Fatigue and Fracture of Polycrystalline Silicon and Diamond MEMS at Room and Elevated Temperatures

2006 ◽  
Author(s):  
Ioannis Chasiotis
Keyword(s):  
Polycrystalline Silicon ◽  
Elevated Temperatures ◽  
Fatigue And Fracture ◽  
Diamond Mems

Hydrogen-Induced Metastability of Polycrystalline Silicon

1995 ◽  
Vol 378 ◽  
Author(s):  
N. H. Nickel
Keyword(s):  
Polycrystalline Silicon ◽  
Elevated Temperatures ◽  
Prolonged Exposure ◽  
Dark Conductivity ◽  
Type Conversion

AbstractThe presence of H in polycrystalline silicon gives rise to new and hitherto unexpected phenomena. In this paper two of the most recent observations are reviewed: (i) Hydrogen-induced metastable changes of the dark conductivity due to the formation and dissociation of an electrically active H complex and (ii) the generation of acceptor states during prolonged exposure of poly-Si to monatomic H at elevated temperatures. The observed type conversion is clearly due to the diffusion of excess H from the plasma since it does not occur during exposure to other species such as oxygen.

Fatigue and Fracture Estimation for Metallic Components: Some Current Methods and Future Developments

1995 ◽  
Vol 117 (B) ◽  
pp. 121-127
Author(s):  
D. V. Nelson ◽  
Sheri D. Sheppard
Keyword(s):  
Recent Work ◽  
Environmental Effects ◽  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Metallic Alloys ◽  
Future Developments ◽  
Fatigue And Fracture ◽  
Mechanical Components

Current approaches widely used in fatigue and fracture evaluations of mechanical components are summarized. Metallic alloys, and fatigue and fracture behavior in the absence of environmental effects such as corrosion or elevated temperatures, are considered. Certain shortcomings in the approaches are then discussed, followed by samples of recent work to improve the capabilities to make fatigue and fracture assessments. Finally, future developments that could further enhance those capabilities are suggested.

Fatigue and Fracture Estimation for Metallic Components: Some Current Methods and Future Developments

1995 ◽  
Vol 117 (B) ◽  
pp. 121-127 ◽  
Author(s):  
D. V. Nelson ◽  
Sheri D. Sheppard
Keyword(s):  
Recent Work ◽  
Environmental Effects ◽  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Metallic Alloys ◽  
Future Developments ◽  
Fatigue And Fracture ◽  
Mechanical Components

Current approaches widely used in fatigue and fracture evaluations of mechanical components are summarized. Metallic alloys, and fatigue and fracture behavior in the absence of environmental effects such as corrosion or elevated temperatures, are considered. Certain shortcomings in the approaches are then discussed, followed by samples of recent work to improve the capabilities to make fatigue and fracture assessments. Finally, future developments that could further enhance those capabilities are suggested.

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Observations oh Nucleation and Growth of Voids in Nickel

1970 ◽  
Vol 28 ◽  
pp. 414-415
Author(s):  
J. L. Brimhall ◽  
H. E. Kissinger ◽  
B. Mastel
Keyword(s):  
High Purity ◽  
Growth Stage ◽  
Elevated Temperatures ◽  
Early Growth ◽  
Nucleation And Growth ◽  
Pure Nickel ◽  
Different Temperatures ◽  
Total Fluence ◽  
Neutron Exposure ◽  
Growth Of Voids

Some information on the size and density of voids that develop in several high purity metals and alloys during irradiation with neutrons at elevated temperatures has been reported as a function of irradiation parameters. An area of particular interest is the nucleation and early growth stage of voids. It is the purpose of this paper to describe the microstructure in high purity nickel after irradiation to a very low but constant neutron exposure at three different temperatures.Annealed specimens of 99-997% pure nickel in the form of foils 75μ thick were irradiated in a capsule to a total fluence of 2.2 × 1019 n/cm2 (E > 1.0 MeV). The capsule consisted of three temperature zones maintained by heaters and monitored by thermocouples at 350, 400, and 450°C, respectively. The temperature was automatically dropped to 60°C while the reactor was down.

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