry instruments for cooling and freezing.

Construction of vacuum system for Tristan accumulation ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishimaru, H.; Horikoshi, G.; Kobayashi, M.

1983-08-01

An all aluminum-alloy vacuum system for the TRISTAN accumulation ring is now under construction. Aluminum and aluminum alloys are preferred materials for ultrahigh vacuum systems of large electron storage rings because of their good thermal conductivity, extremely low outgassing rate, and low residual radioactivity. Vacuum beam chambers for the dipole and quadrupole magnets are extruded using porthole dies. The aluminum alloy 6063-T6 provides superior performance in extrusion. For ultrahigh vacuum performance, a special extrusion technique is applied which, along with the outgassing procedure used, is described in detail. Aluminum alloy 3004 seamless elliptical bellows are inserted between the dipole andmore » quadrupole magnet chambers. These bellows are produced by the hydraulic forming of a seamless tube. The seamless bellows and the beam chambers are joined by fully automatic welding. The ceramic chambers for the kicker magnets, the fast bump magnets, and the slow beam intensity monitor are inserted in the aluminum alloy beam chambers. The ceramic chamber (98% alumina) and elliptical bellows are brazed with brazing sheets (4003-3003-4003) in a vacuum furnace. The brazing technique is described. The inner surface of the ceramic chamber is coated with a TiMo alloy by vacuum evaporation to permit a smooth flow of the RF wall current. Other suitable aluminum alloy components, including fittings, feedthroughs, gauges, optical windows, sputter ion pumps, turbomolecular pumps, and valves have been developed; their fabrication is described.« less

Evaporation of sessile drops containing colloidal rods: coffee-ring and order-disorder transition.

PubMed

Dugyala, Venkateshwar Rao; Basavaraj, Madivala G

2015-03-05

Liquid drops containing insoluble solutes when dried on solid substrates leave distinct ring-like deposits at the periphery or along the three-phase contact line-a phenomena popularly known as the coffee-ring or the coffee stain effect. The formation of such rings as well as their suppression is shown to have applications in particle separation and disease diagnostics. We present an experimental study of the evaporation of sessile drops containing silica rods to elucidate the structural arrangement of particles in the ring, an effect of the addition of surfactant and salt. To this end, the evaporation of aqueous sessile drops containing model rod-like silica particles of aspect ratio ranging from ∼4 to 15 on a glass slide is studied. We first show that when the conditions such as (1) solvent evaporation, (2) nonzero contact angle, (3) contact line pinning, (4) no surface tension gradient driven flow, and (5) repulsive particle-particle/particle-substrate interactions, that are necessary for the formation of the coffee-ring are met, the suspension drops containing silica rods upon evaporation leave a ring-like deposit. A closer examination of the ring deposits reveals that several layers of silica rods close to the edge of the drop are ordered such that the major axis of the rods are oriented parallel to the contact line. After the first few layers of ordered arrangement of particles, a random arrangement of particles in the drop interior is observed indicating an order-disorder transition in the ring. We monitor the evolution of the ring width and particle velocity during evaporation to elucidate the mechanism of the order-disorder transition. Moreover, when the evaporation rate is lowered, the ordering of silica rods is observed to extend over large areas. We demonstrate that the nature of the deposit can be tuned by the addition of a small quantity of surfactant or salt.

Direct synthesis of Cu{sub 2}O-RGO nanocomposite on Cu foil by thermal evaporation method and its field emission study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bansode, Sanjeewani; Khare, Ruchita; Harpale, Kashmira

2015-06-24

In this work, a facile one step thermal evaporation method for deposition of Cu{sub 2}O nanoparticles on RGO sheets to form Cu{sub 2}O-RGO nanocomposite is discussed. To the best of our knowledge, this is the first report on Cu{sub 2}O-RGO nanocomposite, directly grown on Cu foil by a simple thermal evaporation route. The as –prepared nanocomposite exhibits well dispersed Cu{sub 2}O nanoparticles distributed all over the graphene sheet. Field emission properties of the nanocomposite were investigated at a base pressure of 1*10{sup −8} torr. The turn on field, required to draw emission current density of 0.1µA/cm2, was found to bemore » 3.8V/µm with a maximum emission current density of 80 µA/cm2 at an applied field of 6.8 V/µm. Moreover, the nanocomposite shows fairly good emission stability without significant degradation of emission current. The FE results seem to be encouraging, indicative of potential candidature of the Cu{sub 2}O-RGO nanocomposite emitter as an electron source for practical applications in vacuum nanoelectronic devices.« less

Electrostatic measurement of plasma plume characteristics in pulsed laser evaporated carbon

NASA Astrophysics Data System (ADS)

Mayo, R. M.; Newman, J. W.; Sharma, A.; Yamagata, Y.; Narayan, J.

1999-09-01

A triple Langmuir probe measurement has been implemented to investigate plasma plume character in low fluence (˜3.0 J/cm2) pulsed laser evaporation (PLE) discharges and has been found to be an extremely valuable tool. Absolute plasma plume density estimates are found to reside in the range 1.0×1013-2.0×1014cm-3 for vacuum pulses. A simple heavy particle streaming model for vacuum pulses allows estimates of the plume ionization fraction of ˜10%. This is consistent with typical deposition inventory suggesting that high kinetic energy ions may play an important role in diamond-like carbon (DLC) film deposition. Electron temperature inferred from the electrostatic probe is found to consistently reside in the range 0.5-3.0 eV, and appears to be uninfluenced by operating conditions and large variations in Ar and N2 fill gas pressure. Consistent with strong plume ion and neutral particle coupling to the background fill, constancy of Te suggests expulsion of background gas by the energetic plume. The leading edge ion plume speed is measured via temporal displacement of spatially separated probe signals on consecutive PLE pulses. Flow speeds as high as 5.0×104m/s are observed, corresponding to ˜156 eV in C+. The ion flow speed is found to be a strongly decreasing function of fill pressure from an average high of ˜126 eV in vacuum to ˜0.24 eV at 600 mTorr N2. Raman scattering spectroscopy indicates DLC film quality also degrades with fill pressure suggesting the importance of high ion kinetic energy in producing good quality films, consistent with earlier work demonstrating the importance of energetic particles. Optical emission indicates an increase in C2 molecular light intensity with fill gas pressure implying a reduced, if any, role of these species in DLC production. Ion current signal anomalies are often seen during high pressure pulses. It is suggested that this may indicate the formation of high mass carbon clusters during plume evolution in the presence of

Experimental investigation on the energy deposition and morphology of the electrical explosion of copper wire in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zongqian; Shi, Yuanjie; Wang, Kun

2016-03-15

This paper presents the experimental results of the electrical explosion of copper wires in vacuum using negative nanosecond-pulsed current with magnitude of 1–2 kA. The 20 μm-diameter copper wires with different lengths are exploded with three different current rates. A laser probe is applied to construct the shadowgraphy and interferometry diagnostics to investigate the distribution and morphology of the exploding product. The interference phase shift is reconstructed from the interferogram, by which the atomic density distribution is calculated. Experimental results show that there exist two voltage breakdown modes depending on the amount of the specific energy deposition. For the strong-shunting mode, shuntingmore » breakdown occurs, leading to the short-circuit-like current waveform. For the weak-shunting mode with less specific energy deposition, the plasma generated during the voltage breakdown is not enough to form a conductive plasma channel, resulting in overdamped declining current waveform. The influence of the wire length and current rate on the characteristics of the exploding wires is also analyzed.« less

A lithium deposition system for tokamak devices*

NASA Astrophysics Data System (ADS)

Graziul, Christopher; Majeski, Richard; Kaita, Robert; Hoffman, Daniel; Timberlake, John; Card, David

2002-11-01

The production of a lithium deposition system using commercially available components is discussed. This system is intended to provide a fresh lithium wall coating between discharges in a tokamak. For this purpose, a film 100-200 Å thick is sufficient to ensure that the plasma interacts solely with the lithium. A test system consisting of a lithium evaporator and a deposition monitor has been designed and constructed to investigate deposition rates and coverage. A Thermionics 3kW e-gun is used to rapidly evaporate small amounts of solid lithium. An Inficon XTM/2 quartz deposition monitor then measures deposition rate at varying distances, positions and angles relative to the e-gun crucible. Initial results from the test system will be presented. *Supported by US DOE contract #DE-AC02-76CH-03073

Thermal Gradient During Vacuum-Deposition Dramatically Enhances Charge Transport in Organic Semiconductors: Toward High-Performance N-Type Organic Field-Effect Transistors.

PubMed

Kim, Joo-Hyun; Han, Singu; Jeong, Heejeong; Jang, Hayeong; Baek, Seolhee; Hu, Junbeom; Lee, Myungkyun; Choi, Byungwoo; Lee, Hwa Sung

2017-03-22

A thermal gradient distribution was applied to a substrate during the growth of a vacuum-deposited n-type organic semiconductor (OSC) film prepared from N,N'-bis(2-ethylhexyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboxyimide) (PDI-CN2), and the electrical performances of the films deployed in organic field-effect transistors (OFETs) were characterized. The temperature gradient at the surface was controlled by tilting the substrate, which varied the temperature one-dimensionally between the heated bottom substrate and the cooled upper substrate. The vacuum-deposited OSC molecules diffused and rearranged on the surface according to the substrate temperature gradient, producing directional crystalline and grain structures in the PDI-CN2 film. The morphological and crystalline structures of the PDI-CN2 thin films grown under a vertical temperature gradient were dramatically enhanced, comparing with the structures obtained from either uniformly heated films or films prepared under a horizontally applied temperature gradient. The field effect mobilities of the PDI-CN2-FETs prepared using the vertically applied temperature gradient were as high as 0.59 cm 2 V -1 s -1 , more than a factor of 2 higher than the mobility of 0.25 cm 2 V -1 s -1 submitted to conventional thermal annealing and the mobility of 0.29 cm 2 V -1 s -1 from the horizontally applied temperature gradient.

Sulfur in vacuum - Sublimation effects on frozen melts, and applications to Io's surface and torus

NASA Technical Reports Server (NTRS)

Nash, Douglas B.

1987-01-01

Vacuum sublimation effects on solid sulfur yield a form of the element that is white at room temperature, is fluffy in texture, and forms on frozen sulfur in vacuum through differential evaporation of molecular species in the solid. This vacuum sulfur should exist in large quantity on Io, if the solid free sulfur there has solidified from a melt; a sulfur volcanism model for Io is accordingly developed on this basis which implies that the color and spectra of different sulfur regions of Io could indicate their relative crystallization ages and cooling histories. The flux of sublimating hotspot sulfur appears consistent with estimated turnover rates of the Io surface.

Light-Directed Particle Patterning by Evaporative Optical Marangoni Assembly.

PubMed

Varanakkottu, Subramanyan Namboodiri; Anyfantakis, Manos; Morel, Mathieu; Rudiuk, Sergii; Baigl, Damien

2016-01-13

Controlled particle deposition on surfaces is crucial for both exploiting collective properties of particles and their integration into devices. Most available methods depend on intrinsic properties of either the substrate or the particles to be deposited making them difficult to apply to complex, naturally occurring or industrial formulations. Here we describe a new strategy to pattern particles from an evaporating drop, regardless of inherent particle characteristics and suspension composition. We use light to generate Marangoni surface stresses resulting in flow patterns that accumulate particles at predefined positions. Using projected images, we generate a broad variety of complex patterns, including multiple spots, lines and letters. Strikingly, this method, which we call evaporative optical Marangoni assembly (eOMA), allows us to pattern particles regardless of their size or surface properties, in model suspensions as well as in complex, real-world formulations such as commercial coffee.

Microstructural, nanomechanical, and microtribological properties of Pb thin films prepared by pulsed laser deposition and thermal evaporation techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broitman, Esteban, E-mail: esbro@ifm.liu.se; Flores-Ruiz, Francisco J.; Di Giulio, Massimo

2016-03-15

In this work, the authors compare the morphological, structural, nanomechanical, and microtribological properties of Pb films deposited by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques onto Si (111) substrates. Films were investigated by scanning electron microscopy, surface probe microscopy, and x-ray diffraction in θ-2θ geometry to determine their morphology, root-mean-square (RMS) roughness, and microstructure, respectively. TE films showed a percolated morphology with densely packed fibrous grains while PLD films had a granular morphology with a columnar and tightly packed structure in accordance with the zone growth model of Thornton. Moreover, PLD films presented a more polycrystalline structure withmore » respect to TE films, with RMS roughness of 14 and 10 nm, respectively. Hardness and elastic modulus vary from 2.1 to 0.8 GPa and from 14 to 10 GPa for PLD and TE films, respectively. A reciprocal friction test has shown that PLD films have lower friction coefficient and wear rate than TE films. Our study has demonstrated for first time that, at the microscale, Pb films do not show the same simple lubricious properties measured at the macroscale.« less

Enhancement of the optical and electrical properties of ITO thin films deposited by electron beam evaporation technique

NASA Astrophysics Data System (ADS)

Ali, H. M.; Mohamed, H. A.; Mohamed, S. H.

2005-08-01

Indium tin oxide (ITO) is widely utilized in numerous industrial applications due to its unique combined properties of transparency to visible light and electrical conductivity. ITO films were deposited on glass substrates by an electron beam evaporation technique at room temperature from bulk samples, with different thicknesses. The film with 1500 Å thick was selected to perform annealing in the temperature range of 200 400 °C and annealing for varying times from 15 to 120 min at 400 °C. The X-ray diffraction of the films was analyzed in order to investigate its dependence on thickness, and annealing. Electrical and optical measurements were also carried out. Transmittance, optical energy gap, refractive index, carrier concentration, thermal emissivity and resistivity were investigated. It was found that the as-deposited films with different thicknesses were highly absorbing and have relatively poor electrical properties. The films become opaque with increasing the film thickness. After thermal annealing, the resistance decreases and a simultaneous variation in the optical transmission occurs. A transmittance value of 85.5% in the IR region and 82% in the visible region of the spectrum and a resistivity of 2.8 × 10-4 Ω Cm were obtained at annealing temperature of 400 °C for 120 min.

Example of a Fluid-Phase Change Examined with MD Simulation: Evaporative Cooling of a Nanoscale Droplet.

PubMed

Ao, Takashi; Matsumoto, Mitsuhiro

2017-10-24

We carried out a series of molecular dynamics simulations in order to examine the evaporative cooling of a nanoscale droplet of a Lennard-Jones liquid. After thermally equilibrating a droplet at a temperature T ini /T t ≃ 1.2 (T t is the triple-point temperature), we started the evaporation into vacuum by removing vaporized particles and monitoring the change in droplet size and the temperature inside. As free evaporation proceeds, the droplet reaches a deep supercooled liquid state of T/T t ≃ 0.7. The temperature was found to be uniform in spite of the fast evaporative cooling on the surface. The time evolution of the evaporating droplet properties was satisfactorily explained with a simple one-dimensional phase-change model. After a sufficiently long run, the supercooled droplet was crystallized into a polycrystalline fcc structure. The crystallization is a stochastic nucleation process. The time and the temperature of inception were evaluated over 42 samples, which indicate the existence of a stability limit.

State-of-the-art of recycling e-wastes by vacuum metallurgy separation.

PubMed

Zhan, Lu; Xu, Zhenming

2014-12-16

In recent era, more and more electric and electronic equipment wastes (e-wastes) are generated that contain both toxic and valuable materials in them. Most studies focus on the extraction of valuable metals like Au, Ag from e-wastes. However, the recycling of metals such as Pb, Cd, Zn, and organics has not attracted enough attentions. Vacuum metallurgy separation (VMS) processes can reduce pollution significantly using vacuum technique. It can effectively recycle heavy metals and organics from e-wastes in an environmentally friendly way, which is beneficial for both preventing the heavy metal contaminations and the sustainable development of resources. VMS can be classified into several methods, such as vacuum evaporation, vacuum carbon reduction and vacuum pyrolysis. This paper respectively reviews the state-of-art of these methods applied to recycling heavy metals and organics from several kinds of e-wastes. The method principle, equipment used, separating process, optimized operating parameters and recycling mechanism of each case are illustrated in details. The perspectives on the further development of e-wastes recycling by VMS are also presented.

Effect of surfactant concentration on the evaporation of droplets on cotton (Gossypium hirsutum L.) leaves.

PubMed

Zhou, Zhaolu; Cao, Chong; Cao, Lidong; Zheng, Li; Xu, Jun; Li, Fengmin; Huang, Qiliang

2018-04-05

The evaporation kinetics of pesticide droplets deposited on a leaf surface can affect their application efficiency. Evaporation of droplets on the hydrophobic leaves has received considerable attention, but little is known about hydrophilic leaf surfaces. In this study, the effect of surfactant concentration on the evaporation of droplets deposited on cotton leaves was investigated. The evaporation time is roughly decreased for concentrations ranging from 0% to 0.01% and increased from 0.01% to 0.10%. Contrary to the widely held belief that pesticide retention on target crops can rapidly be formed only with surfactant concentrations exceeding the CMC (critical micelle concentration), this study demonstrates that, on hydrophilic cotton leaves, fast evaporation of the droplet at surfactant concentrations of 0.01% (CMC) can reduce the volume quickly, lower the loss point and enhance pesticide retention. In addition, the evolution of droplet volume, height and contact angle on the cotton leaf surface were measured to confirm this conclusion. The result presented herein can be used to guide the use of surfactants and pesticides in agriculture. Copyright © 2018 Elsevier B.V. All rights reserved.

Experimental Studies of Spray Deposition on a Flat Surface in a Vacuum Environment

NASA Technical Reports Server (NTRS)

Golliher, Eric L.; Yao, S. C.

2015-01-01

Cooling of spacecraft components in the space environment is an on-going research effort. The electronics used in modern spacecraft are always changing and the heat flux is increasing. New, one-of-a-kind missions require new approaches to thermal control. In this research, under vacuum conditions, a pulsed water spray impinged on a small disc, while a high speed data acquisition system recorded the temperature histories of this copper disc. The water droplets froze quickly and accumulated on the disc as the spray continued. After the spray stopped, the frozen water that remained on the disc then sublimated into the vacuum environment and cooled the disc. This paper examines two important aspects of this process: 1) the difference in spray start up and shutdown in a vacuum environment versus in a standard atmospheric pressure environment, and 2) the water utilization efficiency in a vacuum environment due to the effects of drop trajectories and drop bouncing on the surface. Both phenomena play a role during spray cooling in a vacuum. This knowledge should help spacecraft designers plan for spray cooling as an option to cool spacecraft electronics, human metabolic generated heat, and heat from other sources.

Vacuum pumps and systems: A review of current practice

NASA Technical Reports Server (NTRS)

Giles, Stuart

1986-01-01

A review of the fundamental characteristics of the many types of vacuum pumps and vacuum pumping systems is given. The optimum pumping range, relative cost, performance limitations, maintenance problems, system operating costs and similar subjects are discussed. Experiences from the thin film deposition, chemical processing, material handling, food processing and other industries, as well as space simulation are used to support conclusions and recommendations.

Deposition and characterization of aluminum magnesium boride thin film coatings

NASA Astrophysics Data System (ADS)

Tian, Yun

Boron-rich borides are a special group of materials possessing complex structures typically comprised of B12 icosahedra. All of the boron-rich borides sharing this common structural unit exhibit a variety of exceptional physical and electrical properties. In this work, a new ternary boride compound AlMgB14, which has been extensively studied in bulk form due to its novel mechanical properties, was fabricated into thin film coatings by pulsed laser deposition (PLD) technology. The effect of processing conditions (laser operating modes, vacuum level, substrate temperature, and postannealing, etc.) on the composition, microstructure evolution, chemical bonding, and surface morphology of AlMgB14 thin film coatings has been investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectrometry; the mechanical, electrical, and optical properties of AlMgB14 thin films have been characterized by nanoindentation, four-point probe, van der Pauw Hall measurement, activation energy measurement, and UV-VIS-NIR spectrophotometer. Experimental results show that AlMgB14 films deposited in the temperature range of 300 K - 873 K are amorphous. Depositions under a low vacuum level (5 x 10-5 Torr) can introduce a significant amount of C and O impurities into AlMgB14 films and lead to a complex oxide glass structure. Orthorhombic AlMgB14 phase cannot be obtained by subsequent high temperature annealing. By contrast, the orthorhombic AlMgB 14 crystal structure can be attained via high temperature-annealing of AlMgB14 films deposited under a high vacuum level (< 3 x 10-6 Torr), accompanied by strong texture formation. Low vacuum level-as deposited AlMgB14 films have low hardness (10 GPa), but high vacuum level-as deposited AlMgB14 films exhibit an extremely high hardness (45 GPa - 51 GPa), and the higher deposition temperature results in still higher hardness

Niobium tunnel junction fabrication using e-gun evaporation and SNAP

NASA Astrophysics Data System (ADS)

Kortlandt, J.; van der Zant, H. S. J.; Schellingerhout, A. J. G.; Mooij, J. E.

1990-11-01

We have fabricated high quality small area Nb-Al-Al 2O 3-Nb junctions with SNAP, making use of e-beam evaporation in a 10 -5 Pa diffusion pumped vacuum system. Nominal dimensions of the junctions are 8x8, 4x4 and 2x2 μm 2. We obtain typical current densities of 5-6 × 10 +2A/cm 2 and (critical current) x (subgap resistance) products of 40 mV.

Evidence of room temperature ferromagnetism in argon/oxygen annealed TiO2 thin films deposited by electron beam evaporation technique

NASA Astrophysics Data System (ADS)

Mohanty, P.; Kabiraj, D.; Mandal, R. K.; Kulriya, P. K.; Sinha, A. S. K.; Rath, Chandana

2014-04-01

TiO2 thin films deposited by electron beam evaporation technique annealed in either O2 or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O2 atmosphere. While the pristine film shows a super-paramagnetic behavior, both O2 and Ar annealed films display hysteresis at 300 K. X-ray photo emission spectroscopy (XPS), Raman spectroscopy, Rutherford's backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were used to refute the possible role of impurities/contaminants in magnetic properties of the films. The saturation magnetization of the O2 annealed film is found to be higher than the Ar annealed one. It is revealed from shifting of O 1s and Ti 2p core level spectra as well as from the enhancement of high binding energy component of O 1s spectra that the higher magnetic moment is associated with higher oxygen vacancies. In addition, O2 annealed film demonstrates better crystallinity, uniform deposition and smoother surface than that of the Ar annealed one from glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM). We conclude that although ferromagnetism is due to oxygen vacancies, the higher magnetization in O2 annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO2 film deposited by pulsed laser deposition (Mohanty et al., 2012 [10]).

Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stutzman, M L; Adderley, P; Brittian, J

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower partmore » of the UHV range. Measured NEG pump speed is high at pressures above 5×10 -11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.« less

Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition

PubMed Central

Wang, Rui; Lu, Fen; Fan, Wei Jun; Liu, Chong Yang; Loh, Ter-Hoe; Nguyen, Hoai Son; Narayanan, Balasubramanian

2007-01-01

Si/Si0.66Ge0.34coupled quantum well (CQW) structures with different barrier thickness of 40, 4 and 2 nm were grown on Si substrates using an ultra high vacuum chemical vapor deposition (UHV-CVD) system. The samples were characterized using high resolution x-ray diffraction (HRXRD), cross-sectional transmission electron microscopy (XTEM) and photoluminescence (PL) spectroscopy. Blue shift in PL peak energy due to interwell coupling was observed in the CQWs following increase in the Si barrier thickness. The Si/SiGe heterostructure growth process and theoretical band structure model was validated by comparing the energy of the no-phonon peak calculated by the 6 + 2-bandk·pmethod with experimental PL data. Close agreement between theoretical calculations and experimental data was obtained.

Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 3, May 1-July 31, 1981

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bube, R.H.

1981-01-01

Preparation of the hot-wall vacuum deposition system nears completion and the first trial evaporation should take place in mid October. A UTI 100C Mass Analyzer with a 1 to 300 AMU capability has been ordered for the system. Preliminary tests indicate good temperature tracking between the furnace core and the CdTe source itself. Homojunction cells prepared by HWVE deposition of n-CdTe on p-CdTe substrates in October 1980 show no significant change in dark or light properties after open-circuit storage for the next 9 months. CdTe single crystal boules have been grown with P, As and Cs impurity. For P impuritymore » it appears from our data that the segregation coefficient is close to unity, that the value of hole density is controlled by the P and not by some unknown background acceptor, and that growth with excess Cd gives slightly higher values of hole density than growth with excess Te. CdTe:As crystals appear similar to CdTe:P crystals.« less

Adjuvant Effects on Evaporation Rates and Wetted Area of Droplets on Waxy Leaves

USDA-ARS?s Scientific Manuscript database

The use of an appropriate adjuvant for pesticide applications is a critical process to improve spray deposit characteristics on waxy leaves and to reduce off-target losses. After deposition and evaporation, residue patterns of 500 µm sessile droplets that incorporated four classes of adjuvants on fi...

Method and apparatus for scientific analysis under low temperature vacuum conditions

DOEpatents

Winefordner, James D.; Jones, Bradley T.

1990-01-01

A method and apparatus for scientific analysis of a sample under low temperature vacuum conditions uses a vacuum chamber with a conveyor belt disposed therein. One end of the conveyor belt is a cool end in thermal contact with the cold stage of a refrigerator, whereas the other end of the conveyor belt is a warm end spaced from the refrigerator. A septum allows injection of a sample into the vacuum chamber on top of the conveyor belt for spectroscopic or other analysis. The sample freezes on the conveyor belt at the cold end. One or more windows in the vacuum chamber housing allow spectroscopic analysis of the sample. Following the spectroscopic analysis, the conveyor belt may be moved such that the sample moves toward the warm end of the conveyor belt where upon it evaporates, thereby cleaning the conveyor belt. Instead of injecting the sample by way of a septum and use of a syringe and needle, the present device may be used in series with capillary-column gas chromatography or micro-bore high performance liquid chromatography.

Role of molecular conformations in rubrene polycrystalline films growth from vacuum deposition at various substrate temperatures

NASA Astrophysics Data System (ADS)

Lin, Ku-Yen; Wang, Yan-Jun; Chen, Ko-Lun; Ho, Ching-Yuan; Yang, Chun-Chuen; Shen, Ji-Lin; Chiu, Kuan-Cheng

2017-01-01

We report on the optical and structural characterization of rubrene polycrystalline films fabricated from vacuum deposition with various substrate temperatures (Tsub). Depending on Tsub, the role of twisted and planar rubrene conformational isomers on the properties of rubrene films is focused. The temperature (T)-dependent inverse optical transmission (IOT) and photoluminescence (PL) spectra were performed on these rubrene films. The origins of these IOT and PL peaks are explained in terms of the features from twisted and planar rubrene molecules and of the band characteristics from rubrene molecular solid films. Here, two rarely reported weak-peaks at 2.431 and 2.605 eV were observed from IOT spectra, which are associated with planar rubrene. Besides, the T-dependence of optical bandgap deduced from IOT spectra is discussed with respect to Tsub. Together with IOT and PL spectra, for Tsub > 170 °C, the changes in surface morphology and unit cell volume were observed for the first time, and are attributed to the isomeric transformation from twisted to planar rubrenes during the deposition processes. Furthermore, a unified schematic diagram in terms of Frenkel exciton recombination is suggested to explain the origins of the dominant PL peaks performed on these rubrene films at 15 K.

High-efficiency solar cells fabricated by vacuum MO-CVD

NASA Technical Reports Server (NTRS)

Fraas, L. M.; Cape, J. A.; Partain, L. D.; Mcleod, P. S.

1984-01-01

High-efficiency, monolithic, two-color, three-terminal solar cells were fabricated by a novel growth technique, vacuum metal-organic chemical vapor deposition. The technique uses the expensive metal alkyls efficiently and toxic gases sparingly. The fact that the outer chamber is constructed of nonbreakable stainless steel is an attractive safety feature associated with this deposition system.

Deposition pattern and tracer particle motion of evaporating multi-component sessile droplets.

PubMed

Amjad, Muhammad; Yang, Yang; Raza, Ghulam; Gao, Hui; Zhang, Jun; Zhou, Leping; Du, Xiaoze; Wen, Dongsheng

2017-11-15

The understanding of near-wall motion, evaporation behavior and dry pattern of sessile nanofluid droplets is fundamental to a wide range of applications such as painting, spray drying, thin film coating, fuel injection and inkjet printing. However, a deep insight into the heat transfer, fluid flow, near-wall particle velocity and their effects on the resulting dry patterns is still much needed to take the full advantage of these nano-sized particles in the droplet. This work investigates the effect of direct absorptive silicon/silver (Si/Ag) hybrid nanofluids via two experiments. The first experiment identifies the motion of tracer particles near the triple line of a sessile nanofluid droplet on a super-hydrophilic substrate under ambient conditions by the multilayer nanoparticle image velocimetry (MnPIV) technique. The second experiment reveals the effect of light-sensitive Si/Ag composite nanoparticles on the droplet evaporation rate and subsequent drying patterns under different radiation intensities. The results show that the presence of nanoparticle in a very small proportion significantly affects the motion of tracer particles, leading to different drying patterns and evaporation rates, which can be very important for the applications such as spray coating and inkjet printing. Copyright © 2017 Elsevier Inc. All rights reserved.

[Interlaboratory Study on Evaporation Residue Test for Food Contact Products (Report 2)].

PubMed

Ohno, Hiroyuki; Mutsuga, Motoh; Abe, Tomoyuki; Abe, Yutaka; Amano, Homare; Ishihara, Kinuyo; Ohsaka, Ikue; Ohno, Haruka; Ohno, Yuichiro; Ozaki, Asako; Kakihara, Yoshiteru; Kobayashi, Hisashi; Sakuragi, Hiroshi; Shibata, Hiroshi; Shirono, Katsuhiro; Sekido, Haruko; Takasaka, Noriko; Takenaka, Yu; Tajima, Yoshiyasu; Tanaka, Aoi; Tanaka, Hideyuki; Nakanishi, Toru; Nomura, Chie; Haneishi, Nahoko; Hayakawa, Masato; Miura, Toshihiko; Yamaguchi, Miku; Yamada, Kyohei; Watanabe, Kazunari; Sato, Kyoko

2018-01-01

An interlaboratory study was performed to evaluate the equivalence between an official method and a modified method of evaporation residue test using heptane as a food-simulating solvent for oily or fatty foods, based on the Japanese Food Sanitation Law for food contact products. Twenty-three laboratories participated, and tested the evaporation residues of nine test solutions as blind duplicates. In the official method, heating for evaporation was done with a water bath. In the modified method, a hot plate was used for evaporation, and/or a vacuum concentration procedure was skipped. In most laboratories, the test solutions were heated until just prior to dryness, and then allowed to dry under residual heat. Statistical analysis revealed that there was no significant difference between the two methods. Accordingly, the modified method provides performance equal to the official method, and is available as an alternative method. Furthermore, an interlaboratory study was performed to evaluate and compare two leaching solutions (95% ethanol and isooctane) used as food-simulating solvents for oily or fatty foods in the EU. The results demonstrated that there was no significant difference between heptane and these two leaching solutions.

Fluoride coatings for vacuum ultraviolet reflection filters.

PubMed

Guo, Chun; Kong, Mingdong; Lin, Dawei; Li, Bincheng

2015-12-10

LaF3/MgF2 reflection filters with a high spectral-discrimination capacity of the atomic-oxygen lines at 130.4 and 135.6 nm, which were employed in vacuum ultraviolet imagers, were prepared by molybdenum-boat thermal evaporation. The optical properties of reflection filters were characterized by a high-precision vacuum ultraviolet spectrophotometer. The vulnerability of the filter's microstructures to environmental contamination and the recovery of the optical properties of the stored filter samples with ultraviolet ozone cleaning were experimentally demonstrated. For reflection filters with the optimized nonquarter-wave multilayer structures, the reflectance ratios R135.6 nm/R130.4 nm of 92.7 and 20.6 were achieved for 7° and 45° angles of incidence, respectively. On the contrary, R135.6 nm/R130.4 nm ratio of 12.4 was obtained for a reflection filter with a standard π-stack multilayer structure with H/L=1/4 at 7° AOI.

Transition from stripe-like patterns to a particulate film using driven evaporating menisci.

PubMed

Noguera-Marín, Diego; Moraila-Martínez, Carmen L; Cabrerizo-Vílchez, Miguel A; Rodríguez-Valverde, Miguel A

2014-07-01

Better control of colloidal assembly by convective deposition is particularly helpful in particle templating. However, knowledge of the different factors that can alter colloidal patterning mechanisms is still insufficient. Deposit morphology is strongly ruled by contact line dynamics, but the wettability properties of the substrate can alter it drastically. In this work, we experimentally examined the roles of substrate contact angle hysteresis and receding contact angle using driven evaporating menisci similar to the dip-coating technique but at a low capillary number. We used smooth substrates with very different wettability properties and nanoparticles of different sizes. For fixed withdrawal velocity, evaporation conditions, and nanoparticle concentration, we analyzed the morphology of the deposits formed on each substrate. A gradual transition from stripe-like patterns to a film was observed as the contact angle hysteresis and receding contact angle were lowered.

Atomic layer deposition and etching methods for far ultraviolet aluminum mirrors

NASA Astrophysics Data System (ADS)

Hennessy, John; Moore, Christopher S.; Balasubramanian, Kunjithapatham; Jewell, April D.; Carter, Christian; France, Kevin; Nikzad, Shouleh

2017-09-01

High-performance aluminum mirrors at far ultraviolet wavelengths require transparent dielectric materials as protective coatings to prevent oxidation. Reducing the thickness of this protective layer can result in additional performance gains by minimizing absorption losses, and provides a path toward high Al reflectance in the challenging wavelength range of 90 to 110 nm. We have pursued the development of new atomic layer deposition processes (ALD) for the metal fluoride materials of MgF2, AlF3 and LiF. Using anhydrous hydrogen fluoride as a reactant, these films can be deposited at the low temperatures required for large-area surface-finished optics and polymeric diffraction gratings. We also report on the development and application of an atomic layer etching (ALE) procedure to controllably etch native aluminum oxide. Our ALE process utilizes the same chemistry used in the ALD of AlF3 thin films, allowing for a combination of high-performance evaporated Al layers and ultrathin ALD encapsulation without requiring vacuum transfer. Progress in demonstrating the scalability of this approach, as well as the environmental stability of ALD/ALE Al mirrors are discussed in the context of possible future applications for NASA LUVOIR and HabEx mission concepts.

Development of chemically vapor deposited rhenium emitters of (0001) preferred crystal orientation

NASA Technical Reports Server (NTRS)

Yang, L.; Hudson, R. G.

1973-01-01

Rhenium thermionic emitters were prepared by the pyrolysis of rhenium chlorides formed by the chlorination of rhenium pellets. The impurity contents, microstructures, degrees of (0001) preferred crystal orientation, and vacuum electron work functions of these emitters were determined as a function of deposition parameters, such as substrate temperature, rhenium pellet temperature and chlorine flow rate. A correlation between vacuum electron work function and degree of (0001) preferred crystal orientation was established. Conditions for depositing porosity-free rhenium emitters of high vacuum electron work functions were defined. Finally, three cylindrical rhenium emitters were prepared under the optimum deposition conditions.

A vacuum-sealed, gigawatt-class, repetitively pulsed high-power microwave source

NASA Astrophysics Data System (ADS)

Xun, Tao; Fan, Yu-wei; Yang, Han-wu; Zhang, Zi-cheng; Chen, Dong-qun; Zhang, Jian-de

2017-06-01

A compact L-band sealed-tube magnetically insulated transmission line oscillator (MILO) has been developed that does not require bulky external vacuum pump for repetitive operations. This device with a ceramic insulated vacuum interface, a carbon fiber array cathode, and non-evaporable getters has a base vacuum pressure in the low 10-6 Pa range. A dynamic 3-D Monte-Carlo model for the molecular flow movement and collision was setup for the MILO chamber. The pulse desorption, gas evolution, and pressure distribution were exactly simulated. In the 5 Hz repetition rate experiments, using a 600 kV diode voltage and 48 kA beam current, the average radiated microwave power for 25 shots is about 3.4 GW in 45 ns pulse duration. The maximum equilibrium pressure is below 4.0 × 10-2 Pa, and no pulse shortening limitations are observed during the repetitive test in the sealed-tube condition.

Structural and optical properties of CuS thin films deposited by Thermal co-evaporation

NASA Astrophysics Data System (ADS)

Sahoo, A. K.; Mohanta, P.; Bhattacharyya, A. S.

2015-02-01

Copper sulfide (CuS) thin films with thickness 100, 150 and 200 nm have been deposited on glass substrates by thermal co-evaporation of Copper and Sulphur. The effect of CuS film thickness on the structural and optical properties have investigated and discussed. Structural and optical investigations of the films were carried out by X-ray diffraction, atomic force microscopy, high-resolution transmission electron microscopy and UV spectroscopy. XRD and selected area electron diffraction conforms that polycrystalline in nature with hexagonal crystal structure. AFM studies revealed a smooth surface morphology with root mean-square roughness values increases from 24 nm to 42 nm as the film thickness increase from 100 nm to 200 nm. AFM image showed that grain size increases with thickness of film increases and good agreement with the calculated from full width half maximum of the X-ray diffraction peak using Scherrer's formula and Williamson-Hall plot. The absorbance of the thin films were absorbed decreases with wavelength through UV-visible regions but showed a increasing in the near-infrared regions. The reflectance spectra also showed lower reflectance peak (25% to 32%) in visible region and high reflectance peak (49 % to 54 %) in near-infrared region. These high absorbance films made them for photo-thermal conversion of solar energy.

The Pulsed Cylindrical Magnetron for Deposition

NASA Astrophysics Data System (ADS)

Korenev, Sergey

2012-10-01

The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.

Mass-spring matching layers for high-frequency ultrasound transducers: a new technique using vacuum deposition.

PubMed

Brown, Jeremy; Sharma, Srikanta; Leadbetter, Jeff; Cochran, Sandy; Adamson, Rob

2014-11-01

We have developed a technique of applying multiple matching layers to high-frequency (>30 MHz) imaging transducers, by using carefully controlled vacuum deposition alone. This technique uses a thin mass-spring matching layer approach that was previously described in a low-frequency (1 to 10 MHz) transducer design with epoxied layers. This mass- spring approach is more suitable to vacuum deposition in highfrequency transducers over the conventional quarter-wavelength resonant cavity approach, because thinner layers and more versatile material selection can be used, the difficulty in precisely lapping quarter-wavelength matching layers is avoided, the layers are less attenuating, and the layers can be applied to a curved surface. Two different 3-mm-diameter 45-MHz planar lithium niobate transducers and one geometrically curved 3-mm lithium niobate transducer were designed and fabricated using this matching layer approach with copper as the mass layer and parylene as the spring layer. The first planar lithium niobate transducer used a single mass-spring matching network, and the second planar lithium niobate transducer used a single mass-spring network to approximate the first layer in a dual quarter-wavelength matching layer system in addition to a conventional quarter-wavelength layer as the second matching layer. The curved lithium niobate transducer was press focused and used a similar mass-spring plus quarter-wavelength matching layer network. These transducers were then compared with identical transducers with no matching layers and the performance improvement was quantified. The bandwidth of the lithium niobate transducer with the single mass-spring layer was measured to be 46% and the insertion loss was measured to be -21.9 dB. The bandwidth and insertion loss of the lithium niobate transducer with the mass-spring network plus quarter-wavelength matching were measured to be 59% and -18.2 dB, respectively. These values were compared with the unmatched

The influence of defects and impurities on the nucleation and growth of oriented films by evaporation

NASA Technical Reports Server (NTRS)

Green, A. K.

1973-01-01

The influence of substrate imperfections on the nucleation and growth of fcc metals on alkali halides is discussed. Films deposited on well characterized substrated under well defined vacuum evaporation conditions are investigated. The experimental results of this work are correlated with similar work by other investigators. Models which have been proposed by various authors to explain experimental results are critically examined and areas of difficulty are pointed out. The influence of defects on nucleation rate and the orientation of the film is emphasized. Specific examples of impurity effects, irradiation effects and the influence of amorphous layers are discussed in detail. Evidence is shown that the formation of multiply twinned particles is a result of coalescence and growth. The only consistent model for the orienting influence of impurities is shown to be a chemical reaction effect. It is demonstrated that an alkali metal impurity is very likely responsible for the orienting influence of both water vapor exposure and irradiation. A negative result is found for the reported possibility of an orienting influence being transmitted through an amorphous layer.

The influence of titanium adhesion layer oxygen stoichiometry on thermal boundary conductance at gold contacts

NASA Astrophysics Data System (ADS)

Olson, David H.; Freedy, Keren M.; McDonnell, Stephen J.; Hopkins, Patrick E.

2018-04-01

We experimentally demonstrate the role of oxygen stoichiometry on the thermal boundary conductance across Au/TiOx/substrate interfaces. By evaporating two different sets of Au/TiOx/substrate samples under both high vacuum and ultrahigh vacuum conditions, we vary the oxygen composition in the TiOx layer from 0 ≤ x ≤ 2.85. We measure the thermal boundary conductance across the Au/TiOx/substrate interfaces with time-domain thermoreflectance and characterize the interfacial chemistry with x-ray photoemission spectroscopy. Under high vacuum conditions, we speculate that the environment provides a sufficient flux of oxidizing species to the sample surface such that one essentially co-deposits Ti and these oxidizing species. We show that slower deposition rates correspond to a higher oxygen content in the TiOx layer, which results in a lower thermal boundary conductance across the Au/TiOx/substrate interfacial region. Under the ultrahigh vacuum evaporation conditions, pure metallic Ti is deposited on the substrate surface. In the case of quartz substrates, the metallic Ti reacts with the substrate and getters oxygen, leading to a TiOx layer. Our results suggest that Ti layers with relatively low oxygen compositions are best suited to maximize the thermal boundary conductance.

Deposition of Boron in Possible Evaporite Deposits in Gale Crate

NASA Astrophysics Data System (ADS)

Gasda, P. J.; Peets, E.; Lamm, S. N.; Rapin, W.; Lanza, N.; Frydenvang, J.; Clark, B. C.; Herkenhoff, K. E.; Bridges, J.; Schwenzer, S. P.; Haldeman, E. B.; Wiens, R. C.; Maurice, S.; Clegg, S. M.; Delapp, D.; Sanford, V.; Bodine, M. R.; McInroy, R.

2017-12-01

Boron has been previously detected in Gale crater using the ChemCam instrument on board the NASA Curiosity rover within calcium sulfate fracture fill hosted by lacustrine mudstone and eolian sandstone units. Recent results show that up to 300 ppm B is present in the upper sections of the lacustrine unit. Boron has been detected in both the groundwater-emplaced calcium sulfate fracture fill materials and bedding-parallel calcium sulfate layers. The widespread bedding-parallel calcium sulfate layers within the upper strata of the lacustrine bedrock that Curiosity has encountered recently could be interpreted as primary evaporite deposits. We have two hypotheses for the history of boron in Gale crater. In both hypotheses, borates were first deposited as lake water evaporated, depositing primary evaporates that were later re-dissolved by groundwater, which redistributed the boron into secondary evaporitic calcium sulfate fracture fill deposits. In the first scenario, Gale crater may have undergone a period of perennial lake formation during a drier period of martian history, depositing layers of evaporitic minerals (including borates) among lacustrine mudstone layers. In the second scenario, lake margins could have become periodically exposed during cyclic drops in lake level and subsequently desiccated. Evaporites were deposited and desiccation features were formed in lowstand deposits. Either hypothetical scenario of evaporite deposition would promote prebiotic chemical reactions via wet-dry cycles. Boron may be an important prebiotic element, and as such, its presence in ancient martian surface and groundwater provides evidence that important prebiotic chemical reactions could occur on Mars if organics were present. The presence of boron in ancient Gale crater groundwater also provides additional evidence that a habitable environment existed in the martian subsurface well after the expected disappearance of liquid water on the surface of Mars. We will report on the

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

NASA Astrophysics Data System (ADS)

Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling.

PubMed

Donnarumma, Fabrizio; Camp, Eden E; Cao, Fan; Murray, Kermit K

2017-09-01

Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. Graphical Abstract ᅟ.

Droplet evaporation on a horizontal substrate under gravity field by mesoscopic modeling.

PubMed

Xie, Chiyu; Zhang, Jianying; Bertola, Volfango; Wang, Moran

2016-02-01

The evaporation of water drop deposited on a horizontal substrate is investigated using a lattice Boltzmann method (LBM) for multiphase flows with a large-density ratio. To account for the variation of evaporation flux distribution along the drop interface, a novel evaporation scheme is introduced into the LBM framework, and validated by comparison with experimental data. We aim at discovering the effect of gravity on the evaporating drop in detail, and various evaporation conditions are considered as well as different wetting properties of the substrates. An effective diameter is introduced as an indicator of the critical drop size under which gravity is negligible. Our results show that such critical diameter is much smaller than the capillary length, which has been widely accepted as the critical size in previous and current works. The critical diameter is found to be almost independent of the evaporation conditions and the surface wettability. A correlation between this critical diameter and the capillary length is also proposed for easy use in applications. Copyright © 2015 Elsevier Inc. All rights reserved.

Heat transfer in a liquid helium cooled vacuum tube following sudden vacuum loss

NASA Astrophysics Data System (ADS)

Dhuley, R. C.; Van Sciver, S. W.

2015-12-01

Condensation of nitrogen gas rapidly flowing into a liquid helium (LHe) cooled vacuum tube is studied. This study aims to examine the heat transfer in geometries such as the superconducting RF cavity string of a particle accelerator following a sudden loss of vacuum to atmosphere. In a simplified experiment, the flow is generated by quickly venting a large reservoir of nitrogen gas to a straight long vacuum tube immersed in LHe. Normal LHe (LHe I) and superfluid He II are used in separate experiments. The rate of condensation heat transfer is determined from the temperature of the tube measured at several locations along the gas flow. Instantaneous heat deposition rates in excess of 200 kW/m2 result from condensation of the flowing gas. The gas flow is then arrested in its path to pressurize the tube to atmosphere and estimate the heat transfer rate to LHe. A steady LHe I heat load of ≈25 kW/m2 is obtained in this scenario. Observations from the He II experiment are briefly discussed. An upper bound for the LHe I heat load is derived based on the thermodynamics of phase change of nitrogen.

Adjuvant Effects on Evaporation Time and Wetted Area of Droplets

USDA-ARS?s Scientific Manuscript database

Appropriate adjuvant selection for pesticide applications is central to improve spray performances on waxy leaves and to reduce off-target losses. Evaporation and deposition patterns of 500 µm sessile droplets with five classes of adjuvants on five different waxy plants were investigated. Droplets g...

Investigation of TiN thin film oxidation depending on the substrate temperature at vacuum break

DOE Office of Scientific and Technical Information (OSTI.GOV)

Piallat, Fabien, E-mail: fabien.piallat@gmail.com; CEA, LETI, Campus Minatec, F-38054 Grenoble; LTM-CNRS, 17 rue des Martyrs, 38054 Grenoble

2016-09-15

Due to the reduction of the thickness of the layers used in the advanced technology nodes, there is a growing importance of the surface phenomena in the definition of the general properties of the materials. One of the least controlled and understood phenomenon is the oxidation of metals after deposition, at the vacuum break. In this study, the influence of the sample temperature at vacuum break on the oxidation level of TiN deposited by metalorganic chemical vapor deposition is investigated. TiN resistivity appears to be lower for samples which underwent vacuum break at high temperature. Using X-ray photoelectron spectrometry analysis,more » this change is correlated to the higher oxidation of the TiN layer. Moreover, angle resolved XPS analysis reveals that higher is the temperature at the vacuum break, higher is the surface oxidation of the sample. This surface oxidation is in turn limiting the diffusion of oxygen in the volume of the layer. Additionally, evolution of TiN layers resistivity was monitored in time and it shows that resistivity increases until a plateau is reached after about 10 days, with the lowest temperature at vacuum break resulting in the highest increase, i.e., the resistivity of the sample released to atmosphere at high temperature increased by a factor 1.7 whereas the resistivity of the sample cooled down under vacuum temperature increased by a factor 2.7.« less

[Effects of the grain size and thickness of dust deposits on soil water and salt movement in the hinterland of the Taklimakan Desert].

PubMed

Sun, Yan-Wei; Li, Sheng-Yu; Xu, Xin-Wen; Zhang, Jian-Guo; Li, Ying

2009-08-01

By using mcirolysimeter, a laboratory simulation experiment was conducted to study the effects of the grain size and thickness of dust deposits on the soil water evaporation and salt movement in the hinterland of the Taklimakan Desert. Under the same initial soil water content and deposition thickness condition, finer-textured (<0.063 mm) deposits promoted soil water evaporation, deeper soil desiccation, and surface soil salt accumulation, while coarse-textured (0.063-2 mm) deposits inhibited soil water evaporation and decreased deeper soil water loss and surface soil salt accumulation. The inhibition effect of the grain size of dust deposits on soil water evaporation had an inflection point at the grain size 0.20 mm, i. e., increased with increasing grain size when the grain size was 0.063-0.20 mm but decreased with increasing grain size when the grain size was > 0.20 mm. With the increasing thickness of dust deposits, its inhibition effect on soil water evaporation increased, and there existed a logarithmic relationship between the dust deposits thickness and water evaporation. Surface soil salt accumulation had a negative correlation with dust deposits thickness. In sum, the dust deposits in study area could affect the stability of arid desert ecosystem.

2017 Report for New LANL Physical Vapor Deposition Capability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roman, Audrey Rae; Zhao, Xinxin; Bond, Evelyn M.

There is an urgent need at LANL to achieve uniform, thin film actinide targets that are essential for nuclear physics experiments. The target preparation work is currently performed externally by Professor Walter Loveland at Oregon State University, who has made various evaporated actinide targets such as Th and U for use on several nuclear physics measurements at LANSCE. We are developing a vapor deposition capability, with the goal of evaporating Th and U in the Actinide Research Facility (ARF) at TA-48. In the future we plan to expand this work to evaporating transuranic elements, such as Pu. The ARF ismore » the optimal location for evaporating actinides because this lab is specifically dedicated to actinide research. There are numerous instruments in the ARF that can be used to provide detailed characterization of the evaporated thin films such as: Table top Scanning Electron Microscope, In-situ X-Ray Diffraction, and 3D Raman spectroscopy. These techniques have the ability to determine the uniformity, surface characterization, and composition of the deposits.« less

[Effect of vacuum deposition technology on the metal-porcelain bond strength of a new type of CO-CR ceramic and framework dental alloy].

PubMed

Wu, Jun-ling; Chao, Yong-lie; Ji, Ping; Gao, Xu

2007-10-01

To investigate the effect of a new engineering technique of vacuum deposition-plasma magnetron reactive sputter deposition technique on the metal-porcelain bond strength of a new type of Co-Cr ceramic and framework dental alloy. Before porcelain painted on the specimens, the standardized metal strips made from DA9-4 dental alloy were coated with a thin Al2O3 ceramic film by plasma magnetron reactive sputter deposition technique. The conformation, structure and thickness of the ceramic film were analyzed. The specimens for three-point bending test made from DA9-4 alloy and VMK95 porcelain were used for metal-porcelain bond strength measurement, in the same time the interface of metal-porcelain and element distribution were also observed. The flexural bonding strength of metal-porcelain of sputtering group and control group were (180.55+/-16.45) MPa and (143.80+/-24.49) MPa. The flexural bonding strength of metal-porcelain of sputtering group was higher than control group significantly through statistical analysis (P<0.01). The plasma magnetron reactive sputter deposition technique has a positive effect in improving the bonding strength of DA9-4 dental alloy and ceramic.

Large-aperture plasma-assisted deposition of inertial confinement fusion laser coatings.

PubMed

Oliver, James B; Kupinski, Pete; Rigatti, Amy L; Schmid, Ansgar W; Lambropoulos, John C; Papernov, Semyon; Kozlov, Alexei; Spaulding, John; Sadowski, Daniel; Chrzan, Z Roman; Hand, Robert D; Gibson, Desmond R; Brinkley, Ian; Placido, Frank

2011-03-20

Plasma-assisted electron-beam evaporation leads to changes in the crystallinity, density, and stresses of thin films. A dual-source plasma system provides stress control of large-aperture, high-fluence coatings used in vacuum for substrates 1m in aperture.

Hydrogen capacity and absorption rate of the SAES St707 non-evaporable getter at various temperatures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Irving; Mills, Bernice E.

2010-08-01

A prototype of a tritium thermoelectric generator (TTG) is currently being developed at Sandia. In the TTG, a vacuum jacket reduces the amount of heat lost from the high temperature source via convection. However, outgassing presents challenges to maintaining a vacuum for many years. Getters are chemically active substances that scavenge residual gases in a vacuum system. In order to maintain the vacuum jacket at approximately 1.0 x 10{sup -4} torr for decades, nonevaporable getters that can operate from -55 C to 60 C are going to be used. This paper focuses on the hydrogen capacity and absorption rate ofmore » the St707{trademark} non-evaporable getter by SAES. Using a getter testing manifold, we have carried out experiments to test these characteristics of the getter over the temperature range of -77 C to 60 C. The results from this study can be used to size the getter appropriately.« less

High-Capacity Spacesuit Evaporator Absorber Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, Gregory

2015-01-01

Future human space exploration missions will require advanced life support technology that can operate across a wide range of applications and environments. Thermal control systems for space suits and spacecraft will need to meet critical requirements for water conservation and multifunctional operation. This paper describes a Space Evaporator Absorber Radiator (SEAR) that has been designed to meet performance requirements for future life support systems. A SEAR system comprises a lithium chloride absorber radiator (LCAR) for heat rejection coupled with a space water membrane evaporator (SWME) for heat acquisition. SEAR systems provide heat pumping to minimize radiator size, thermal storage to accommodate variable environmental conditions, and water absorption to minimize use of expendables. We have built and tested a flight-like, high-capacity LCAR, demonstrated its performance in thermal vacuum tests, and explored the feasibility of an ISS demonstration test of a SEAR system. The new LCAR design provides the same cooling capability as prior LCAR prototypes while enabling over 30% more heat absorbing capacity. Studies show that it should be feasible to demonstrate SEAR operation in flight by coupling with an existing EMU on the space station.

High-Capacity Spacesuit Evaporator Absorber Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Phillips, Scott; Chepko, Ariane; Bue, Grant; Quinn, Gregory

2014-01-01

Future human space exploration missions will require advanced life support technology that can operate across a wide range of applications and environments. Thermal control systems for space suits and spacecraft will need to meet critical requirements for water conservation and adaptability to highly variable thermal environments. This paper describes a Space Evaporator Absorber Radiator (SEAR) that has been designed to meet performance requirements for future life support systems. A SEAR system comprises a lithium chloride absorber radiator (LCAR) for heat rejection coupled with a space water membrane evaporator (SWME) for heat acquisition. SEAR systems provide heat pumping to minimize radiator size, thermal storage to accommodate variable environmental conditions, and water absorption to minimize use of expendables. We have built and tested a flightlike, high-capacity LCAR, demonstrated its performance in thermal vacuum tests, and explored the feasibility of an ISS demonstration test of a SEAR system. The new LCAR design provides the same cooling capability as prior LCAR prototypes while enabling over 30% more heat absorbing capacity. Studies show that it should be feasible to demonstrate SEAR operation in flight by coupling with an existing EMU on the space station.

Studies of Lubricating Materials in Vacuum

NASA Technical Reports Server (NTRS)

Buckley, D. H.; Johnson, R. L.; Swikert, M. A.

1964-01-01

Lubricating materials for use in a vacuum environment have been the subject of a series of experimental investigations. Evaporation properties were evaluated for solid polymeric compositions. Friction and wear studies explored the behavior during sliding contact for series of polymeric compositions, binary alloys containing soft film-forming phases, complex alloys with film-forming materials, and a burnished MoS2 film. Friction and wear experiments were conducted at 10(exp-9)mm Hg with a 3/16-inch-radius-hemisphere rider specimen sliding on the flat surface of a rotating 2-1/2-inch-diameter disk specimen with materials that had low rates of evaporation. The influence of fillers in polytetrafluoroethylene (PTFE) on decomposition during vacuum friction studies was determined with a mass spectrometer. A real advantage in reducing decomposition and improving friction wear properties is gained by adding fillers (e.g., copper) that improve thermal conductivity through the composite materials. A polyimide and an epoxy-MoS2 composition material were found to have better friction and wear properties than PTFE compositions. A series of alloys (cast binary as well as more complex alloys) that contained microinclusions of potential film-forming material was studied. These materials replaced the normal surface oxides as they were worn away on sliding contact. Iron sulfide, nickel oxide, and tin are typical film-forming materials employed and were demonstrated to be effective in inhibiting surface welding and reducing friction. A burnished MoS2 film applied to type 440-C stainless steel in argon with a rotating soft wire brush had good endurance properties but somewhat higher friction than commercially available bonded films. An oil film applied to the burnished MoS2 markedly reduced its endurance life.

Preparation of AgInSe2 thin films grown by vacuum evaporation method

NASA Astrophysics Data System (ADS)

Matsuo, H.; Yoshino, K.; Ikari, T.

2006-09-01

Polycrystalline AgInSe2 thin films were successfully grown on glass substrates by an evaporation method. The starting materials were stoichiometrically mixed Ag2Se and In2Se3 powders. X-ray diffraction revealed that the sample annealed at 600 °C consisted of AgInSe2 single phase, with (112) orientation and a large grain size. The lattice constant (a axis) was close to JCPDS values. From optical transmittance and reflectance measurements, the bandgap energy was estimated to be 1.17 eV.

Characterizations of the Core-Shell Structured MgB2/CARBON Fiber Synthesis by Rf-Sputtering and Thermal Evaporation

NASA Astrophysics Data System (ADS)

Park, Sung Chang; Lim, Yeong Jin; Lee, Tae-Keun; Kim, Cheol Jin

MgB2/carbon fibers have been synthesized by the combination of RF-sputtering of B and thermal evaporation of Mg, followed by co-evaporation. First, boron layer was deposited by RF-sputtering on the carbon fiber with average diameter of 7.1 μm. Later this coated layer of B was reacted with Mg vapor to transform into MgB2. Since the MgB2 reaction proceed with Mg diffusion into the boron layer, Mg vapor pressure and the diffusion time had to be controlled precisely to secure the complete reaction. Also the deposition rate of each element was controlled separately to obtain stoichiometric MgB2, since Mg was evaporated by thermal heating and B by sputtering system. The sintered B target was magnetron sputtered at the RF-power of ~200 W, which corresponded to the deposition rate of ~3.6 Å/s. With the deposition rate of B fixed, the vapor pressure of Mg was controlled by varying the temperature of tungsten boat with heating element control unit between 100 and 900°C. The MgB2 layers with the thickness of 200-950 nm could be obtained and occasionally MgO appeared as a second phase. Superconducting transition temperatures were measured around ~38 K depending on the deposition condition.

Testing of the Multi-Fluid Evaporator Engineering Development Unit

NASA Technical Reports Server (NTRS)

Quinn, Gregory; O'Connor, Ed; Riga, Ken; Anderson, Molly; Westheimer, David

2007-01-01

Hamilton Sundstrand is under contract with the NASA Johnson Space Center to develop a scalable, evaporative heat rejection system called the Multi-Fluid Evaporator (MFE). It is being designed to support the Orion Crew Module and to support future Constellation missions. The MFE would be used from Earth sea level conditions to the vacuum of space. The current Shuttle configuration utilizes an ammonia boiler and flash evaporator system to achieve cooling at all altitudes. The MFE system combines both functions into a single compact package with significant weight reduction and improved freeze-up protection. The heat exchanger core is designed so that radial flow of the evaporant provides increasing surface area to keep the back pressure low. The multiple layer construction of the core allows for efficient scale up to the desired heat rejection rate. The full scale MFE prototype will be constructed with four core sections that, combined with a novel control scheme, manage the risk of freezing the heat exchanger cores. A sub-scale MFE engineering development unit (EDU) has been built, and is identical to one of the four sections of a full scale prototype. The EDU has completed testing at Hamilton Sundstrand. The overall test objective was to determine the thermal performance of the EDU. The first set of tests simulated how each of the four sections of the prototype would perform by varying the chamber pressure, evaporant flow rate, coolant flow rate and coolant temperature. A second set of tests was conducted with an outlet steam header in place to verify that the outlet steam orifices prevent freeze-up in the core while also allowing the desired thermal turn-down ratio. This paper discusses the EDU tests and results.

Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

NASA Astrophysics Data System (ADS)

Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

2016-11-01

Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

Design challenges for matrix assisted pulsed laser evaporation and infrared resonant laser evaporation equipment

NASA Astrophysics Data System (ADS)

Greer, James A.

2011-11-01

Since the development of the Matrix Assisted Pulsed Laser Evaporation (MAPLE) process by the Naval Research Laboratory (NRL) in the late 1990s, MAPLE has become an active area of research for the deposition of a variety of polymer, biological, and organic thin films. As is often the case with advancements in thin-film deposition techniques new technology sometimes evolves by making minor or major adjustments to existing deposition process equipment and techniques. This is usually the quickest and least expensive way to try out new ideas and to "push the envelope" in order to obtain new and unique scientific results as quickly as possible. This process of "tweaking" current equipment usually works to some degree, but once the new process is further refined overall designs for a new deposition tool based on the critical attributes of the new process typically help capitalize more fully on the all the salient features of the new and improved process. This certainly has been true for the MAPLE process. In fact the first MAPLE experiments the polymer/solvent matrix was mixed and poured into a copper holder held at LN2 temperature on a laboratory counter top. The holder was then quickly placed onto a LN2 cooled reservoir in a vacuum deposition chamber and placed in a vertical position on a LN2 cooled stage and pumped down as quickly as possible. If the sample was not placed into the chamber quickly enough the frozen matrix would melt and drip into the bottom of the chamber onto the chambers main gate valve making a bit of a mess. However, skilled and motivated scientists usually worked quickly enough to make this process work most of the time. The initial results from these experiments were encouraging and led to several publications which sparked considerable interest in this newly developed technique Clearly this approach provided the vision that MAPLE was a viable deposition process, but the equipment was not optimal for conducting MAPLE experiments on a regular basis

DWPF RECYCLE EVAPORATOR FLOWSHEET EVALUATION (U)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stone, M

2005-04-30

The Defense Waste Processing Facility (DWPF) converts the high level waste slurries stored at the Savannah River Site into borosilicate glass for long-term storage. The vitrification process results in the generation of approximately five gallons of dilute recycle streams for each gallon of waste slurry vitrified. This dilute recycle stream is currently transferred to the H-area Tank Farm and amounts to approximately 1,400,000 gallons of effluent per year. Process changes to incorporate salt waste could increase the amount of effluent to approximately 2,900,000 gallons per year. The recycle consists of two major streams and four smaller streams. The first majormore » recycle stream is condensate from the Chemical Process Cell (CPC), and is collected in the Slurry Mix Evaporator Condensate Tank (SMECT). The second major recycle stream is the melter offgas which is collected in the Off Gas Condensate Tank (OGCT). The four smaller streams are the sample flushes, sump flushes, decon solution, and High Efficiency Mist Eliminator (HEME) dissolution solution. These streams are collected in the Decontamination Waste Treatment Tank (DWTT) or the Recycle Collection Tank (RCT). All recycle streams are currently combined in the RCT and treated with sodium nitrite and sodium hydroxide prior to transfer to the tank farm. Tank Farm space limitations and previous outages in the 2H Evaporator system due to deposition of sodium alumino-silicates have led to evaluation of alternative methods of dealing with the DWPF recycle. One option identified for processing the recycle was a dedicated evaporator to concentrate the recycle stream to allow the solids to be recycled to the DWPF Sludge Receipt and Adjustment Tank (SRAT) and the condensate from this evaporation process to be sent and treated in the Effluent Treatment Plant (ETP). In order to meet process objectives, the recycle stream must be concentrated to 1/30th of the feed volume during the evaporation process. The concentrated

Vacuum distillation: vapor filtered-catalytic oxidation water reclamation system utilizing radioisotopes

NASA Technical Reports Server (NTRS)

Honegger, R. J.; Remus, G. A.; Kurg, E. K.

1971-01-01

The development of a functional model water reclamation system is discussed. The system produces potable water by distillation from the urine and respiration-perspiration condensate at the normal rate generated by four men. Basic processes employed are vacuum distillation, vapor filtration, vapor phase catalytic oxidation, and condensation. The system is designed to use four 75-watt isotope heaters for distillation thermal input, and one 45-watt isotope for the catalytic oxidation unit. The system is capable of collecting and storing urine, and provides for stabilizing the urine by chemical pretreatment. The functional model system is designed for operation in a weightless condition with liquid-vapor phase separators for the evaporator still, and centrifugal separators for urine collection and vapor condensation. The system provides for storing and dispensing reclaimed potable water. The system operates in a batch mode for 40 days, with urine residues accumulating in the evaporator. The evaporator still and residue are removed to storage and replaced with a fresh still for the next 40-day period.

Vacuum system of the compact Energy Recovery Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honda, T., E-mail: tohru.honda@kek.jp; Tanimoto, Y.; Nogami, T.

2016-07-27

The compact Energy Recovery Linac (cERL), a test accelerator to establish important technologies demanded for future ERL-based light sources, was constructed in late 2013 at KEK. The accelerator was successfully commissioned in early 2014, and demonstrated beam circulation with energy recovery. In the cERL vacuum system, low-impedance vacuum components are required to circulate high-intensity, low-emittance and short-bunch electron beams. We therefore developed ultra-high-vacuum (UHV)-compatible flanges that can connect beam tubes seamlessly, and employed retractable beam monitors, namely, a movable Faraday cup and screen monitors. In most parts of the accelerator, pressures below 1×10{sup −7} Pa are required to mitigate beam-gasmore » interactions. Particularly, near the photocathode electron gun and the superconducting (SC) cavities, pressures below 1×10{sup −8} Pa are required. The beam tubes in the sections adjoining the SC cavities were coated with non-evaporable getter (NEG) materials, to reduce gas condensation on the cryo-surfaces. During the accelerator commissioning, stray magnetic fields from the permanent magnets of some cold cathode gauges (CCGs) were identified as a source of the disturbance to the beam orbit. Magnetic shielding was specially designed as a remedy for this issue.« less

Evaporation dynamics of completely wetting drops on geometrically textured surfaces

NASA Astrophysics Data System (ADS)

Mekhitarian, Loucine; Sobac, Benjamin; Dehaeck, Sam; Haut, Benoît; Colinet, Pierre

2017-10-01

This study deals with the evaporation dynamics of completely wetting and highly volatile drops deposited on geometrically textured but chemically homogeneous surfaces. The texturation consists in a cylindrical pillars array with a square pitch. The triple line dynamics and the drop shape are characterized by an interferometric method. A parametric study is realized by varying the radius and the height of the pillars (at fixed interpillar distance), allowing to distinguish three types of dynamics: i) an evaporation-dominated regime with a receding triple line; ii) a spreading-dominated regime with an initially advancing triple line; iii) a cross-over region with strong pinning effects. The overall picture is in qualitative agreement with a mathematical model showing that the selected regime mostly depends on the value of a dimensionless parameter comparing the time scales for evaporation and spreading into the substrate texture.

Method for sequentially processing a multi-level interconnect circuit in a vacuum chamber

NASA Technical Reports Server (NTRS)

Routh, D. E.; Sharma, G. C. (Inventor)

1984-01-01

An apparatus is disclosed which includes a vacuum system having a vacuum chamber in which wafers are processed on rotating turntables. The vacuum chamber is provided with an RF sputtering system and a dc magnetron sputtering system. A gas inlet introduces various gases to the vacuum chamber and creates various gas plasma during the sputtering steps. The rotating turntables insure that the respective wafers are present under the sputtering guns for an average amount of time such that consistency in sputtering and deposition is achieved. By continuous and sequential processing of the wafers in a common vacuum chamber without removal, the adverse affects of exposure to atmospheric conditions are eliminated providing higher quality circuit contacts and functional device.

Metals purification by improved vacuum arc remelting

DOEpatents

Zanner, Frank J.; Williamson, Rodney L.; Smith, Mark F.

1994-12-13

The invention relates to improved apparatuses and methods for remelting metal alloys in furnaces, particularly consumable electrode vacuum arc furnaces. Excited reactive gas is injected into a stationary furnace arc zone, thus accelerating the reduction reactions which purify the metal being melted. Additionally, a cooled condensation surface is disposed within the furnace to reduce the partial pressure of water in the furnace, which also fosters the reduction reactions which result in a purer produced ingot. Methods and means are provided for maintaining the stationary arc zone, thereby reducing the opportunity for contaminants evaporated from the arc zone to be reintroduced into the produced ingot.

Characterization of thermally evaporated lead iodide films aimed for the detection of X-rays

NASA Astrophysics Data System (ADS)

Caldeira Filho, A. M.; Mulato, M.

2011-04-01

Some semiconductor materials such as lead iodide (PbI2) have applications in the detection of ionizing radiation at room temperature using the direct detection method. In this work we investigate lead iodide films deposited by thermal evaporation. The morphology, structure, and electric properties were investigated as a function of deposition height, i.e. the distance between evaporation-boat and substrates. The results show a morphology of vertical leaves and X-ray diffraction shows just one preferential orientation along the direction 110. Energy dispersive spectroscopy reveals that the films are not stoichiometric, with excess iodine atoms. Electrical resistivity of about 108 Ω cm was measured. This is smaller than for the bulk due to structural defects. The values of activation energy for electric transport increase from 0.52 up to 1.1 eV with decreasing deposition height, what indicates that the best film is the one deposited at the shortest distance. Exposure under X-ray mammographic energy shows a linear behavior up to 500 mR. No variation in sensibility was observed between 22 and 30 kVp.

Pure Material Vapor Source by Induction Heating Evaporator for an Electron Cyclotron Resonance Ion Source

NASA Astrophysics Data System (ADS)

Matsui, Y.; Watanabe, T.; Satani, T.; Muramatsu, M.; Tanaka, K.; Kitagawa, A.; Yoshida, Y.; Sato, F.; Kato, Y.; Iida, T.

2008-11-01

Multiply charged iron ions are produced from solid pure material in an electron cyclotron resonance (ECR) ion source. We develop an evaporator by using induction heating with the induction coil which is made from bare molybdenum wire and surrounding the pure iron rod. We optimize the shape of induction heating coil and operation of rf power supply. We conduct experiment to investigate reproducibility and stability in the operation and heating efficiency. Induction heating evaporator produces pure material vapor, because materials directly heated by eddy currents have non-contact with insulated materials which are impurity gas sources. The power and the frequency of the induction currents range from 100 to 900 W and from 48 to 23 kHz, respectively. The working pressure is about 10-4 to 10-3 Pa. We measure temperature of iron rod and film deposition rate by depositing iron vapor to crystal oscillator. We confirm stability and reproducibility of evaporator enough to conduct experiment in ECR ion source. We can obtain required temperature of iron under maximum power of power supply. We are aiming the evaporator higher melting point material than iron.

Deriving properties of low-volatile substances from isothermal evaporation curves

NASA Astrophysics Data System (ADS)

Ralys, Ricardas V.; Uspenskiy, Alexander A.; Slobodov, Alexander A.

2016-01-01

Mass flux occurring when a substance evaporates from an open surface is proportional to its saturated vapor pressure at a given temperature. The proportionality coefficient that relates this flux to the vapor pressure shows how far a system is from equilibrium and is called the accommodation coefficient. Under vacuum, when a system deviates from equilibrium to the greatest extent possible, the accommodation coefficient equals unity. Under finite pressure, however, the accommodation coefficient is no longer equal to unity, and in fact, it is much less than unity. In this article, we consider the isothermal evaporation or sublimation of low-volatile individual substances under conditions of thermogravimetric analysis, when the external pressure of the purging gas is equal to the atmospheric pressure and the purging gas rate varies. When properly treated, the dependence of sample mass over time provides us with various information on the properties of the examined compound, such as saturated vapor pressure, diffusion coefficient, and density of the condensed (liquid or solid) phase at the temperature of experiment. We propose here the model describing the accommodation coefficient as a function of both substance properties and experimental conditions. This model gives the final expression for evaporation rate, and thus for mass dependence over time, with approximation parameters resulting in the properties being sought.

Evaporation of sessile droplets affected by graphite nanoparticles and binary base fluids.

PubMed

Zhong, Xin; Duan, Fei

2014-11-26

The effects of ethanol component and nanoparticle concentration on evaporation dynamics of graphite-water nanofluid droplets have been studied experimentally. The results show that the formed deposition patterns vary greatly with an increase in ethanol concentration from 0 to 50 vol %. Nanoparticles have been observed to be carried to the droplet surface and form a large piece of aggregate. The volume evaporation rate on average increases as the ethanol concentration increases from 0 to 50 vol % in the binary mixture nanofluid droplets. The evaporation rate at the initial stage is more rapid than that at the late stage to dry, revealing a deviation from a linear fitting line, standing for a constant evaporation rate. The deviation is more intense with a higher ethanol concentration. The ethanol-induced smaller liquid-vapor surface tension leads to higher wettability of the nanofluid droplets. The graphite nanoparticles in ethanol-water droplets reinforce the pinning effect in the drying process, and the droplets with more ethanol demonstrate the depinning behavior only at the late stage. The addition of graphite nanoparticles in water enhances a droplet baseline spreading at the beginning of evaporation, a pinning effect during evaporation, and the evaporation rate. However, with a relatively high nanoparticle concentration, the enhancement is attenuated.

Superconducting Vacuum-Gap Crossovers for High Performance Microwave Applications

NASA Technical Reports Server (NTRS)

Denis, Kevin L.; Brown, Ari D.; Chang, Meng-Ping; Hu, Ron; U-Yen, Kongpop; Wollack, Edward J.

2016-01-01

The design and fabrication of low-loss wide-bandwidth superconducting vacuum-gap crossovers for high performance millimeter wave applications are described. In order to reduce ohmic and parasitic losses at millimeter wavelengths a vacuum gap is preferred relative to dielectric spacer. Here, vacuum-gap crossovers were realized by using a sacrificial polymer layer followed by niobium sputter deposition optimized for coating coverage over an underlying niobium signal layer. Both coplanar waveguide and microstrip crossover topologies have been explored in detail. The resulting fabrication process is compatible with a bulk micro-machining process for realizing waveguide coupled detectors, which includes sacrificial wax bonding, and wafer backside deep reactive ion etching for creation of leg isolated silicon membrane structures. Release of the vacuum gap structures along with the wax bonded wafer after DRIE is implemented in the same process step used to complete the detector fabrication. ?

Removing lead from metallic mixture of waste printed circuit boards by vacuum distillation: factorial design and removal mechanism.

PubMed

Li, Xingang; Gao, Yujie; Ding, Hui

2013-10-01

The lead removal from the metallic mixture of waste printed circuit boards by vacuum distillation was optimized using experimental design, and a mathematical model was established to elucidate the removal mechanism. The variables studied in lead evaporation consisted of the chamber pressure, heating temperature, heating time, particle size and initial mass. The low-level chamber pressure was fixed at 0.1 Pa as the operation pressure. The application of two-level factorial design generated a first-order polynomial that agreed well with the data for evaporation efficiency of lead. The heating temperature and heating time exhibited significant effects on the efficiency, which was validated by means of the copper-lead mixture experiments. The optimized operating conditions within the region studied were the chamber pressure of 0.1 Pa, heating temperature of 1023 K and heating time of 120 min. After the conditions were employed to remove lead from the metallic mixture of waste printed circuit boards, the efficiency was 99.97%. The mechanism of the effects was elucidated by mathematical modeling that deals with evaporation, mass transfer and condensation, and can be applied to a wider range of metal removal by vacuum distillation. Copyright © 2013 Elsevier Ltd. All rights reserved.

High-performance perovskite CH3NH3PbI3 thin films for solar cells prepared by single-source physical vapour deposition

PubMed Central

Fan, Ping; Gu, Di; Liang, Guang-Xing; Luo, Jing-Ting; Chen, Ju-Long; Zheng, Zhuang-Hao; Zhang, Dong-Ping

2016-01-01

In this work, an alternative route to fabricating high-quality CH3NH3PbI3 thin films is proposed. Single-source physical vapour deposition (SSPVD) without a post-heat-treating process was used to prepare CH3NH3PbI3 thin films at room temperature. This new process enabled complete surface coverage and moisture stability in a non-vacuum solution. Moreover, the challenges of simultaneously controlling evaporation processes of the organic and inorganic sources via dual-source vapour evaporation and the heating process required to obtain high crystallization were avoided. Excellent composition with stoichiometry transferred from the powder material, a high level of tetragonal phase-purity, full surface coverage, well-defined grain structure, high crystallization and reproducibility were obtained. A PCE of approximately 10.90% was obtained with a device based on SSPVD CH3NH3PbI3. These initial results suggest that SSPVD is a promising method to significantly optimize perovskite CH3NH3PbI3 solar cell efficiency. PMID:27426686

Hollow Fiber Spacesuit Water Membrane Evaporator Development and Testing for Advanced Spacesuits

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Trevino, Luis; Tsioulos, Gus; Settles, Joseph; Colunga, Aaron; Vogel, Matthew; Vonau, Walt

2010-01-01

Grant Bue and Matthew Vogel presented the two types of Spacesuit Water Membrane Evaporators (SWME) that were developed based on hydrophobic microporous membranes. One type, the Sheet Membrane (SaM) SWME, is composed of six concentric Teflon sheet membranes fixed on cylindrical-supporting screens to form three concentric annular water channels. Those water channels are surrounded by vacuum passages to draw off the water vapor that passes through the membrane. The other type, the Hollow Fiber (HoFi) SWME, is composed of more than 14,000 tubes. Water flows through the tubes and water vapor passes through the tube wall to the shell side that vents to the vacuum of space. Both SWME types have undergone testing to baseline the performance at predicted operating temperatures and flow rates; the units also have been subjected to contamination testing and other conditions to test resiliency.

Fate of sulfur mustard on soil: Evaporation, degradation, and vapor emission.

PubMed

Jung, Hyunsook; Kah, Dongha; Chan Lim, Kyoung; Lee, Jin Young

2017-01-01

After application of sulfur mustard to the soil surface, its possible fate via evaporation, degradation following absorption, and vapor emission after decontamination was studied. We used a laboratory-sized wind tunnel, thermal desorber, gas chromatograph-mass spectrometry (GC-MS), and 13 C nuclear magnetic resonance ( 13 C NMR) for systematic analysis. When a drop of neat HD was deposited on the soil surface, it evaporated slowly while being absorbed immediately into the matrix. The initial evaporation or drying rates of the HD drop were found to be power-dependent on temperature and initial drop volume. Moreover, drops of neat HD, ranging in size from 1 to 6 μL, applied to soil, evaporated at different rates, with the smaller drops evaporating relatively quicker. HD absorbed into soil remained for a month, degrading eventually to nontoxic thiodiglycol via hydrolysis through the formation of sulfonium ions. Finally, a vapor emission test was performed for HD contaminant after a decontamination process, the results of which suggest potential risk from the release of trace chemical quantities of HD into the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool in laser evaporation methods

NASA Astrophysics Data System (ADS)

Callahan, John H.; Galicia, Marsha C.; Vertes, Akos

2002-09-01

Laser evaporation techniques, including matrix-assisted pulsed laser evaporation (MAPLE), are attracting increasing attention due to their ability to deposit thin layers of undegraded synthetic and biopolymers. Laser evaporation methods can be implemented in reflection geometry with the laser and the substrate positioned on the same side of the target. In some applications (e.g. direct write, DW), however, transmission geometry is used, i.e. the thin target is placed between the laser and the substrate. In this case, the laser pulse perforates the target and transfers some target material to the substrate. In order to optimize evaporation processes it is important to know the composition of the target plume and the material deposited from the plume. We used a recently introduced analytical method, atmospheric pressure matrix-assisted laser desorption ionization (AP-MALDI) to characterize the ionic components of the plume both in reflection and in transmission geometry. This technique can also be used to directly probe materials deposited on surfaces (such as glass slides) by laser evaporation methods. The test compound (small peptides, e.g. Angiotensin I, ATI or Substance P) was mixed with a MALDI matrix (α-cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA) or 2,5-dihydroxybenzoic acid (DHB)) and applied to the stainless steel (reflection geometry) or transparent conducting (transmission geometry) target holder. In addition to the classical dried droplet method, we also used electrospray target deposition to gain better control of crystallite size, thickness and homogeneity. The target was mounted in front of the inlet orifice of an ion trap mass spectrometer (IT-MS) that sampled the ionic components of the plume generated by a nitrogen laser. We studied the effect of several parameters, such as, the orifice to target distance, illumination geometry, extracting voltage distribution and sample preparation on the generated ions. Various analyte-matrix and

Adsorption calorimetry during metal vapor deposition on single crystal surfaces: Increased flux, reduced optical radiation, and real-time flux and reflectivity measurements

NASA Astrophysics Data System (ADS)

Sellers, Jason R. V.; James, Trevor E.; Hemmingson, Stephanie L.; Farmer, Jason A.; Campbell, Charles T.

2013-12-01

Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ˜18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

Adsorption calorimetry during metal vapor deposition on single crystal surfaces: increased flux, reduced optical radiation, and real-time flux and reflectivity measurements.

PubMed

Sellers, Jason R V; James, Trevor E; Hemmingson, Stephanie L; Farmer, Jason A; Campbell, Charles T

2013-12-01

Thin films of metals and other materials are often grown by physical vapor deposition. To understand such processes, it is desirable to measure the adsorption energy of the deposited species as the film grows, especially when grown on single crystal substrates where the structure of the adsorbed species, evolving interface, and thin film are more homogeneous and well-defined in structure. Our group previously described in this journal an adsorption calorimeter capable of such measurements on single-crystal surfaces under the clean conditions of ultrahigh vacuum [J. T. Stuckless, N. A. Frei, and C. T. Campbell, Rev. Sci. Instrum. 69, 2427 (1998)]. Here we describe several improvements to that original design that allow for heat measurements with ~18-fold smaller standard deviation, greater absolute accuracy in energy calibration, and, most importantly, measurements of the adsorption of lower vapor-pressure materials which would have previously been impossible. These improvements are accomplished by: (1) using an electron beam evaporator instead of a Knudsen cell to generate the metal vapor at the source of the pulsed atomic beam, (2) changing the atomic beam design to decrease the relative amount of optical radiation that accompanies evaporation, (3) adding an off-axis quartz crystal microbalance for real-time measurement of the flux of the atomic beam during calorimetry experiments, and (4) adding capabilities for in situ relative diffuse optical reflectivity determinations (necessary for heat signal calibration). These improvements are not limited to adsorption calorimetry during metal deposition, but also could be applied to better study film growth of other elements and even molecular adsorbates.

Method for sequentially processing a multi-level interconnect circuit in a vacuum chamber

NASA Technical Reports Server (NTRS)

Routh, D. E.; Sharma, G. C. (Inventor)

1982-01-01

The processing of wafer devices to form multilevel interconnects for microelectronic circuits is described. The method is directed to performing the sequential steps of etching the via, removing the photo resist pattern, back sputtering the entire wafer surface and depositing the next layer of interconnect material under common vacuum conditions without exposure to atmospheric conditions. Apparatus for performing the method includes a vacuum system having a vacuum chamber in which wafers are processed on rotating turntables. The vacuum chamber is provided with an RF sputtering system and a DC magnetron sputtering system. A gas inlet is provided in the chamber for the introduction of various gases to the vacuum chamber and the creation of various gas plasma during the sputtering steps.

Violations of the equivalence principle by a nonlocally reconstructed vacuum at the black hole horizon.

PubMed

Bousso, Raphael

2014-01-31

If information escapes from an evaporating black hole, then field modes just outside the horizon must be thermally entangled with distant Hawking radiation. But for an infalling observer to find empty space at the horizon, the same modes would have to be entangled with the black hole interior. Thus, unitarity appears to require a "firewall" at the horizon. Identifying the interior with the distant radiation promises to resolve the entanglement conflict and restore the vacuum. But the map must adjust for any interactions, or else the firewall will reappear if the Hawking radiation scatters off the cosmic microwave background. Such a map produces a "frozen vacuum," a phenomenon that is arguably worse than a firewall. An infalling observer is unable to excite the vacuum near the horizon. This allows the horizon to be locally detected and so violates the equivalence principle.

(abstract) Optical Scattering and Surface Microroughness of Ion Beam Deposited Au and Pt Thin Films

NASA Technical Reports Server (NTRS)

Al-Jumaily, Ghanim A.; Raouf, Nasrat A.; Edlou, Samad M.; Simons, John C.

1994-01-01

Thin films of gold and platinum have been deposited onto superpolished fused silica substrates using thermal evaporation, ion assisted deposition (IAD), and ion assisted sputtering. The influence of ion beam flux, thin film material, and deposition rate on the films microroughness have been investigated. Short range surface microroughness of the films has been examined using scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Long range surface microroughness has been characterized using an angle resolved optical scatterometer. Results indicate that ion beam deposited coatings have improved microstructure over thermally evaporated films.

Using deposition rate to increase the thermal and kinetic stability of vapor-deposited hole transport layer glasses via a simple sublimation apparatus

NASA Astrophysics Data System (ADS)

Kearns, Kenneth L.; Krzyskowski, Paige; Devereaux, Zachary

2017-05-01

Deposition rate is known to affect the relative stability of vapor-deposited glasses; slower rates give more stable materials due to enhanced mobility at the free surface of the film. Here we show that the deposition rate can affect both the thermodynamic and kinetic stabilities of N ,N' -bis(3-methylphenyl)-N ,N' -diphenylbenzidine (TPD) and N ,N' -di-[(1-naphthyl)-N ,N' -diphenyl]-1,1'-biphenyl)-4,4'-diamine (NPD) glasses used as hole transport layers for organic light emitting diodes (OLEDs). A simple, low-vacuum glass sublimation apparatus and a high vacuum deposition chamber were used to deposit the glass. 50 μm thick films were deposited in the sublimation apparatus and characterized by differential scanning calorimetry while 75 nm thick films were prepared in the high vacuum chamber and studied by hot-stage spectroscopic ellipsometry (SE). The thermodynamic stability from both preparation chambers was consistent and showed that the fictive temperature (Tfictive) was more than 30 K lower than the conventional glass transition temperature (Tg) at the slowest deposition rates. The kinetic stability, measured as the onset temperature (Tonset) where the glass begins to transform into the supercooled liquid, was 16-17 K greater than Tg at the slowest rates. Tonset was systematically lower for the thin films characterized by SE and was attributed to the thickness dependent transformation of the glass into the supercooled liquid. These results show the first calorimetric characterization of the stability of glasses for OLED applications made by vapor deposition and the first direct comparison of deposition apparatuses as a function of the deposition rate. The ease of fabrication will create an opportunity for others to study the effect of deposition conditions on glass stability.

Self-contained in-vacuum in situ thin film stress measurement tool

NASA Astrophysics Data System (ADS)

Reinink, J.; van de Kruijs, R. W. E.; Bijkerk, F.

2018-05-01

A fully self-contained in-vacuum device for measuring thin film stress in situ is presented. The stress was measured by measuring the curvature of a cantilever on which the thin film was deposited. For this, a dual beam laser deflectometer was used. All optics and electronics needed to perform the measurement are placed inside a vacuum-compatible vessel with the form factor of the substrate holders of the deposition system used. The stand-alone nature of the setup allows the vessel to be moved inside a deposition system independently of optical or electronic feedthroughs while measuring continuously. A Mo/Si multilayer structure was analyzed to evaluate the performance of the setup. A radius of curvature resolution of 270 km was achieved. This allows small details of the stress development to be resolved, such as the interlayer formation between the layers and the amorphous-to-crystalline transition of the molybdenum which occurs at around 2 nm. The setup communicates with an external computer via a Wi-Fi connection. This wireless connection allows remote control over the acquisition and the live feedback of the measured stress. In principle, the vessel can act as a general metrology platform and add measurement capabilities to deposition setups with no modification to the deposition system.

Material Outgassing, Identification and Deposition, MOLIDEP System

NASA Technical Reports Server (NTRS)

Scialdone, John J.; Montoya, Alex F.

2002-01-01

The outgassing tests are performed employing a modified vacuum operated Cahn analytical microbalance, identified as the MOLIDEP system. The test measures under high vacuum, the time varying Molecular mass loss of a material sample held at a chosen temperature; it Identifies the outgassing molecular components using an inline SRS 300 amu Residual Gas Analyzer (RGA) and employs a temperature controlled 10 MHz Quartz Crystal Microbalance (QCM) to measure the condensable DEPosits. Both the QCM and the RGA intercept within the conductive passage the outgassing products being evacuated by a turbomolecular pump. The continuous measurements of the mass loss, the rate of loss, the sample temperature, the rate of temperature change, the QCM temperature and the QCM recorded condensable deposits or rate of deposits are saved to an Excel spreadsheet. A separate computer controls the RGA.

Commissioning of the vacuum system of the KATRIN Main Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arenz, M.; Babutzka, M.; Bahr, M.

The KATRIN experiment will probe the neutrino mass by measuring the β-electron energy spectrum near the endpoint of tritium β-decay. We performed an integral energy analysis by an electro-static spectrometer (``Main Spectrometer''), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m 3, and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the β-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. Furthermore, a system consisting of 6 turbo-molecular pumps andmore » 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300 °C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10 -11 mbar range. We demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.« less

Commissioning of the vacuum system of the KATRIN Main Spectrometer

DOE PAGES

Arenz, M.; Babutzka, M.; Bahr, M.; ...

2016-04-07

The KATRIN experiment will probe the neutrino mass by measuring the β-electron energy spectrum near the endpoint of tritium β-decay. We performed an integral energy analysis by an electro-static spectrometer (``Main Spectrometer''), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m 3, and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the β-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. Furthermore, a system consisting of 6 turbo-molecular pumps andmore » 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300 °C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10 -11 mbar range. We demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.« less

Condensed milk storage and evaporation affect the flavor of nonfat dry milk.

PubMed

Park, Curtis W; Drake, MaryAnne

2016-12-01

Unit operations in nonfat dry milk (NFDM) manufacture influence sensory properties, and consequently, its use and acceptance in ingredient applications. Condensed skim milk may be stored at refrigeration temperatures for extended periods before spray drying due to shipping or lack of drying capacity. Currently, NFDM processors have 2 options for milk concentration up to 30% solids: evaporation (E) or reverse osmosis (RO). The objective of this study was to determine the effect of condensed milk storage and milk concentration method (E vs. RO) on the flavor of NFDM and investigate mechanisms behind flavor differences. For experiment 1, skim milk was pasteurized and concentrated to 30% solids by E or RO and then either stored for 24h at 4°C or concentrated to 50% solids by E and spray dried immediately. To investigate mechanisms behind the results from experiment 1, experiment 2 was constructed. In experiment 2, pasteurized skim milk was subjected to 1 of 4 treatments: control (no E), heated in the evaporator without vacuum, E concentration to 30% solids, or E concentration to 40% solids. The milks were then diluted to the same solids content and evaluated. Volatile compounds were also measured during concentration in the vapor separator of the evaporator. Sensory properties were evaluated by descriptive sensory analysis and instrumental volatile compound analysis was conducted to evaluate volatile compounds. Interaction effects between storage and method of concentration were investigated. In experiment 1, E decreased sweet aromatic flavor and many characteristic milk flavor compounds and increased cardboard and cooked flavors in NFDM compared with RO. Liquid storage increased cardboard flavor and hexanal and octanal and decreased sweet aromatic flavors and vanillin concentration. Results from experiment 2 indicated that the characteristic milk flavors and their associated volatile compounds were removed by the vapor separator in the evaporator due to the heat and

Transparent arrays of silver nanowire rings driven by evaporation of sessile droplets

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Kang, Giho; Seong, Baekhoon; Chae, Illkyeong; Teguh Yudistira, Hadi; Lee, Hyungdong; Kim, Hyunggun; Byun, Doyoung

2017-11-01

A coffee-ring pattern can be yielded on the three-phase contact line following evaporation of sessile droplets with suspended insoluble solutes, such as particles, DNA molecules, and mammalian cells. The formation of such coffee-ring, together with their suppression has been applied in printing and coating technologies. We present here an experimental study on the assembly of silver nanowires inside an evaporating droplet of a colloidal suspension. The effects of nanowire length and concentration on coffee-ring formation of the colloidal suspension were investigated. Several sizes of NWs with an aspect ratio between 50 and 1000 were systematically investigated to fabricate coffee-ring patterns. Larger droplets containing shorter nanowires formed clearer ring deposits after evaporation. An order-to-disorder transition of the nanowires’ alignment was found inside the rings. A printing technique with the evaporation process enabled fabrication of arrays of silver nanowire rings. We could manipulate the patterns silver nanowire rings, which might be applied to the transparent and flexible electrode.

IMPEDANCE MEASUREMENT OF VACUUM CHAMBER COMPONENTS FOR THE ADVANCE PHOTON SOURCE (APS) UPGRADE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sangroula, M.; Lindberg, R.; Lill, R.

2017-06-16

The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulationmore » results for other critical components using a novel Goubau line (G-line) set up.« less

Impedance measurement of vacuum chamber components for the Advance Photon Source(APS) Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sangroula, M.; Lindberg, R.; Lill, R.

2017-01-01

The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulationmore » results for other critical components using a novel Goubau line (G-line) set up.« less

Space Evaporator-Absorber-Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Stephan, Ryan; Hodgson, Ed; Izenson, Mike; Chen, Weibo

2012-01-01

A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA s Spacesuit Water Membrane Evaporator (SWME), and Creare s flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 m2 radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduces the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

Regulatory off-gas analysis from the evaporation of Hanford simulated waste spiked with organic compounds.

PubMed

Saito, Hiroshi H; Calloway, T Bond; Ferrara, Daro M; Choi, Alexander S; White, Thomas L; Gibson, Luther V; Burdette, Mark A

2004-10-01

After strontium/transuranics removal by precipitation followed by cesium/technetium removal by ion exchange, the remaining low-activity waste in the Hanford River Protection Project Waste Treatment Plant is to be concentrated by evaporation before being mixed with glass formers and vitrified. To provide a technical basis to permit the waste treatment facility, a relatively organic-rich Hanford Tank 241-AN-107 waste simulant was spiked with 14 target volatile, semi-volatile, and pesticide compounds and evaporated under vacuum in a bench-scale natural circulation evaporator fitted with an industrial stack off-gas sampler at the Savannah River National Laboratory. An evaporator material balance for the target organics was calculated by combining liquid stream mass and analytical data with off-gas emissions estimates obtained using U.S. Environmental Protection Agency (EPA) SW-846 Methods. Volatile and light semi-volatile organic compounds (<220 degrees C BP, >1 mm Hg vapor pressure) in the waste simulant were found to largely exit through the condenser vent, while heavier semi-volatiles and pesticides generally remain in the evaporator concentrate. An OLI Environmental Simulation Program (licensed by OLI Systems, Inc.) evaporator model successfully predicted operating conditions and the experimental distribution of the fed target organics exiting in the concentrate, condensate, and off-gas streams, with the exception of a few semi-volatile and pesticide compounds. Comparison with Henry's Law predictions suggests the OLI Environmental Simulation Program model is constrained by available literature data.

Solution-processed field-effect transistors based on dihexylquaterthiophene films with performances exceeding those of vacuum-sublimed films.

PubMed

Leydecker, Tim; Trong Duong, Duc; Salleo, Alberto; Orgiu, Emanuele; Samorì, Paolo

2014-12-10

Solution-processable oligothiophenes are model systems for charge transport and fabrication of organic field-effect transistors (OFET) . Herein we report a structure vs function relationship study focused on the electrical characteristics of solution-processed dihexylquaterthiophene (DH4T)-based OFET. We show that by combining the tailoring of all interfaces in the bottom-contact bottom-gate transistor, via chemisorption of ad hoc molecules on electrodes and dielectric, with suitable choice of the film preparation conditions (including solvent type, concentration, volume, and deposition method), it is possible to fabricate devices exhibiting field-effect mobilities exceeding those of vacuum-processed DH4T transistors. In particular, the evaporation rate of the solvent, the processing temperature, as well as the concentration of the semiconducting material were found to hold a paramount importance in driving the self-assembly toward the formation of highly ordered and low-dimensional supramolecular architectures, confirming the kinetically governed nature of the self-assembly process. Among the various architectures, hundreds-of-micrometers long and thin DH4T crystallites exhibited enhanced charge transport.

Vacuum-annealing induced enhancements in the transparent conducting properties of Mo  +  F doped ZnO thin films

NASA Astrophysics Data System (ADS)

Dineshbabu, N.; Ravichandran, K.

2017-09-01

The decisive aim of the present study is to enhance the transparent conducting properties of Mo  +  F co-doped ZnO films through annealing. In this work, Mo  +  F co-doped ZnO (MFZO) films were deposited on glass substrates at a deposition temperature of 350 °C using a home-made nebulizer spray pyrolysis technique and the prepared samples were annealed under air and vacuum atmosphere at 400 °C for 2 h. The structural, electrical, optical, surface morphological and elemental properties of as-deposited, air-annealed and vacuum-annealed samples were compared using various analytical techniques. The vacuum-annealed sample shows lowest resistivity of 1.364  ×  10-3 Ω cm and high transmittance of 90% in the visible region with high ohmic conducting nature. The optical bandgap of the sample was found to be increased to 3.36 eV after vacuum annealing treatment. The XRD patterns of the films confirmed the polycrystalline nature. The PL measurements show the defect levels of the deposited films. The FESEM and AFM studies show an increase in the grain size and roughness of the films, respectively, after vacuum-annealing treatment. The presence of the elements before and after annealing treatment was confirmed using XPS analysis.

Deposition dynamics of multi-solvent bioinks

NASA Astrophysics Data System (ADS)

Kaneelil, Paul; Pack, Min; Cui, Chunxiao; Han, Li-Hsin; Sun, Ying

2017-11-01

Inkjet printing cellular scaffolds using bioinks is gaining popularity due to the advancement of printing technology as well as the growing demands of regenerative medicine. Numerous studies have been conducted on printing scaffolds of biomimetic structures that support the cell production of human tissues. However, the underlying physics of the deposition dynamics of bioinks remains elusive. Of particular interest is the unclear deposition dynamics of multi-solvent bioinks, which is often used to tune the micro-architecture formation. Here we systematically studied the effects of jetting frequency, solvent properties, substrate wettability, and temperature on the three-dimensional deposition patterns of bioinks made of Methacrylated Gelatin and Carboxylated Gelatin. The microflows inside the inkjet-printed picolitre drops were visualized using fluorescence tracer particles to decipher the complex processes of multi-solvent evaporation and solute self-assembly. The evolution of droplet shape was observed using interferometry. With the integrated techniques, the interplay of solvent evaporation, biopolymer deposition, and multi-drop interactions were directly observed for various ink and substrate properties, and printing conditions. Such knowledge enables the design and fabrication of a variety of tissue engineering scaffolds for potential use in regenerative medicine.

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

PubMed

Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

2016-01-20

The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

Vacuum force

NASA Astrophysics Data System (ADS)

Han, Yongquan

2015-03-01

To study on vacuum force, we must clear what is vacuum, vacuum is a space do not have any air and also ray. There is not exist an absolute the vacuum of space. The vacuum of space is relative, so that the vacuum force is relative. There is a certain that vacuum vacuum space exists. In fact, the vacuum space is relative, if the two spaces compared to the existence of relative vacuum, there must exist a vacuum force, and the direction of the vacuum force point to the vacuum region. Any object rotates and radiates. Rotate bend radiate- centripetal, gravity produced, relative gravity; non gravity is the vacuum force. Gravity is centripetal, is a trend that the objects who attracted wants to Centripetal, or have been do Centripetal movement. Any object moves, so gravity makes the object curve movement, that is to say, the radiation range curve movement must be in the gravitational objects, gravity must be existed in non vacuum region, and make the object who is in the region of do curve movement (for example: The earth moves around the sun), or final attracted in the form gravitational objects, and keep relatively static with attract object. (for example: objects on the earth moves but can't reach the first cosmic speed).

Measurement of the accumulation of water ice on optical components in cryogenic vacuum environments

NASA Astrophysics Data System (ADS)

Moeller, Trevor M.; Montgomery Smith, L.; Collins, Frank G.; Labello, Jesse M.; Rogers, James P.; Lowry, Heard S.; Crider, Dustin H.

2012-11-01

Standard vacuum practices mitigate the presence of water vapor and contamination inside cryogenic vacuum chambers. However, anomalies can occur in the facility that can cause the accumulation of amorphous water ice on optics and test articles. Under certain conditions, the amorphous ice on optical components shatters, which leads to a reduction in signal or failure of the component. An experiment was performed to study and measure the deposition of water (H2O) ice on optical surfaces under high-vacuum cryogenic conditions. Water was introduced into a cryogenic vacuum chamber, via a hydrated molecular sieve zeolite, through an effusion cell and impinged upon a quartz-crystal microbalance (QCM) and first-surface gold-plated mirror. A laser and photodiode setup, external to the vacuum chamber, monitored the multiple-beam interference reflectance of the ice-mirror configuration while the QCM measured the mass deposition. Data indicates that water ice, under these conditions, accumulates as a thin film on optical surfaces to thicknesses over 45 microns and can be detected and measured by nonintrusive optical methods which are based upon multiple-beam interference phenomena. The QCM validated the interference measurements. This experiment established proof-of-concept for a miniature system for monitoring ice accumulation within the chamber.

Ionized cluster beam deposition

NASA Technical Reports Server (NTRS)

Kirkpatrick, A. R.

1983-01-01

Ionized Cluster Beam (ICB) deposition, a new technique originated by Takagi of Kyoto University in Japan, offers a number of unique capabilities for thin film metallization as well as for deposition of active semiconductor materials. ICB allows average energy per deposited atom to be controlled and involves impact kinetics which result in high diffusion energies of atoms on the growth surface. To a greater degree than in other techniques, ICB involves quantitative process parameters which can be utilized to strongly control the characteristics of films being deposited. In the ICB deposition process, material to be deposited is vaporized into a vacuum chamber from a confinement crucible at high temperature. Crucible nozzle configuration and operating temperature are such that emerging vapor undergoes supercondensation following adiabatic expansion through the nozzle.

Chemical-Vapor-Deposited Diamond Film

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa

1999-01-01

This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

XPS study of thermal and electron-induced decomposition of Ni and Co acetylacetonate thin films for metal deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, Theodor; Warneke, Jonas; Zielasek, Volkmar, E-mail: zielasek@uni-bremen.de

2016-07-15

Optimizing thin metal film deposition techniques from metal-organic precursors such as atomic layer deposition, chemical vapor deposition (CVD), or electron beam-induced deposition (EBID) with the help of surface science analysis tools in ultrahigh vacuum requires a contamination-free precursor delivery technique, especially in the case of the less volatile precursors. For this purpose, the preparation of layers of undecomposed Ni(acac){sub 2} and Co(acac){sub 2} was tried via pulsed spray evaporation of a liquid solution of the precursors in ethanol into a flow of nitrogen on a CVD reactor. Solvent-free layers of intact precursor molecules were obtained when the substrate was heldmore » at a temperature of 115 °C. A qualitative comparison of thermally initiated and electron-induced precursor decomposition and metal center reduction was carried out. All deposited films were analyzed with respect to chemical composition quasi in situ by x-ray photoelectron spectroscopy. Thermally initiated decomposition yielded higher metal-to-metal oxide ratios in the deposit than the electron-induced process for which ratios of 60:40 and 20:80 were achieved for Ni and Co, resp. Compared to continuous EBID processes, all deposits showed low levels of carbon impurities of ∼10 at. %. Therefore, postdeposition irradiation of metal acetylacetonate layers by a focused electron beam and subsequent removal of intact precursor by dissolution in ethanol or by heating is proposed as electron beam lithography technique on the laboratory scale for the production of the metal nanostructures.« less

Interaction between the effects of evaporation rate and amount of simulated rainfall on development of the free-living stages of Haemonchus contortus.

PubMed

O'Connor, Lauren J; Kahn, Lewis P; Walkden-Brown, Stephen W

2008-08-17

A factorial experiment (3 x 4 x 2 x 3) was conducted in programmable incubators to investigate interaction between the effects of rainfall amount, rainfall distribution and evaporation rate on development of Haemonchus contortus to L3. Sheep faeces containing H. contortus eggs were incubated on sterilised soil under variable temperatures typical of summer in the Northern Tablelands of NSW, Australia. Simulated rainfall was applied in 1 of 3 amounts (12, 24 or 32 mm) and 4 distributions (a single event on the day after deposition, or the same total amount split in 2, 3 or 4 equal events over 2, 3 or 4 days, respectively). Samples were incubated at either a Low or High rate of evaporation (Low: 2.1-3.4 mm/day and High: 3.8-6.1 mm/day), and faeces and soil were destructively sampled at 4, 7 and 14 days post-deposition. Recovery of L3 from the soil (extra-pellet L3) increased over time (up to 0.52% at day 14) and with each increment of rainfall (12 mm: <0.01%; 24 mm: 0.10%; 32 mm: 0.45%) but was reduced under the High evaporation rate (0.01%) compared with the Low evaporation rate (0.31%). All rainfall amounts yielded significantly different recoveries of L3 under Low evaporation rates but there was no difference between the 12 and 24 mm treatments under the High evaporation rate. The distribution of simulated rainfall did not significantly affect recovery of infective larvae. Faecal moisture content was positively associated with L3 recovery, as was the ratio of cumulative precipitation and cumulative evaporation (P/E), particularly when measured in the first 4 days post-deposition. The results show that evaporation rate plays a significant role in regulating the influence of rainfall amount on the success of L3 transmission.

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

DTIC Science & Technology

2016-04-27

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials PI Maria received support to construct a physical...vapor deposition (PVD) system that combines electron beam (e- beam) evaporation, magnetron sputtering, pulsed laser ablation, and ion-assisted deposition ...The instrumentation enables clean, uniform, and rapid deposition of a wide variety of metallic, semiconducting, and ceramic thin films with

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erck, R.A.

A blue-green glow was observed in the cold-plate section of a conventional cryogenic pump used in a vacuum-deposition chamber. The fluorescence is associated with operation of an electron-beam evaporator and is present at all gas pressures and evaporator voltages used, but cannot be made to occur during operation of a 1 kV Kaufman-type ion source or a 3 kV electron source.

Stokes flow inside an evaporating liquid line for any contact angle

NASA Astrophysics Data System (ADS)

Petsi, A. J.; Burganos, V. N.

2008-09-01

Evaporation of droplets or liquid films lying on a substrate induces internal viscous flow, which affects the transport of suspended particles and, thus, the final deposit profile in numerous applications. In this work, the problem of Stokes flow inside a two-dimensional droplet, representing the cross section of an evaporating liquid line lying on a flat surface, is considered. The stream function formulation is adopted, leading to the biharmonic equation in bipolar coordinates. A solution in closed form is obtained for any contact angle in (0,π) and is, thus, valid for both hydrophilic and hydrophobic substrates. The solution can be used with any type of evaporation mechanism, including diffusion, convection, or kinetically controlled modes. Both pinned and depinned contact lines are considered. For the boundary conditions to be compatible at the contact lines, the Navier slip boundary condition is applied on the substrate. Numerical results are presented for kinetically and diffusion controlled evaporation. For pinned contact lines, the flow inside the evaporating liquid line is directed towards the edges, thus, promoting the coffee stain phenomenon. In the case of depinned contact lines and contact angle less than π/2 , the flow is directed towards the center of the droplet, whereas, for strongly hydrophobic substrates it is directed outwards.

Solar Cells for Lunar Application

NASA Technical Reports Server (NTRS)

Freundlich, Alex; Ignatiev, Alex

1997-01-01

In this work a preliminary study of the vacuum evaporation of silicon extracted from the lunar regolith has been undertaken. An electron gun vacuum evaporation system has been adapted for this purpose. Following the calibration of the system using ultra high purity silicon deposited on Al coated glass substrates, thin films of lunar Si were evaporated on a variety of crystalline substrates as well as on glass and lightweight 1 mil (25 microns) Al foil. Extremely smooth and featureless films with essentially semiconducting properties were obtained. Optical absorption analysis sets the bandgap (about 1.1 eV) and the refractive index (n=3.5) of the deposited thin films close to that of crystalline silicon. Secondary ion mass spectroscopy and energy dispersive spectroscopy analysis indicated that these films are essentially comparable to high purity silicon and that the evaporation process resulted in a substantial reduction of impurity levels. All layers exhibited a p-type conductivity suggesting the presence of a p-type dopant in the fabricated layers. While the purity of the 'lunar waste material' is below that of the 'microelectronic-grade silicon', the vacuum evaporated material properties seems to be adequate for the fabrication of average performance Si-based devices such as thin film solar cells. Taking into account solar cell thickness requirements (greater than 10 microns) and the small quantities of lunar material available for this study, solar cell fabrication was not possible. However, the high quality of the optical and electronic properties of evaporated thin films was found to be similar to those obtained using ultra-high purity silicon suggest that thin film solar cell production on the lunar surface with in situ resource utilization may be a viable approach for electric power generation on the moon.

Expressions for the evaporation of sessile liquid droplets incorporating the evaporative cooling effect.

PubMed

Wang, Yilin; Ma, Liran; Xu, Xuefeng; Luo, Jianbin

2016-12-15

The evaporation along the surface of pinned, sessile droplets is investigated numerically by using the combined field approach. In the present model, the evaporative cooling at the droplet surface which leads to a reduction in the evaporation is taken into account. Simple, yet accurate analytical expressions for the local evaporation flux and for the total evaporation rate of sessile droplets are obtained. The theoretical analyses indicate that the reduction in the evaporation becomes more pronounced as the evaporative cooling number Ec increases. The results also reveal that the variation of total evaporation rate with contact angle will change its trend as the intensity of the evaporative cooling changes. For small values of Ec, the total evaporation rate increases with the contact angle, the same as predicted by Deegan et al. and by Hu and Larson in their isothermal models in which the evaporative cooling is neglected. Contrarily, when the evaporative cooling effect is strong enough, the total evaporation rate will decrease as the contact angle increases. The present theory is corroborated experimentally, and found in good agreement with the expressions proposed by Hu and Larson in the limiting isothermal case. Copyright © 2016 Elsevier Inc. All rights reserved.

Alternative mechanism for coffee-ring deposition based on active role of free surface

NASA Astrophysics Data System (ADS)

Jafari Kang, Saeed; Vandadi, Vahid; Felske, James D.; Masoud, Hassan

2016-12-01

When a colloidal sessile droplet dries on a substrate, the particles suspended in it usually deposit in a ringlike pattern. This phenomenon is commonly referred to as the "coffee-ring" effect. One paradigm for why this occurs is as a consequence of the solutes being transported towards the pinned contact line by the flow inside the drop, which is induced by surface evaporation. From this perspective, the role of the liquid-gas interface in shaping the deposition pattern is somewhat minimized. Here, we propose an alternative mechanism for the coffee-ring deposition. It is based on the bulk flow within the drop transporting particles to the interface where they are captured by the receding free surface and subsequently transported along the interface until they are deposited near the contact line. That the interface captures the solutes as the evaporation proceeds is supported by a Lagrangian tracing of particles advected by the flow field within the droplet. We model the interfacial adsorption and transport of particles as a one-dimensional advection-generation process in toroidal coordinates and show that the theory reproduces ring-shaped depositions. Using this model, deposition patterns on both hydrophilic and hydrophobic surfaces are examined in which the evaporation is modeled as being either diffusive or uniform over the surface.

Friction and Wear of Ion-Beam-Deposited Diamondlike Carbon on Chemical-Vapor-Deposited, Fine-Grain Diamond

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Wu, Richard L. C.; Lanter, William C.

1996-01-01

Friction and wear behavior of ion-beam-deposited diamondlike carbon (DLC) films coated on chemical-vapor-deposited (CVD), fine-grain diamond coatings were examined in ultrahigh vacuum, dry nitrogen, and humid air environments. The DLC films were produced by the direct impact of an ion beam (composed of a 3:17 mixture of Ar and CH4) at ion energies of 1500 and 700 eV and an RF power of 99 W. Sliding friction experiments were conducted with hemispherical CVD diamond pins sliding on four different carbon-base coating systems: DLC films on CVD diamond; DLC films on silicon; as-deposited, fine-grain CVD diamond; and carbon-ion-implanted, fine-grain CVD diamond on silicon. Results indicate that in ultrahigh vacuum the ion-beam-deposited DLC films on fine-grain CVD diamond (similar to the ion-implanted CVD diamond) greatly decrease both the friction and wear of fine-grain CVD diamond films and provide solid lubrication. In dry nitrogen and in humid air, ion-beam-deposited DLC films on fine-grain CVD diamond films also had a low steady-state coefficient of friction and a low wear rate. These tribological performance benefits, coupled with a wider range of coating thicknesses, led to longer endurance life and improved wear resistance for the DLC deposited on fine-grain CVD diamond in comparison to the ion-implanted diamond films. Thus, DLC deposited on fine-grain CVD diamond films can be an effective wear-resistant, lubricating coating regardless of environment.

Battery-powered thin film deposition process for coating telescope mirrors in space

NASA Astrophysics Data System (ADS)

Sheikh, David A.

2016-07-01

Aluminum films manufactured in the vacuum of space may increase the broadband reflectance response of a space telescope operating in the EUV (50-nm to 115-nm) by eliminating absorbing metal-fluorides and metal-oxides, which significantly reduce aluminum's reflectance below 115-nm. Recent developments in battery technology allow small lithium batteries to rapidly discharge large amounts of energy. It is therefore conceivable to power an array of resistive evaporation filaments in a space environment, using a reasonable mass of batteries and other hardware. This paper presents modeling results for coating thickness as a function of position, for aluminum films made with a hexagonal array of battery powered evaporation sources. The model is based on measured data from a single battery-powered evaporation source.

Tensile and fatigue behaviors of printed Ag thin films on flexible substrates

NASA Astrophysics Data System (ADS)

Sim, Gi-Dong; Won, Sejeong; Lee, Soon-Bok

2012-11-01

Flexible electronics using nanoparticle (NP) printing has been highlighted as a key technology enabling eco-friendly, low-cost, and large-area fabrication. For NP-based printing to be used as a successive alternative to photolithography and vacuum deposition, stretchability and long term reliability must be considered. This paper reports the stretchability and fatigue behavior of 100 nm thick NP-based silver thin films printed on polyethylene-terephthalate substrate and compares it to films deposited by electron-beam evaporation. NP-based films show stretchability and fatigue life comparable to evaporated films with intergranular fracture as the dominant failure mechanism.

Investigations Of A Pulsed Cathodic Vacuum Arc

NASA Astrophysics Data System (ADS)

Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

2003-06-01

Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

Residual stress in obliquely deposited MgF2 thin films.

PubMed

Jaing, Cheng-Chung; Liu, Ming-Chung; Lee, Cheng-Chung; Cho, Wen-Hao; Shen, Wei-Ting; Tang, Chien-Jen; Liao, Bo-Huei

2008-05-01

MgF(2) films with a columnar microstructure are obliquely deposited on glass substrates by resistive heating evaporation. The columnar angles of the films increases with the deposition angle. Anisotropic stress does not develop in the films with tilted columns. The residual stresses in the films depend on the deposition and columnar angles in a columnar microstructure.

Evaporation Rate Study and NDMA Formation from UDMH/NO2 Reaction Products

NASA Technical Reports Server (NTRS)

Buchanan, Vanessa D.; Dee, Louis A.; Baker, David L.

2003-01-01

Laboratory samples of uns-dimethylhydrazine (UDMH) fuel/oxidizer (nitrogen dioxide) non-combustion reaction products (UFORP) were prepared using a unique permeation tube technology. Also, a synthetic UFORP was prepared from UDMH, N-nitrosodimethylamine (NDMA), dimethylammonium nitrate, sodium nitrite and purified water. The evaporation rate of UFORP and synthetic UFORP was determined under space vacuum (approx 10(exp -3) Torr) at -40 ?C and 0 ?C. The material remaining was analyzed and showed that the UFORP weight and NDMA concentration decreased over time; however, NDMA had not completely evaporated. Over 85% of the weight was removed by subjecting the UFORP to 10(-3) Torr for 7 hours at -40 ?C and 4 hours at 0 ?C. A mixture of dimethylammonium nitrate and sodium nitrite formed NDMA at a rapid rate in a moist air environment. A sample of UFORP residue was analyzed for formation of NDMA under various conditions. It was found that NDMA was not formed unless nitrite was added.

Performance of a Multifunctional Space Evaporator- Absorber-Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Bue, Grant; Quinn, Gregory

2013-01-01

The Space Evaporator-Absorber-Radiator (SEAR) is a nonventing thermal control subsystem that combines a Space Water Membrane Evaporator (SWME) with a Lithium Chloride Absorber Radiator (LCAR). The LCAR is a heat pump radiator that absorbs water vapor produced in the SWME. Because of the very low water vapor pressure at equilibrium with lithium chloride solution, the LCAR can absorb water vapor at a temperature considerably higher than the SWME, enabling heat rejection by thermal radiation from a relatively small area radiator. Prior SEAR prototypes used a flexible LCAR that was designed to be installed on the outer surface of a portable life support system (PLSS) backpack. This paper describes a SEAR subsystem that incorporates a very compact LCAR. The compact, multifunctional LCAR is built in the form of thin panels that can also serve as the PLSS structural shell. We designed and assembled a 2 sq ft prototype LCAR based on this design and measured its performance in thermal vacuum tests when supplied with water vapor by a SWME. These tests validated our models for SEAR performance and showed that there is enough area available on the PLSS backpack shell to enable heat rejection from the LCAR.

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials

DTIC Science & Technology

2016-04-27

Hybrid Physical Vapor Deposition Instrument for Advanced Functional Multilayers and Materials PI Maria received support to construct a physical... vapor deposition (PVD) system that combines electron beam (e- beam) evaporation, magnetron sputtering, pulsed laser ablation, and ion-assisted deposition ...peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Final Report: Hybrid Physical Vapor Deposition Instrument for Advanced

Preparation and investigation of diamond-like carbon stripper foils by filtered cathodic vacuum arc

NASA Astrophysics Data System (ADS)

Fan, Qiwen; Du, Yinghui; Zhang, Rong; Xu, Guoji

2013-04-01

Thin diamond-like carbon (DLC) stripper foils ˜5 μg/cm2 in thickness were produced and evaluated as heavy-ion strippers for the Beijing HI-13 Tandem Accelerator. The DLC layers ˜4 μg/cm2 in thickness were produced by the filtered cathodic vacuum arc technology onto glass slides coated with betaine-saccharose as releasing agent, which were previously covered with evaporated carbon layers ˜1 μg/cm2 in thickness by the controlled ac arc-discharge method. Irradiation lifetimes of the DLC stripper foils were tested using the heavy-ion beams at the terminal of the Beijing HI-13 Tandem Accelerator, and compared with those of the standard carbon stripper foils made by the combined dc and ac arc-discharge method. The measurements indicate that the DLC stripper foils outlast the standard combined dc and ac arc-discharge carbon stripper foils by a factor of at least 13 and 4for the 197Au- (˜9 MeV, ˜1 μA) and 63Cu- (˜9 MeV, ˜1 μA) ion beams, respectively. The structure and properties of the DLC foils deposited onto silicon substrates by the filtered cathodic vacuum arc technology were also evaluated and analyzed by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy images show that the DLC foils contain hardly droplets through the double 90° filters. The X-ray photoelectron spectrum indicates that sp3 bonds of the DLC foils exceed 70%. The integral intensity ratio of the D peak to the G peak (ID/IG) measured by the Raman spectroscopy is0.78.

Electronic structure of a laterally graded ZrO2-TiO2 film on Si(100) prepared by metal-organic chemical vapor deposition in ultrahigh vacuum

NASA Astrophysics Data System (ADS)

Richter, J. H.; Karlsson, P. G.; Sandell, A.

2008-05-01

A TiO2-ZrO2 film with laterally graded stoichiometry has been prepared by metal-organic chemical vapor deposition in ultrahigh vacuum. The film was characterized in situ using synchrotron radiation photoelectron spectroscopy (PES) and x-ray absorption spectroscopy. PES depth profiling clearly shows that Ti ions segregate toward the surface region when mixed with ZrO2. The binding energy of the ZrO2 electronic levels is constant with respect to the local vacuum level. The binding energy of the TiO2 electronic levels is aligned to the Fermi level down to a Ti /Zr ratio of about 0.5. At a Ti /Zr ratio between 0.1 and 0.5, the TiO2 related electronic levels become aligned to the local vacuum level. The addition of small amounts of TiO2 to ZrO2 results in a ZrO2 band alignment relative to the Fermi level that is less asymmetric than for pure ZrO2. The band edge positions shift by -0.6eV for a Ti /Zr ratio of 0.03. This is explained in terms of an increase in the work function when adding TiO2, an effect that becomes emphasized by Ti surface segregation.

Vacuum vapor deposition: A spinoff of space welding development

NASA Technical Reports Server (NTRS)

Poorman, R. M.

1991-01-01

A vapor deposition process has been defined through a spinoff effort of space welding development. In this development for welding in a space environment, a hollow electrode was used to add gas precisely at the welding arc. This provides gas for ionization which carries the welding arc current. During this welding development metal vapor coatings were observed. These coatings are unique in that they are produced by a new process. Some coatings produced and the potential of this new and innovative vapor deposition process are characterized. Advantages over prior art are discussed.

Layered tin monoselenide as advanced photothermal conversion materials for efficient solar energy-driven water evaporation.

PubMed

Yao, Jiandong; Zheng, Zhaoqiang; Yang, Guowei

2018-02-08

Solar energy-driven water evaporation lays a solid foundation for important photothermal applications such as sterilization, seawater desalination, and electricity generation. Due to the strong light-matter coupling, broad absorption wavelength range, and prominent quantum confinement effect, layered tin monoselenide (SnSe) holds a great potential to effectively harness solar irradiation and convert it to heat energy. In this study, SnSe is successfully deposited on a centimeter-scale nickel foam using a facile one-step pulsed-laser deposition approach. Importantly, the maximum evaporation rate of SnSe-coated nickel foam (SnSe@NF) reaches 0.85 kg m -2 h -1 , which is even 21% larger than that obtained with the commercial super blue coating (0.7 kg m -2 h -1 ) under the same condition. A systematic analysis reveals that its good photothermal conversion capability is attributed to the synergetic effect of multi-scattering-induced light trapping and the optimal trade-off between light absorption and phonon emission. Finally, the SnSe@NF device is further used for seawater evaporation, demonstrating a comparable evaporation rate (0.8 kg m -2 h -1 ) to that of fresh water and good stability over many cycles of usage. In summary, the current contribution depicts a facile one-step scenario for the economical and efficient solar-enabled SnSe@NF evaporation devices. More importantly, an in-depth analysis of the photothermal conversion mechanism underneath the layered materials depicts a fundamental paradigm for the design and application of photothermal devices based on them in the future.

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

DOE PAGES

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.; ...

2018-02-09

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Modeling solvent evaporation during thin film formation in phase separating polymer mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cummings, John; Lowengrub, John S.; Sumpter, Bobby G.

Preparation of thin films by dissolving polymers in a common solvent followed by evaporation of the solvent has become a routine processing procedure. However, modeling of thin film formation in an evaporating solvent has been challenging due to a need to simulate processes at multiple length and time scales. In this paper, we present a methodology based on the principles of linear non-equilibrium thermodynamics, which allows systematic study of various effects such as the changes in the solvent properties due to phase transformation from liquid to vapor and polymer thermodynamics resulting from such solvent transformations. The methodology allows for themore » derivation of evaporative flux and boundary conditions near each surface for simulations of systems close to the equilibrium. We apply it to study thin film microstructural evolution in phase segregating polymer blends dissolved in a common volatile solvent and deposited on a planar substrate. Finally, effects of the evaporation rates, interactions of the polymers with the underlying substrate and concentration dependent mobilities on the kinetics of thin film formation are studied.« less

Chemical changes exhibited by latent fingerprints after exposure to vacuum conditions.

PubMed

Bright, Nicholas J; Willson, Terry R; Driscoll, Daniel J; Reddy, Subrayal M; Webb, Roger P; Bleay, Stephen; Ward, Neil I; Kirkby, Karen J; Bailey, Melanie J

2013-07-10

The effect of vacuum exposure on latent fingerprint chemistry has been evaluated. Fingerprints were analysed using a quartz crystal microbalance to measure changes in mass, gas chromatography mass spectrometry to measure changes in lipid composition and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine changes in the content of water, fatty acids and their esters after exposure to vacuum. The results are compared with samples aged under ambient conditions. It was found that fingerprints lose around 26% of their mass when exposed to vacuum conditions, equivalent to around 5 weeks ageing under ambient conditions. Further exposure to vacuum causes a significant reduction in the lipid composition of a fingerprint, in particular with the loss of tetradecanoic and pentadecanoic acid, that was not observed in ambient aged samples. There are therefore implications for sequence in which fingerprint development procedures (for example vacuum metal deposition) are carried out, as well as the use of vacuum based methods such as secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption ionisation (MALDI) in the study of fingerprint chemistry. Copyright © 2013. Published by Elsevier Ireland Ltd.

MAPLE deposition of nanomaterials

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Arima, V.; Catalano, M.; Cesaria, M.; Cozzoli, P. D.; Martino, M.; Taurino, A.; Rella, R.; Scarfiello, R.; Tunno, T.; Zacheo, A.

2014-05-01

The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

2,3-Butanediol recovery from fermentation broth by alcohol precipitation and vacuum distillation.

PubMed

Jeon, Sangjun; Kim, Duk-Ki; Song, Hyohak; Lee, Hee Jong; Park, Sunghoon; Seung, Doyoung; Chang, Yong Keun

2014-04-01

This study presents a new and effective downstream process to recover 2,3-butanediol (2,3-BD) from fermentation broth which is produced by a recombinant Klebsiella pneumoniae strain. The ldhA-deficient K. pneumoniae strain yielded about 90 g/L of 2,3-BD, along with a number of by-products, such as organic acids and alcohols, in a 65 h fed-batch fermentation. The pH-adjusted cell-free fermentation broth was firstly concentrated until 2,3-BD reached around 500 g/L by vacuum evaporation at 50°C and 50 mbar vacuum pressure. The concentrated solution was further treated using light alcohols, including methanol, ethanol, and isopropanol, for the precipitation of organic acids and inorganic salts. Isopropanol showed the highest removal efficiency, in which 92.5% and 99.8% of organic acids and inorganic salts were precipitated, respectively. At a final step, a vacuum distillation process enabled the recovery of 76.2% of the treated 2,3-BD, with 96.1% purity, indicating that fermentatively produced 2,3-BD is effectively recovered by a simple alcohol precipitation and vacuum distillation. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Preventing Clogging In A Vacuum Plasma Spray Gun

NASA Technical Reports Server (NTRS)

Krotz, Phillip D.; Daniel, Ronald L., Jr.; Davis, William M.

1994-01-01

Modification of powder-injection ports enables lengthy, high-temperature deposition operations. Graphite inserts prevent clogging of ports through which copper powder injected into vacuum plasma spray (VPS) gun. Graphite liners eliminate need to spend production time refurbishing VPS gun, reducing cost of production and increasing productivity. Concept also applied to other material systems used for net-shape fabrication via VPS.

Broadband reflectance coatings for vacuum ultraviolet application

NASA Technical Reports Server (NTRS)

Herzig, Howard; Fleetwood, C. M., Jr.; Flint, B. K.

1987-01-01

An experimental investigation has obtained results indicating that neither LaF3 nor LiYF4 are acceptable alternatives to MgF2 as coatings for vacuum-deposited aluminum mirrors from which high UV reflectance down to 1150 A is required. Nevertheless, LaF3 may prove useful in those specialized applications in which the suppression of lower wavelength emissions, such as the 1216-A hydrogen line, is desirable.

Multifunctional Space Evaporator-Absorber-Radiator (SEAR)

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Hodgson, Ed; Izenson, Mike; Chen, Weibo

2013-01-01

A system for non-venting thermal control for spacesuits was built by integrating two previously developed technologies, namely NASA's Spacesuit Water Membrane Evaporator (SWME), and Creare's flexible version of the Lithium Chloride Absorber Radiator (LCAR). This SEAR system was tested in relevant thermal vacuum conditions. These tests show that a 1 sq m radiator having about three times as much absorption media as in the test article would be required to support a 7 hour spacewalk. The serial flow arrangement of the LCAR of the flexible version proved to be inefficient for venting non-condensable gas (NCG). A different LCAR packaging arrangement was conceived wherein the Portable Life Support System (PLSS) housing would be made with a high-strength carbon fiber composite honeycomb, the cells of which would be filled with the chemical absorption media. This new packaging reduce the mass and volume impact of the SEAR on the Portable Life Support System (PLSS) compared to the flexible design. A 0.2 sq m panel with flight-like honeycomb geometry is being constructed and will be tested in thermal and thermal vacuum conditions. Design analyses forecast improved system performance and improved NCG control. A flight-like regeneration system also is also being built and tested. Design analyses for the structurally integrated prototype as well as the earlier test data show that SEAR is not only practical for spacesuits but also has useful applications in spacecraft thermal control.

ASTM E 1559 method for measuring material outgassing/deposition kinetics has applications to aerospace, electronics, and semiconductor industries

NASA Technical Reports Server (NTRS)

Garrett, J. W.; Glassford, A. P. M.; Steakley, J. M.

1994-01-01

The American Society for Testing and Materials has published a new standard test method for characterizing time and temperature-dependence of material outgassing kinetics and the deposition kinetics of outgassed species on surfaces at various temperatures. This new ASTM standard, E 1559(1), uses the quartz crystal microbalance (QCM) collection measurement approach. The test method was originally developed under a program sponsored by the United States Air Force Materials Laboratory (AFML) to create a standard test method for obtaining outgassing and deposition kinetics data for spacecraft materials. Standardization by ASTM recognizes that the method has applications beyond aerospace. In particular, the method will provide data of use to the electronics, semiconductor, and high vacuum industries. In ASTM E 1559 the material sample is held in vacuum in a temperature-controlled effusion cell, while its outgassing flux impinges on several QCM's which view the orifice of the effusion cell. Sample isothermal total mass loss (TML) is measured as a function of time from the mass collected on one of the QCM's which is cooled by liquid nitrogen, and the view factor from this QCM to the cell. The amount of outgassed volatile condensable material (VCM) on surfaces at higher temperatures is measured as a function of time during the isothermal outgassing test by controlling the temperatures of the remaining QCM's to selected values. The VCM on surfaces at temperatures in between those of the collector QCM's is determined at the end of the isothermal test by heating the QCM's at a controlled rate and measuring the mass loss from the end of the QCM's as a function of time and temperature. This reevaporation of the deposit collected on the QCM's is referred to as QCM thermogravimetric analysis. Isothermal outgassing and deposition rates can be determined by differentiating the isothermal TML and VCM data, respectively, while the evaporation rates of the species can be obtained as a

Impact of droplet evaporation rate on resulting in vitro performance parameters of pressurized metered dose inhalers.

PubMed

Sheth, Poonam; Grimes, Matthew R; Stein, Stephen W; Myrdal, Paul B

2017-08-07

Pressurized metered dose inhalers (pMDIs) are widely used for the treatment of pulmonary diseases. The overall efficiency of pMDI drug delivery may be defined by in vitro parameters such as the amount of drug that deposits on the model throat and the proportion of the emitted dose that has particles that are sufficiently small to deposit in the lung (i.e., fine particle fraction, FPF). The study presented examines product performance of ten solution pMDI formulations containing a variety of cosolvents with diverse chemical characteristics by cascade impaction with three inlets (USP induction port, Alberta Idealized Throat, and a large volume chamber). Through the data generated in support of this study, it was demonstrated that throat deposition, cascade impactor deposition, FPF, and mass median aerodynamic diameter of solution pMDIs depend on the concentration and vapor pressure of the cosolvent, and the selection of model throat. Theoretical droplet lifetimes were calculated for each formulation using a discrete two-stage evaporation process model and it was determined that the droplet lifetime is highly correlated to throat deposition and FPF indicating that evaporation kinetics significantly influences pMDI drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Testing of Commercial Hollow Fiber Membranes for Space Suit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Trevino, Luis; Tsioulos, Gus; Hanford, Anthony

2009-01-01

Three commercial-off-the-shelf (COTS) hollow fiber (HoFi) membrane evaporators, modified for low pressure, were tested in a vacuum chamber at pressures below 33 pascals as potential space suit water membrane evaporator (SWME) heat rejection technologies. Water quality was controlled in a series of 25 tests, first simulating potable water reclaimed from waste water and then changing periodically to simulate the ever concentrating make-up of the circulating coolant over that is predicted over the course of 100 EVAs. Two of the systems, comprised of non-porous tubes with hydrophilic molecular channels as the water vapor transport mechanism, were severely impacted by the increasing concentrations of cations in the water. One of the systems, based on hydrophobic porous polypropylene tubes was not affected by the degrading water quality, or the presence of microbes. The polypropylene system, called SWME 1, was selected for further testing. An inverse flow configuration was also tested with SWME 1, with vacuum exposure on the inside of the tubes, provided only 20% of the performance of the standard configuration. SWME 1 was also modified to block 50% and 90% of the central tube layers, and tested to investigate performance efficiency. Performance curves were also developed in back-pressure regulation tests, and revealed important design considerations arising from the fully closed valve. SWME 1 was shown to be insensitive to air bubbles injected into the coolant loop. Development and testing of a full-scale prototype based on this technology and these test results is in progress.

Introduction of pinning centers into Sm1+xBa2Cu3+YO7-d coated conductor by reactive co-evaporation method

NASA Astrophysics Data System (ADS)

Kim, Gwan-Tae; Kim, Ho-Sup; Ha, Dong-Woo; Chung, Kook-Chae; Shinde, Kiran

2018-02-01

Sm1+xBa2Cu3+yO7-d (SmBCO)-coated conductors containing pinning centers were prepared by a reactive co-evaporation method using the EDDC (Evaporation using Drum in Dual Chamber) deposition system. Superconducting materials based on Sm, Ba, and Cu were evaporated in the evaporation chamber and deposited onto the drum-mounted substrate, while the deposited element reacted with oxygen and resulting in the SmBCO superconducting phase inside the reaction chamber. Tape-type samples (length = 30 cm, width = 4 mm, thickness = 0.1 mm) with the structure of Ag/SmBCO/LMO/MgO/Y2O3/Al2O3/Hastelloy were prepared, where the SmBCO film was spread along the tape length. The critical current was measured using the non-contact Hall-probe method, and the field dependences of the critical current under a high magnetic field were measured. The superconducting properties of the samples under a magnetic field were highly influenced by the composition of the SmBCO film. Furthermore, elemental mapping of the high-Jc SmBCO-coated conductor was measured by transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (TEM-EDX). Finally, we confirmed the Sm-related secondary phases take the role of pinning centers.

Ion beam sputter etching and deposition of fluoropolymers

NASA Technical Reports Server (NTRS)

Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

1978-01-01

Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

Growth and Characterization of the Evaporated Quaternary Absorber Cu2FeSnS4 for Solar Cell Applications

NASA Astrophysics Data System (ADS)

Oueslati, Hiba; Ben Rabeh, Mohamed; Kanzari, Mounir

2018-03-01

Cu2FeSnS4 (CFTS) was synthesized by direct fusion of high-purity elemental copper, iron, tin and sulfur. CFTS thin films were deposited on glass substrates heated by single source vacuum thermal evaporation, after which the obtained samples were annealed under a sulfur atmosphere in a sealed quartz tube at 400°C for 1 h in order to optimize the CFTS stannite phase. The substrate temperature was varied from room temperature to 200°C. The formation of a stannite structure with (112), (200) and (004) planes in the powder and thin films was confirmed using x-ray diffraction measurements and the crystallites were found to have a preferred orientation along the (112) direction. Optical measurements analysis showed that after the sulfurization process the layers have a relatively high absorption coefficient close to 105 cm-1 in the visible spectrum. The films show a direct optical band gap in the range 1.30-1.63 eV for substrate temperature varied from room temperature to 200°C. All samples revealed p-type conductivity as determined by the hot probe method.

Lubrication model for evaporation of binary sessile drops

NASA Astrophysics Data System (ADS)

Williams, Adam; Sáenz, Pedro; Karapetsas, George; Matar, Omar; Sefiane, Khellil; Valluri, Prashant

2017-11-01

Evaporation of a binary mixture sessile drop from a solid substrate is a highly dynamic and complex process with flow driven both thermal and solutal Marangoni stresses. Experiments on ethanol/water drops have identified chaotic regimes on both the surface and interior of the droplet, while mixture composition has also been seen to govern drop wettability. Using a lubrication-type approach, we present a finite element model for the evaporation of an axisymmetric binary drop deposited on a heated substrate. We consider a thin drop with a moving contact line, taking also into account the commonly ignored effects of inertia which drives interfacial instability. We derive evolution equations for the film height, the temperature and the concentration field considering that the mixture comprises two ideally mixed volatile components with a surface tension linearly dependent on both temperature and concentration. The properties of the mixture such as viscosity also vary locally with concentration. We explore the parameter space to examine the resultant effects on wetting and evaporation where we find qualitative agreement with experiments in both these areas. This enables us to understand the nature of the instabilities that spontaneously emerge over the drop lifetime. EPSRC - EP/K00963X/1.

Wafer-Level Vacuum Packaging of Smart Sensors.

PubMed

Hilton, Allan; Temple, Dorota S

2016-10-31

The reach and impact of the Internet of Things will depend on the availability of low-cost, smart sensors-"low cost" for ubiquitous presence, and "smart" for connectivity and autonomy. By using wafer-level processes not only for the smart sensor fabrication and integration, but also for packaging, we can further greatly reduce the cost of sensor components and systems as well as further decrease their size and weight. This paper reviews the state-of-the-art in the wafer-level vacuum packaging technology of smart sensors. We describe the processes needed to create the wafer-scale vacuum microchambers, focusing on approaches that involve metal seals and that are compatible with the thermal budget of complementary metal-oxide semiconductor (CMOS) integrated circuits. We review choices of seal materials and structures that are available to a device designer, and present techniques used for the fabrication of metal seals on device and window wafers. We also analyze the deposition and activation of thin film getters needed to maintain vacuum in the ultra-small chambers, and the wafer-to-wafer bonding processes that form the hermetic seal. We discuss inherent trade-offs and challenges of each seal material set and the corresponding bonding processes. Finally, we identify areas for further research that could help broaden implementations of the wafer-level vacuum packaging technology.

Wafer-Level Vacuum Packaging of Smart Sensors

PubMed Central

Hilton, Allan; Temple, Dorota S.

2016-01-01

The reach and impact of the Internet of Things will depend on the availability of low-cost, smart sensors—“low cost” for ubiquitous presence, and “smart” for connectivity and autonomy. By using wafer-level processes not only for the smart sensor fabrication and integration, but also for packaging, we can further greatly reduce the cost of sensor components and systems as well as further decrease their size and weight. This paper reviews the state-of-the-art in the wafer-level vacuum packaging technology of smart sensors. We describe the processes needed to create the wafer-scale vacuum microchambers, focusing on approaches that involve metal seals and that are compatible with the thermal budget of complementary metal-oxide semiconductor (CMOS) integrated circuits. We review choices of seal materials and structures that are available to a device designer, and present techniques used for the fabrication of metal seals on device and window wafers. We also analyze the deposition and activation of thin film getters needed to maintain vacuum in the ultra-small chambers, and the wafer-to-wafer bonding processes that form the hermetic seal. We discuss inherent trade-offs and challenges of each seal material set and the corresponding bonding processes. Finally, we identify areas for further research that could help broaden implementations of the wafer-level vacuum packaging technology. PMID:27809249

New bio-active, antimicrobial and adherent coatings of nanostructured carbon double-reinforced with silver and silicon by Matrix-Assisted Pulsed Laser Evaporation for medical applications

NASA Astrophysics Data System (ADS)

Duta, L.; Ristoscu, C.; Stan, G. E.; Husanu, M. A.; Besleaga, C.; Chifiriuc, M. C.; Lazar, V.; Bleotu, C.; Miculescu, F.; Mihailescu, N.; Axente, E.; Badiceanu, M.; Bociaga, D.; Mihailescu, Ion N.

2018-05-01

We report on Matrix-Assisted Pulsed Laser Evaporation (MAPLE) deposition of Carbon thin films, simple or reinforced with intended concentrations of Ag and Si. A KrF∗ (λ = 248 nm, τFWHM ≤ 25 ns, ν = 10 Hz) excimer laser was used for irradiation. The effect of a post-deposition thermal treatment in vacuum was studied. Besides detailed morphological, compositional, structural and pull-out adherence characterizations, the potential of the carbonaceous films for medical applications was investigated in vitro by anti-biofilm and cytocompatibility assays. The microscopic images evidenced no delaminations. Micro-Raman spectroscopy revealed a graphitization tendency depending on preparation conditions, thermal treatment and reinforcing agents' presence. Adherence values improved considerably after thermal treatment. In vitro biological evaluation showed that the films containing ∼1.85 at.% Ag were non-cytotoxic for MG63 cells, while eliciting a limited antimicrobial activity. The increase of Ag content to 3.6 at.% results in a significant enhancement of antimicrobial activity, whilst maintaining the cytotoxic action and adherence characteristics at acceptable levels. We propose a new class of metamaterials based on C reinforced with Ag and Si obtained by MAPLE for medical applications, i.e. the prevention and treatment of various infections associated with biofilms developed on implants and other medical equipments.

Large-area fluidic assembly of single-walled carbon nanotubes through dip-coating and directional evaporation

NASA Astrophysics Data System (ADS)

Kim, Pilnam; Kang, Tae June

2017-12-01

We present a simple and scalable fluidic-assembly approach, in which bundles of single-walled carbon nanotubes (SWCNTs) are selectively aligned and deposited by directionally controlled dip-coating and solvent evaporation processes. The patterned surface with alternating regions of hydrophobic polydimethyl siloxane (PDMS) (height 100 nm) strips and hydrophilic SiO2 substrate was withdrawn vertically at a constant speed ( 3 mm/min) from a solution bath containing SWCNTs ( 0.1 mg/ml), allowing for directional evaporation and subsequent selective deposition of nanotube bundles along the edges of horizontally aligned PDMS strips. In addition, the fluidic assembly was applied to fabricate a field effect transistor (FET) with highly oriented SWCNTs, which demonstrate significantly higher current density as well as high turn-off ratio (T/O ratio 100) as compared to that with randomly distributed carbon nanotube bundles (T/O ratio <10).

Multi-Evaporator Miniature Loop Heat Pipe for Small Spacecraft Thermal Control

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura; Douglas, Donya

2008-01-01

This paper presents the development of the Thermal Loop experiment under NASA's New Millennium Program Space Technology 8 (ST8) Project. The Thermal Loop experiment was originally planned for validating in space an advanced heat transport system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and multiple condensers. Details of the thermal loop concept, technical advances and benefits, Level 1 requirements and the technology validation approach are described. An MLHP breadboard has been built and tested in the laboratory and thermal vacuum environments, and has demonstrated excellent performance that met or exceeded the design requirements. The MLHP retains all features of state-of-the-art loop heat pipes and offers additional advantages to enhance the functionality, performance, versatility, and reliability of the system. In addition, an analytical model has been developed to simulate the steady state and transient operation of the MHLP, and the model predictions agreed very well with experimental results. A protoflight MLHP has been built and is being tested in a thermal vacuum chamber to validate its performance and technical readiness for a flight experiment.

Solid sulfur in vacuum: Sublimation effects on surface microtexture, color and spectral reflectance, and applications to planetary surfaces

NASA Technical Reports Server (NTRS)

Nash, D. B.

1987-01-01

A form of sulfur that is white at room temperature and very fluffy in texture has been found in laboratory experiments on the effects of vacuum sublimation (evaporation) on solid sulfur. This work is an outgrowth of proton sputtering experiments on sulfur directed toward understanding Jovian magnetospheric effects on the surface of Io. Fluffy white sulfur is formed on the surface of solid yellow, tan, or brown sulfur melt freezes in vacuum by differential (fractional) evaporation of two or more sulfur molecular species present in the original sulfur; S(8) ring sulfur is thought to be the dominant sublimination phase lost to the vacuum sink, and polymeric chain sulfur S(u) the dominant residual phase that remains in place, forming the residual fluffy surface layer. The reflectance spectrum of the original sulfur surface is greaty modified by formation of the fluffy layer: the blue absorption band-edge and shoulder move 0.05 to 0.06 microns toward shorter wavelengths resulting in a permanent increase in reflectivity near 0.42 to 0.46 microns; the UV reflectivity below 0.40 microns is reduced. This form of sulfur should exist in large quantity on the surface of Io, especially in hotspot regions if there is solid free sulfur there that has solidified from a melt. Its color and spectra will indicate relative crystallization age on a scale of days to months and/or surface temperature distribution history.

Indian Vacuum Society: The Indian Vacuum Society

NASA Astrophysics Data System (ADS)

Saha, T. K.

2008-03-01

The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

Self-assembly of colloidal particles from evaporating droplets: role of DLVO interactions and proposition of a phase diagram.

PubMed

Bhardwaj, Rajneesh; Fang, Xiaohua; Somasundaran, Ponisseril; Attinger, Daniel

2010-06-01

The shape of deposits obtained from drying drops containing colloidal particles matters for technologies such as inkjet printing, microelectronics, and bioassay manufacturing. In this work, the formation of deposits during the drying of nanoliter drops containing colloidal particles is investigated experimentally with microscopy and profilometry, and theoretically with an in-house finite-element code. The system studied involves aqueous drops containing titania nanoparticles evaporating on a glass substrate. Deposit shapes from spotted drops at different pH values are measured using a laser profilometer. Our results show that the pH of the solution influences the dried deposit pattern, which can be ring-like or more uniform. The transition between these patterns is explained by considering how DLVO interactions such as the electrostatic and van der Waals forces modify the particle deposition process. Also, a phase diagram is proposed to describe how the shape of a colloidal deposit results from the competition among three flow patterns: a radial flow driven by evaporation at the wetting line, a Marangoni recirculating flow driven by surface tension gradients, and the transport of particles toward the substrate driven by DLVO interactions. This phase diagram explains three types of deposits commonly observed experimentally, such as a peripheral ring, a small central bump, or a uniform layer. Simulations and experiments are found in very good agreement.

Development of porous metal oxide thin films by co-evaporation

NASA Astrophysics Data System (ADS)

Tesfamichael, T.; Motta, Nunzio; Bostrom, Thor; Bell, J. M.

2007-03-01

This paper focuses on the development of mixed metal oxide thin films and physical characterization of the films. The films were produced by co-evaporation of titanium oxide and tungsten oxide powders. This allowed the development of titanium oxide-tungsten oxide films as analyzed using XPS. Examination in the SEM and AFM showed that the films were nanoporous with the pore size and pore orientation varying as a function of the deposition angle. UV-vis spectra of the films show an increase of transmittance with increasing deposition angle which is attributed to the structure and porosity of the films. Raman analysis indicated that the as-deposited films have broad and weak Raman characteristics, attributed to the nanocrystal nature of the films and the presence of defects, and the peak broadening deceases after annealing the film, as expected.

Prospects for Ultra-Stable Timekeeping with Sealed Vacuum Operation in Multi-Pole Linear Ion Trap Standards

NASA Technical Reports Server (NTRS)

Burt, Eric A.; Tjoelker, R. L.

2007-01-01

A recent long-term comparison between the compensated multi-pole Linear Ion Trap Standard (LITS) and the laser-cooled primary standards via GPS carrier phase time transfer showed a deviation of less than 2.7x10(exp -17)/day. A subsequent evaluation of potential drift contributors in the LITS showed that the leading candidates are fluctuations in background gases and the neon buffer gas. The current vacuum system employs a "flow-through" turbomolecular pump and a diaphragm fore pump. Here we consider the viability of a "sealed" vacuum system pumped by a non-evaporable getter for long-term ultra-stable clock operation. Initial tests suggests that both further stability improvement and longer mean-time-between-maintenance can be achieved using this approach

Dry deposition of reduced and reactive nitrogen: A surrogate surfaces approach

NASA Astrophysics Data System (ADS)

Shahin, Usama Mohammed

Nitrogen deposition constitutes an important component of acidic deposition to terrestrial surfaces. However, deposition flux and ambient concentration measurement methods and are still under development. A new sampler using water as a surrogate surface was developed in the Department of Environmental Engineering at Illinois Institute of Technology. This study investigated nitrate and ammonia dry deposition to the water surface sampler, a Nylasorb filter, a citric acid impregnated filter, and a greased strip on the dry deposition plate. The nitrogen containing species that may be responsible for nitrate dry deposition to the WSS include nitrogen monoxide (NO), nitrogen dioxide (NO2), peroxyacetyl nitrate (PAN), nitrous acid (HNO2), nitric acid (HNO3), and particulate nitrate. The experimental measurements showed that HNO3 and particulate nitrate are the major nitrate contributors to the WSS. Ammonia sources to the water surface are ammonia gas (NH3) and ammonium (NH4+). The experimental results showed that these two species are the sole sources to ammonium deposition. Comparison between the measured deposition velocity of SO2, and HNO3, shows that their dry deposition velocities are statistically the same at the 95% confidence level and NH3 deposition velocity and the water evaporation rate are also the same. It was also shown that the air side MTC of two different compounds were correlated to the square root of the inverse of the molecular weight for compounds. The measured MTC was tested by the application of two models, the resistance model and the water evaporation model. The resistance model prediction of the MTC was very close to the measured value but the evaporation model prediction was not. This result is compatible with the finding of Yi, (1997) who used the same WSS for measurements of SO2. The experimental data collected in this research project was used to develop an empirical model to measure the MTC that is [kl/over D] = 0.0426 ([lv/rho/over /mu])0

Atomic Layer Deposition on Gram Quantities of Multi-Walled Carbon Nanotubes

DTIC Science & Technology

2009-06-03

the amount of reactant that is lost to the vacuum pump . Recent work has demonstrated the feasibility of ALD on gram quantities of nanopowders in a...and left to outgas under vacuum for 24 h. Vacuum was obtained using a dual-stage rotary vane pump . Pressure was monitored with a Baratron capacitance...Atomic layer deposition on gram quantities of multi-walled carbon nanotubes This article has been downloaded from IOPscience. Please scroll down to

Introducing ultrasonic falling film evaporator for moderate temperature evaporation enhancement.

PubMed

Dehbani, Maryam; Rahimi, Masoud

2018-04-01

In the present study, Ultrasonic Falling Film (USFF), as a novel technique has been proposed to increase the evaporation rate of moderate temperature liquid film. It is a proper method for some applications which cannot be performed at high temperature, such as foodstuff industry, due to their sensitivity to high temperatures. Evaporation rate of sodium chloride solution from an USFF on an inclined flat plate compared to that for Falling Film without ultrasonic irradiation (FF) at various temperatures was investigated. The results revealed that produced cavitation bubbles have different effects on evaporation rate at different temperatures. At lower temperatures, size fluctuation and collapse of bubbles and in consequence induced physical effects of cavitation bubbles resulted in more turbulency and evaporation rate enhancement. At higher temperatures, the behavior was different. Numerous created bubbles joined together and cover the plate surface, so not only decreased the ultrasound vibrations but also reduced the evaporation rate in comparison with FF. The highest evaporation rate enhancement of 353% was obtained at 40 °C at the lowest Reynolds number of 250. In addition, the results reveal that at temperature of 40 °C, USFF has the highest efficiency compared to FF. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterizations of the TiO2-x films synthesized by e-beam evaporation for endovascular applications

NASA Astrophysics Data System (ADS)

Lin, Zeng; Lee, In-Seop; Choi, Yoon-Jeong; Noh, In-Sup; Chung, Sung-Min

2009-02-01

Different chemical states of titanium oxide films were deposited on commercially pure Ti (CP Ti) by electron-beam evaporation at different oxygen flow rates to examine a possibility of their applications to endovascular stents. The surface morphology, chemical composition and crystal structure of the obtained titanium oxide films were analyzed by FE-SEM, XPS and XRD, respectively. As a function of the deposition parameters employed, the obtained titanium oxide films demonstrated different mixtures of anatase phase, Ti2O3 and TiO. By the formation of titanium oxide film on the CP Ti plate, the contact angle was decreased and the cellular activity of porcine aortic smooth muscle cells was increased. Post-deposition annealing was also found to be an important factor to achieve advantageous biocompatibility. When haemocompatibility was investigated by observing adhesion of blood platelets from platelet-rich plasma, less platelet adhesion was observed on titanium oxide films. These results indicated that titanium oxide film synthesized by e-beam evaporation could be applicable to coronary stents.

Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

PubMed

Schroeder, J L; Thomson, W; Howard, B; Schell, N; Näslund, L-Å; Rogström, L; Johansson-Jõesaar, M P; Ghafoor, N; Odén, M; Nothnagel, E; Shepard, A; Greer, J; Birch, J

2015-09-01

We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (<1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (<11°), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

Niobium thin film coating on a 500-MHz copper cavity by plasma deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haipeng Wang; Genfa Wu; H. Phillips

2005-05-16

A system using an Electron Cyclotron Resonance (ECR) plasma source for the deposition of a thin niobium film inside a copper cavity for superconducting accelerator applications has been designed and is being constructed. The system uses a 500-MHz copper cavity as both substrate and vacuum chamber. The ECR plasma will be created to produce direct niobium ion deposition. The central cylindrical grid is DC biased to control the deposition energy. This paper describes the design of several subcomponents including the vacuum chamber, RF supply, biasing grid and magnet coils. Operational parameters are compared between an operating sample deposition system andmore » this system. Engineering work progress toward the first plasma creation will be reported here.« less

Improving X-Ray Optics via Differential Deposition

NASA Technical Reports Server (NTRS)

Kilaru, Kiranmayee; Ramsey, Brian D.; Atkins, Carolyn

2017-01-01

Differential deposition, a post-fabrication figure correction technique, has the potential to significantly improve the imaging quality of grazing-incidence X-ray optics. DC magnetron sputtering is used to selectively coat the mirror in order to minimize the figure deviations. Custom vacuum chambers have been developed at NASA MSFC that will enable the implementation of the deposition on X-ray optics. A factor of two improvement has been achieved in the angular resolution of the full-shell X-ray optics with first stage correction of differential deposition. Current efforts are focused on achieving higher improvements through efficient implementation of differential deposition.

Friction and wear of plasma-deposited diamond films

NASA Technical Reports Server (NTRS)

Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan; Barnes, Paul N.; Jackson, Howard E.

1993-01-01

Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02 to 0.04 in humid air and in dry nitrogen, but 1.5 to 1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen.