Temperature and Flux dependence of ion induced ripple: a way to study defect and relaxation kinetics during ion bombardment

2004 ◽  
Vol 849 ◽  
Author(s):  
Wai Lun Chan
Keyword(s):  
High Temperature ◽  
Surface Defect ◽  
Ion Beam ◽  
Linear Instability ◽  
Low Energy ◽  
Ion Sputtering ◽  
Thermally Induced ◽  
Formation Kinetics ◽  
Lower Temperature Range ◽  
Lower Temperature

ABSTRACTWe have measured the temperature and ion flux dependence of the ripple wavelength on a Cu(001) surface during low energy ion sputtering. We analyze these results in terms of a linear instability model and identify different experimentally observed behavior with different mechanisms of relaxation and surface defect kinetics. In a high temperature regime, diffusing species on the surface are mainly thermally induced while in a lower temperature range, the diffusing species are ion beam induced. At even lower temperature, thermal diffusion is deactivated and the surface relaxes through an athermal mechanism. We define a transition between different defects formation kinetics in temperature and flux phase space and discuss how the defect kinetics model can be extended to different materials system.

Radiation Enhanced Diffusion in Mgo

1994 ◽  
Vol 373 ◽  
Author(s):  
Andrew I. Van Sambeek ◽  
R.S. Averback ◽  
C.P. Flynn ◽  
M.H. Yang
Keyword(s):  
Diffusion Coefficient ◽  
Activation Enthalpy ◽  
Ion Beam ◽  
Charge Compensation ◽  
Cation Sublattice ◽  
Loop Formation ◽  
Temperature Range ◽  
Measured Activation ◽  
Lower Temperature Range ◽  
Lower Temperature

AbstractMeasurements of marker spreading following 2.0 MeV Kr+ irradiation at 25 to 1300°C have been performed on MgO samples containing O18, Ca and Zn buried tracer atoms. Ion beam mixing at room temperature on both sublattices was approximately 2.0 to 3.0 A5/eV. From 600 to 1000°C, the apparent activation enthalpy for diffusion on the anion sublattice (O18) was 0.35 eV and the diffusion coefficient was linear in the irradiation flux. From 1150 to 1300°C the measured activation enthalpy was 4.1 eV and the diffusion coefficient was proportional to the square root of flux. The measured activation enthalpy on the cation sublattice was roughly 0.30 eV up to 700°C for both Ca or Zn doped samples. Measurable extrinsic thermal diffusion from vacancies present for trivalent impurity charge compensation occurred above this temperature, complicating the analysis at higher temperatures. The observed kinetics in the lower temperature range are most likely controlled by interstitial loop formation. In the higher temperature range, vacancy traps with a binding energy of approximately 2 eV could account for the high activation enthalpy.

The Application of Gas-Turbine Technique to Steam Power

1950 ◽  
Vol 162 (1) ◽  
pp. 209-238 ◽  
Author(s):  
J. F. Field
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Steam Power ◽  
Temperature Range ◽  
Power Stations ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
External Combustion ◽  
Steam Cycle

Early attempts to adapt the mechanism of the turbine to the air- or gas-engine were frustrated by the losses in the compressor, but in the last twenty years improvements in the efficiency of the latter, together with better high-temperature metals for the turbine, have enabled the gas turbine to approach the efficiency of the steam turbine. The gas turbine has to operate from a much higher temperature and with more effective high-temperature regeneration to achieve this. On the other hand it cannot utilize heat down to anything like the same lower temperature as steam power. Most regenerative gas-turbine cycles are therefore more efficient than the steam cycle at the upper temperature range, and less efficient at the lower temperature range. Now that the Rankine steam cycle has reached 1,000 deg. F., a given increment of temperature has much less effect on the steam turbine than on the gas turbine. The paper describes a condensing gas-turbine† cycle with external combustion, which utilizes orthodox gas-turbine and steam-turbine components in such a manner that the thermodynamic advantages of the two in the respective temperature ranges mentioned above are combined to give a higher thermal efficiency than either the steam or the gas turbine is capable of alone, and with the prospective ability to utilize almost any fuel. A great improvement may thus be made possible in the fuel economy of condensing steam power stations, steamship propulsion, and steam locomotives, and in the ratio of mechanical power to heat in combined power and process or district heat production. It may become commercially worth while, apart from the saving in coal, to eliminate a large proportion of condensing operation on land in the winter months. By integrating the fuel-using industries in this manner it should be possible to save at least fifty-million tons of coal per annum on the present aggregate output of power and heat, with a further saving of eleven-million tons of locomotive coal. This should enable the nation to afford much more liberal use of power and heat and thus achieve much greater production in transport and industry.

FANSTEEL 291 METAL

Alloy Digest ◽  
1973 ◽  
Vol 22 (11) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Base Alloy ◽  
Weight Ratio ◽  
High Strength ◽  
Heat Treating ◽  
Temperature Range ◽  
Temperature Performance ◽  
Lower Temperature Range ◽  
Lower Temperature

Abstract FANSTEEL 291 METAL is a columbium-base alloy that can be readily fabricated, machined and welded. It is used in the high-temperature range 2800-3500 F where excellent strength-to-weight ratio can be used to advantage. It is also used in the lower temperature range 2000-2700 F because of its availability and fabricability which may be of more importance than high strength alone. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance and corrosion resistance as well as heat treating, machining, and joining. Filing Code: Cb-20. Producer or source: Fansteel Metallurgical Corporation.

Structure of Al-N Films Deposited by a Quantitative Dual Ion Beam Process

1983 ◽  
Vol 27 ◽  
Author(s):  
H.T.G. Hentzell ◽  
J.M.E. Harper ◽  
J.J. Cuomo
Keyword(s):  
Ion Beam ◽  
Film Surface ◽  
Ion Bombardment ◽  
Preferred Orientation ◽  
Low Energy ◽  
Ion Sputtering ◽  
Pronounced Change ◽  
Beam System ◽  
Axis Parallel ◽  
N Flux

ABSTRACTWe describe the structure of Al-N films deposited with N/Al ratios varying from 0 to 1. A dual ion beam system supplies the Al flux by inert ion sputtering, and the N flux by low energy (100–500 eV) N2+ ion bombardment of the growing film. For N/Al < 1, a cermet structure forms with large Al grains mixed with AlN. Above the composition N/Al = 1, excess N is rejected from the AlN. The AlN films show a pronounced change in preferred orientation from c-axis perpendicular to the film surface, to c-axis parallel to the film surface with increasing N2+ energy

scholarly journals Low-energy ion beam modified surface property and mechanism of high temperature superconductor YBa2Cu3O7- thin film

2018 ◽  
Vol 67 (3) ◽  
pp. 036103
Author(s):  
Wang San-Sheng ◽  
Li Fang ◽  
Wu Han ◽  
Zhang Zhu-Li ◽  
Jiang Wen ◽  
...  
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Surface Property ◽  
High Temperature Superconductor ◽  
Ion Beam ◽  
Low Energy ◽  
Modified Surface

EPDM Vulcanization and High Temperature Compression Set

1970 ◽  
Vol 43 (5) ◽  
pp. 1040-1054 ◽  
Author(s):  
F. P. Baldwin
Keyword(s):  
High Temperature ◽  
Crosslink Density ◽  
Reduction Process ◽  
Exact Nature ◽  
Competitive Balance ◽  
Rank Reduction ◽  
Thermally Induced ◽  
Compression Set ◽  
Lower Temperature ◽  
Free Sulfur

Abstract The data presented are suggestive of the following conclusions regarding the vulcanization behavior and high temperature compression set properties of low unsaturation EPDM polymers: 1. The olefinic residue derived from ENB is more reactive in conventional sulfur vulcanization than is the residue from MNB. However, the ENB residue is more prone to reversion reactions. 2. The structure of the olefinic residue present can have important bearing on the exact nature at the crosslinks produced at a given crosslink density. 3. The conversion of high to lower sulfur rank crosslinks appears to occur partly by a thermally induced interconversion process and partly by concerted reactions in which crosslink bond scission does not occur as a discrete step. Both the nature and the concentration of accelerator present should have important bearing on the competitive balance between these two processes as should the presence of free sulfur. 4. Since the presence of free sulfur can procrastinate the sulfur crosslink rank reduction process, the observed low rate (relative to highly unsaturated elastomers) of conversion of polysulfidic to lower rank crosslinks must be associated with the absence of a large “sink” for sulfur. Thus with a given curing system, stable crosslinks should be generated faster the higher the level of unsaturation present and the lower the sulfur concentration. 5. High temperature compression set performance is influenced not only by the formation of new crosslinks during heating under compression but also by the interconversion of polysulfidic linkages present in the initial vulcanizates. Thus two polymers containing different olefin residues can exhibit identical set properties but for different reasons. 6. In practical terms both crosslink density and stability can be maximized by a combination of a short, high temperature forming cure followed by a long heat soak at a lower temperature. This observation should have important bearing on the economics of production of quality mechanical goods from low unsaturation elastomers via injection molding, the heat soaking step being paid for by the reduction in accelerator cost and molding cycle time.

Chemical Precursors for GaAs Etching with low Energy ion Beams: Chlorine adsorption on GaAs(100)

1991 ◽  
Vol 223 ◽  
Author(s):  
Richard B. Jackman ◽  
Glenn C. Tyrrell ◽  
Duncan Marshall ◽  
Catherine L. French ◽  
John S. Foord
Keyword(s):  
Ion Beam ◽  
Ion Beams ◽  
Low Energy ◽  
Ion Beam Etching ◽  
Chlorine Adsorption

ABSTRACTThis paper addresses the issue of chlorine adsorption on GaAs(100) with respect to the mechanisms of thermal and ion-enhanced etching. The use of halogenated precursors eg. dichloroethane is also discussed in regard to chemically assisted ion beam etching (CAIBE).

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

TEM Sample Preparation by Single-Sided Low-Energy Ion Beam Etching

2011 ◽  
Author(s):  
Liew Kaeng Nan ◽  
Lee Meng Lung
Keyword(s):  
Sample Preparation ◽  
Semiconductor Device ◽  
Ion Beam ◽  
Critical Dimension ◽  
Low Energy ◽  
Ex Situ ◽  
Good Image Quality ◽  
Ion Beam Etching ◽  
Device Structures ◽  
Common Technique

Abstract Conventional FIB ex-situ lift-out is the most common technique for TEM sample preparation. However, the scaling of semiconductor device structures poses great challenge to the method since the critical dimension of device becomes smaller than normal TEM sample thickness. In this paper, a technique combining 30 keV FIB milling and 3 keV ion beam etching is introduced to prepare the TEM specimen. It can be used by existing FIBs that are not equipped with low-energy ion beam. By this method, the overlapping pattern can be eliminated while maintaining good image quality.

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