Mechanical tailoring of dislocation densities in SrTiO 3 at room temperature

A method has heen developed to determine the dislocation configuration in a polycrystalline specimen from the direction dependence of line broadening. The method is based on an analytical expression for the integral breadth due to microstrain from sets of parallel edge and/or screw dislocations on the specific slip systems. Analysis of the x-ray-diffraction measurements obtained from poly crystalline aluminium layers, deposited onto silicon wafers and subsequently annealed and cooled to room temperature, shows unequal densities and unequal changes of densities of dislocations with the Burgers vector parallel and with the Burgers vector inclined with respect to the surface of the layer. Stress relaxation and dislocation annihilation occur at room temperature. A model was developed to describe the dependency of the decrease of macrostress on the decrease of the dislocation density.

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Solution Growth and Characterization of Icosahedral Boron Arsenide (B12As2)

MRS Proceedings ◽

10.1557/opl.2011.502 ◽

2011 ◽

Vol 1307 ◽

Author(s):

C.E. Whiteley ◽

Y. Zhang ◽

A. Mayo ◽

J.H. Edgar ◽

Y. Gong ◽

...

Keyword(s):

Room Temperature ◽

Solution Growth ◽

High Quality ◽

Burgers Vector ◽

X Ray ◽

Dislocation Densities ◽

Boron Arsenide ◽

Viable Method ◽

Molten Nickel

ABSTRACTThe crystallographic properties of bulk icosahedral boron arsenide (B12As2) crystals grown by precipitation from molten nickel solutions were characterized. Large crystals (5-8 mm) were produced by dissolving the boron in nickel at 1150°C for 48-72 hours, reacting with arsenic vapor, and slowly cooling to room temperature. The crystals varied in color from black and opaque to clear and transparent. Raman spectroscopy, x-ray topography (XRT), and defect selective etching revealed that the B12As2 single crystals were high quality with low dislocation densities. Furthermore, XRT results suggest that the major face of the plate-like crystals was (111) type, while (100), (010) and (001) type facets were also observed optically. The predominant defect in these crystals was edge character growth dislocations with a <001> Burgers vector, and <-110> line direction. In short, XRT characterization shows that solution growth is a viable method for producing good quality B12As2 crystals.

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Blue II-VI laser Diodes and light Emitting Diodes

MRS Proceedings ◽

10.1557/proc-281-539 ◽

1992 ◽

Vol 281 ◽

Author(s):

R. L. Gunshor ◽

A. V. Nurmikko ◽

N. Otsuka

Keyword(s):

Quantum Wells ◽

Room Temperature ◽

Plasma Source ◽

Threshold Current ◽

Rf Plasma ◽

Plan View ◽

Light Emitting ◽

Dislocation Densities ◽

Power Outputs ◽

P Type

ABSTRACTThe use of a nitrogen rf plasma source for p-type ZnSe grown by MBE, has allowed a variety of pn junction based devices to be realized. The pn junctions have been combined with (Zn,Cd)Se quantum wells to implement semiconductor injection lasers, operating in the blue/green portion of the spectrum, which were reported by 3M and the Brown/Purdue group in the summer of 1991. In the past year the field has moved rapidly. In particular, we can now report CW operation at low temperatures as well as pulsed operation at room temperature (490nm) using a Zn(S,Se)-based device configuration. Laser power output per facet for some designs is above 300 mW, and threshold current densities are as low as 1000A/cm 2 at room temperature. Lasing was demonstrated from devices grown on both p and n-type GaAs substrates. X-ray rocking curves of theII-VI regions exhibit FWHM values below 20 arcsec for specific samples. Dislocation densities are less than 105 cm−2, below the threshold of TEM plan view imaging. The blue LEDs provide power outputs in excess of 100μW while exhibiting external quantum efficiencies of 0.1% at room temperature.

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Deformation of a NI-AL-FE Gamma/Beta Alloy

MRS Proceedings ◽

10.1557/proc-133-567 ◽

1988 ◽

Vol 133 ◽

Cited By ~ 4

Author(s):

R. D. Field ◽

D. D. Krueger ◽

S. C. Huang

Keyword(s):

Room Temperature ◽

Tensile Tests ◽

Duplex Structure ◽

Orientation Relationships ◽

Slip Transfer ◽

Beta Alloy ◽

Dislocation Densities ◽

Melt Spun ◽

Melt Spun Ribbons ◽

Specific Orientation

ABSTRACTRoom temperature tensile tests were performed on annealed melt-spun ribbons of a 50Ni-20Al-30Fe alloy. The ribbons were found to possess a duplex structure consisting of fcc γ and B2 β grains and exhibited tensile elongations in excess of 10% while still maintaining good strength. The tested specimens were found to contain high dislocation densities in both the γ and β grains, with no indications of stress-induced martensite formation. Dislocation analysis revealed that the vast majority of dislocations in the β have <100> Burgers vectors; however, <111> dislocations were also observed. Slip transfer was often facilitated by specific orientation relationships between the γ and β grains.

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Dependence of Intergranular Fracture on Boundary Topography and Cohesion

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071193 ◽

1973 ◽

Vol 31 ◽

pp. 150-151

Author(s):

J. E. Doherty ◽

A. F. Giamei ◽

B. H. Kear ◽

C. W. Steinke

Keyword(s):

Grain Boundary ◽

Room Temperature ◽

Nickel Base Superalloy ◽

Boundary Shear ◽

Room Temperature Ductility ◽

Solid Solution Matrix ◽

Nickel Base ◽

Solution Matrix ◽

Different Levels ◽

Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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Hepatocyte Alterations in Guinea Pigs FED Polychlorinated Biphenyls (PCBs), Dibenzodioxins (PCDD), AND DIBENZOFURANS (PCDF)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053085 ◽

1982 ◽

Vol 40 ◽

pp. 56-57

Author(s):

J. N. Turner ◽

D. N. Collins

Keyword(s):

Guinea Pigs ◽

Room Temperature ◽

Dose Group ◽

Methyl Cellulose ◽

Uranyl Acetate ◽

Target Organ ◽

Office Building ◽

Lead Citrate ◽

Control Groups ◽

Cooling Fluid

A fire involving an electric service transformer and its cooling fluid, a mixture of PCBs and chlorinated benzenes, contaminated an office building with a fine soot. Chemical analysis showed PCDDs and PCDFs including the highly toxic tetra isomers. Guinea pigs were chosen as an experimental animal to test the soot's toxicity because of their sensitivity to these compounds, and the liver was examined because it is a target organ. The soot was suspended in 0.75% methyl cellulose and administered in a single dose by gavage at levels of 1,10,100, and 500mgm soot/kgm body weight. Each dose group was composed of 6 males and 6 females. Control groups included 12 (6 male, 6 female) animals fed activated carbon in methyl cellulose, 6 males fed methyl cellulose, and 16 males and 10 females untreated. The guinea pigs were sacrificed at 42 days by suffocation in CO2. Liver samples were immediately immersed and minced in 2% gluteraldehyde in cacadylate buffer at pH 7.4 and 4°C. After overnight fixation, samples were postfixed in 1% OsO4 in cacodylate for 1 hr at room temperature, embedded in epon, sectioned and stained with uranyl acetate and lead citrate.

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Domain Formation in Synthetic Quartz

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100064839 ◽

1971 ◽

Vol 29 ◽

pp. 156-157

Author(s):

Joseph J. Comer

Keyword(s):

Electron Beam ◽

Room Temperature ◽

Domain Formation ◽

Synthetic Quartz ◽

Transmission Electron ◽

Black Spots ◽

Diffraction Mode ◽

Domain Boundaries ◽

Kikuchi Lines ◽

Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

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A Liquid Nitrogen Cooled Stage for STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052237 ◽

1974 ◽

Vol 32 ◽

pp. 444-445

Author(s):

Louis T. Germinario

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Liquid Nitrogen ◽

Room Temperature ◽

Objective Lens ◽

Thermal Drift ◽

Specimen Holder ◽

Resolution Capability ◽

Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

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Cryogenic atomic force microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084570 ◽

1991 ◽

Vol 49 ◽

pp. 54-55

Author(s):

K. A. Fisher ◽

M. G. L. Gustafsson ◽

M. B. Shattuck ◽

J. Clarke

Keyword(s):

Room Temperature ◽

Rapid Freezing ◽

Cryogenic Temperatures ◽

Soft Or ◽

Electrically Conductive ◽

Force Microscopy ◽

Flexible Molecules ◽

Advantages And Disadvantages ◽

Atomic Force ◽

Chemical Perturbation

The atomic force microscope (AFM) is capable of imaging electrically conductive and non-conductive surfaces at atomic resolution. When used to image biological samples, however, lateral resolution is often limited to nanometer levels, due primarily to AFM tip/sample interactions. Several approaches to immobilize and stabilize soft or flexible molecules for AFM have been examined, notably, tethering coating, and freezing. Although each approach has its advantages and disadvantages, rapid freezing techniques have the special advantage of avoiding chemical perturbation, and minimizing physical disruption of the sample. Scanning with an AFM at cryogenic temperatures has the potential to image frozen biomolecules at high resolution. We have constructed a force microscope capable of operating immersed in liquid n-pentane and have tested its performance at room temperature with carbon and metal-coated samples, and at 143° K with uncoated ferritin and purple membrane (PM).

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Benzylamine Tartrate as an Organic Glass Substrate for Carbon Films by Evaporation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069417 ◽

1970 ◽

Vol 28 ◽

pp. 484-485

Author(s):

A. C. Faberge

Keyword(s):

Vapor Pressure ◽

Viscous Liquid ◽

Glass Substrate ◽

Room Temperature ◽

Carbon Film ◽

Carbon Films ◽

Organic Glass ◽

Spectroscopic Examination ◽

Polymeric Substrates

Benzylamine tartrate (m.p. 63°C) seems to be a better and more convenient substrate for making carbon films than any of those previously proposed. Using it in the manner described, it is easy consistently to make batches of specimen grids as open as 200 mesh with no broken squares, and without individual handling of the grids. Benzylamine tartrate (hereafter called B.T.) is a viscous liquid when molten, which sets to a glass. Unlike polymeric substrates it does not swell before dissolving; such swelling of the substrate seems to be a principal cause of breakage of carbon film. Mass spectroscopic examination indicates a vapor pressure less than 10−9 Torr at room temperature.

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