TEM sample preparation of wear-tested room-temperature pulsed-laser-deposited thin films of MoS2 by ultramicrotomy

1993 ◽  
Vol 51 ◽  
pp. 1118-1119
Author(s):  
Pamela F. Lloyd ◽  
Scott D. Walck
Keyword(s):  
Thin Films ◽  
Sample Preparation ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Ultra High Vacuum ◽  
Wear Testing ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Aerospace Applications

Pulsed laser deposition (PLD) is a novel technique for the deposition of tribological thin films. MoS2 is the archetypical solid lubricant material for aerospace applications. It provides a low coefficient of friction from cryogenic temperatures to about 350°C and can be used in ultra high vacuum environments. The TEM is ideally suited for studying the microstructural and tribo-chemical changes that occur during wear. The normal cross sectional TEM sample preparation method does not work well because the material’s lubricity causes the sandwich to separate. Walck et al. deposited MoS2 through a mesh mask which gave suitable results for as-deposited films, but the discontinuous nature of the film is unsuitable for wear-testing. To investigate wear-tested, room temperature (RT) PLD MoS2 films, the sample preparation technique of Heuer and Howitt was adapted.Two 300 run thick films were deposited on single crystal NaCl substrates. One was wear-tested on a ball-on-disk tribometer using a 30 gm load at 150 rpm for one minute, and subsequently coated with a heavy layer of evaporated gold.

scholarly journals Annealing Condition Effects on the Structural Properties of FePt Nanoparticles Embedded in MgO via Pulsed Laser Deposition

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 131
Author(s):  
Tingting Xiao ◽  
Qi Yang ◽  
Jian Yu ◽  
Zhengwei Xiong ◽  
Weidong Wu
Keyword(s):  
Pulsed Laser Deposition ◽  
Room Temperature ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Annealing Process ◽  
Ultra High Vacuum ◽  
Laser Deposition ◽  
Fept Nanoparticles ◽  
Annealing Conditions ◽  
Vacuum Atmosphere

FePt nanoparticles (NPs) were embedded into a single-crystal MgO host by pulsed laser deposition (PLD). It was found that its phase, microstructures and physical properties were strongly dependent on annealing conditions. Annealing induced a remarkable morphology variation in order to decrease its total free energy. H2/Ar (95% Ar + 5% H2) significantly improved the L10 ordering of FePt NPs, making magnetic coercivity reach 37 KOe at room temperature. However, the samples annealing at H2/Ar, O2, and vacuum all showed the presence of iron oxide even with the coverage of MgO. MgO matrix could restrain the particles’ coalescence effectively but can hardly avoid the oxidation of Fe since it is extremely sensitive to oxygen under the high-temperature annealing process. This study demonstrated that it is essential to anneal FePt in a high-purity reducing or ultra-high vacuum atmosphere in order to eliminate the influence of oxygen.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

MAGNETIC TRANSITION IN QUASI ONE DIMENSIONAL WIRES AND THIN FILMS OF GADOLINIUM

1993 ◽  
Vol 07 (01n03) ◽  
pp. 496-499
Author(s):  
NAUSHAD ALI ◽  
J. T. MASDEN ◽  
PEGGY HILL ◽  
ARTHUR CHIN
Keyword(s):  
Thin Films ◽  
Magnetic Transition ◽  
High Vacuum ◽  
Magnetic Ordering ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Ferromagnetic Transition ◽  
Sharp Drop ◽  
Cross Sectional ◽  
Thin Wires

Thin wires of gadolinium metal have been fabricated using a step lithographic technique with cross-sectional areas from 0.87 × 10−11 cm 2 to 58 × 10−11 cm 2. The thin films of gadolinium were deposited in a ultra high vacuum system by thermal evaporation with the thickness of films in the range 200Å to 1200Å. Resistivity data of Gd thin wires does not show evidence of bulk transition at T c ≈ 293 K (bulk) at all. However, a phase transition manifested as a sharp drop in resistivity of Gd thin wires is observed around 20 K. Thin films of Gd deposited on glass and sapphire substrates were used to measure the magnetic properties using a SQUID magnetometer. Films of thickness > 500Å show ferromagnetic transition around 290 K (close to bulk) and a small peak in the magnetization around 20 K is also observed. For Gd films of thickness ~ 200Å there is no evidence of ferromagnetic transition, however, the magnetization data clearly shows a peak in the neighborhood of 20 K. It appears that in the case of very thin films and thin wires of Gd we are observing a magnetic transition around 20 K. This transition may be due to magnetic ordering of the surface which has a transition temperature much smaller than the bulk ferromagnetic T c of 293 K.

Deposition of Borocarbides Thin Films by Pulsed Laser Ablation: Growth Parameters and Characterization

1999 ◽  
Vol 13 (09n10) ◽  
pp. 1049-1054 ◽  
Author(s):  
C. Ferdeghini ◽  
M.R. Cimberle ◽  
G. Grassano ◽  
D. Marre ◽  
M. Putti ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Growth Parameters ◽  
High Vacuum ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Film Structure ◽  
Ultra High Vacuum ◽  
Structure And Properties ◽  
Deposition Parameters

In this paper we report results on the growth of borocarbides ErNi 2 B 2C and DyNi 2 B 2 C thin films by an ultra high vacuum laser ablation technique. The dependence of the film structure and properties on the deposition parameters has been studied. Moreover the possibility to obtain superconducting films with a tungsten buffer layer on MgO substrates has been successfully checked. Here we present details on the deposition procedure as well as on the structural, morphological, and physical characterization.

scholarly journals Rare Earth - Fe2 Thin Films Study With Strata™

1996 ◽  
Vol 4 (6) ◽  
pp. 22-23
Author(s):  
J. M. Claude ◽  
J. F. Thiot ◽  
V. Oderno ◽  
C. Dufour
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Room Temperature ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Growth Direction ◽  
Ultra High Vacuum ◽  
Laves Phases ◽  
20 Nm ◽  
The Rare Earth

The Rare-Earth Laves phases RE-Fe2 (RE represent the Rare-Earth) show large magnetostrictive properties, especially at room temperature. These materials are well characterized when in bulk form, but they have rarely been studied as thin films and one can expect some important effects due to epitaxial growth.A few single crystal layers of RE-Fe2 have been studied (YFe2, TbFe2, DyFe2, ErFe2: and Dy0.7Tb0.3Fe2 known as Terfenol-D). The thickness of these different layers are between 5 and 20 nm and with [110] as a growth direction have been epitaxied. They have been deposited with a Molecular Beam Epitaxy (MBE) in an ultra high vacuum chamber. A [1120] sapphire substrate is recovered by a [110] niobium buffer. The RE and the iron are then co-deposited on the substrate which is maintained at 500°C. Lastly, an Yttrium layer is deposited on the Rare Earth material at a temperature close to ambient.

Characterization of pulsed laser deposited Zno-WS2 thin solid film lubricants

1995 ◽  
Vol 53 ◽  
pp. 558-559
Author(s):  
S. D. Walck ◽  
J. S. Zabinski ◽  
N.T. McDevitt ◽  
J. E. Bultman
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Low Temperatures ◽  
Wear Debris ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Chemical Changes ◽  
Aerospace Applications ◽  
Solid Film

ZnO-WS2 is a potential high temperature solid film lubricant for aerospace applications that exhibits adaptive lubricant behavior. An adaptive lubricant undergoes phase and/or chemical changes in response to thermal, environmental, and tribological conditions; with the resulting phase or wear debris also being lubricious. Pulsed laser deposited (PLD) ZnO-WS2 thin films deposited at room temperature (RT) and wear-tested at room temperature have been shown to have coefficients of friction of 0.04 or less which are comparable to WS2 films, but have much longer wear lives. In the as-deposited state, PLD ZnO-WS2 films are amorphous, but when wear-tested, the phases WS2, WO3, and ZnWO4 are produced. Of these, WS2 is a lubricant phase at low temperatures (⪯ ~450°C) while ZnWO4 is a lubricant phase above about 600°C. The purpose of this work was to characterize the microstructural and chemical changes that occur when the RT-PLD ZnO-WS2 films are heated in air.The RT-PLD ZnO-WS2 films were deposited in a system having a base pressure of 9×l0-7 Pa with a typical pressure during deposition of 6×10-5 Pa.

scholarly journals Room temperature control of spin states in a thin film of a photochromic iron(ii) complex

2018 ◽  
Vol 5 (3) ◽  
pp. 506-513 ◽  
Author(s):  
Lorenzo Poggini ◽  
Magdalena Milek ◽  
Giacomo Londi ◽  
Ahmad Naim ◽  
Giordano Poneti ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Temperature Control ◽  
Room Temperature ◽  
Spin Crossover ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Spin States ◽  
Molecular Spin

Thin films of a molecular spin crossover iron(ii) complex featuring a photochromic diarylethene-based ligand have been grown by sublimation in ultra-high vacuum on Au(111) and investigated by photoelectron spectroscopies.

In situ TEM sample preparation for surface-sensitive plane view imaging

1991 ◽  
Vol 49 ◽  
pp. 642-643
Author(s):  
R. Ai ◽  
D.N. Dunn ◽  
T.S. Savage ◽  
J.P. Zhang ◽  
L.D. Marks
Keyword(s):  
Sample Preparation ◽  
Surface Science ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
In Situ Tem ◽  
Preparation Technique ◽  
Surface Imaging ◽  
Resolution Electron ◽  
Electron Microscopes ◽  
Plane View

The recent development of ultra high vacuum high resolution electron microscopes has made it possible to use an electron microscope to study surface structures with atomic resolution. Although surface images of Au(110) 2x11 and Si(111) 7x72 reconstructions have been obtained, no standard TEM sample preparation technique for surface imaging has been developed for routine uses. In conventional surface science, the common method of producing an UHV clean sample is a combination of ion sputtering and annealing; can this process be used to produce TEM samples for surface imaging. Our studies show that clean, well order TEM samples can be achieved by this approach.

A Field Emission System For Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 298-299
Author(s):  
Michel Troyonal ◽  
Huei Pei Kuoal ◽  
Benjamin M. Siegelal
Keyword(s):  
Electron Microscope ◽  
Field Emission ◽  
Optical System ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Electron Optical System ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Emission System

A field emission system for our experimental ultra high vacuum electron microscope has been designed, constructed and tested. The electron optical system is based on the prototype whose performance has already been reported. A cross-sectional schematic illustrating the field emission source, preaccelerator lens and accelerator is given in Fig. 1. This field emission system is designed to be used with an electron microscope operated at 100-150kV in the conventional transmission mode. The electron optical system used to control the imaging of the field emission beam on the specimen consists of a weak condenser lens and the pre-field of a strong objective lens. The pre-accelerator lens is an einzel lens and is operated together with the accelerator in the constant angular magnification mode (CAM).

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