bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Thermal Annealing of Low-Energy P and B Implants in Silicon, Optimized by High Resolution X-Ray Diffraction
Authors: Klappe Jos G.E. , Bársony István , Woerlee Pierre H. , Ryan Tom W. , Alkemade P.
Published: April 2011

In this paper, low-energy (45 keV) implantations of phosphorous and boron into silicon were studied. A comparison of doping profiles, secondary defect formation, electrical activation and diode leakage was made between Rapid Thermal Annealing (RTA) and conventional furnace annealing. The samples were analysed by High-Resolution X-Ray Diffraction (HR-XRD), X-TEM, SIMS, spreading resistance (SRP) and sheet resistance measurements.

The non-destructive HR-XRD technique combined with the novel simulation software was a very useful tool for the defect characterisation and for the choice of the optimum annealing temperature. Furthermore estimations of electrically active dopant atoms were made with HR-XRD by measurement of the strain. With RTA a substitutional dopant concentration of a factor 2 to 4 higher than with furnace annealing can be obtained, for P and B respectively. Electrical measurements show that not all of the substitutional dopants are electrically active, however. Thus estimates of the electrically active dopant atoms with HR-XRD require further study. Furthermore it appeared that RTA was superior to furnace anneal for lowering sheet resistances, defect removal and dopant profile broadening. However, furnace anneal gave the best results for diode leakage currents. This indicates that RTA processing needs to be further refined or that combined RTA/furnace processes need to be developed.
Boron Doping using Proximity Rapid Thermal Diffusion from Spin-on-Dopants
Authors: Rastogi M. , Zagozdzon-Wosik W. , Romero-Borja F. , Heddleson J. M. , Beavers R. , Grabiec P. , Wood L. T.
Published: April 2011

Proximity rapid thermal diffusion (RTD) has been investigated as a doping technique for p-type boron doped junctions. The efficiency of RTD has been studied as a function of process variables (temperature, time, and ambient) and evaluated based on sheet resistance measurements, secondary ion mass spectroscopy (SIMS), spreading resistance (SR), and Fourier transmission infrared absorption (FTIR) in a spin-on-dopant source (SOD). The doping efficiency in source wafers is controlled by different mechanism than in processed wafers. Strong influence of dopant incorporation in the processed wafers on oxygen content in the diffusion ambient is observed especially at low diffusion temperatures.
A 3-Dimensional Temperature Uniformity Model for a Rapid Thermal Processing Furnace
Authors: Henda R. , Scheid E. , Bielle-Daspet D.
Published: April 2011

A fully three dimensional model has been developed for simulating the thermal behaviour of a RTP furnace. This model consists of two components to achieve the whole analysis. The first component models the radiation heat flux density at the wafer surface as a function of the system geometry, the lamp position and intensity, and the wall reflectivities. The second component solves the heat conduction equation at each point within the wafer using appropriate boundary conditions, including convective cooling which effect depends on the process conditions. A particular attempt is made upon the achievement of a flat temperature profile over the wafer by investigating the system parameters in order to improve the RTP equipement.
Temperature dependent Emissivity Measurements of Si, SiO2/Si, and HgCdTe
Authors: Ravindra N.M. , Tong F.M. , Kosonocky W.F. , Markham J.R. , Liu S. , Kinsella K.
Published: April 2011

The results of emissivity of (a) Si and SiO2 /Si in the temperature range of 320 to 1240 K and (b). HgCdTe at temperatures of 303 and 440 K, using Fourier Transform Infrared(FTIR) spectroscopy, in the wavelength range of 1.5 to 20 μm, have been reported here. The measurements on SiO2 /Si have been performed for oxide thickness ranging from 60 to 500 nm. These results coufled with calculations of emissivity from first principles lead us to model the wavelength dependence of emissivity. Emissivity estimates have been obtained for HgCdTe using its fundamental optical constants.
Recent Pollution Prevention Research In III-V Device Manufacturing At Hewlett-Packard
Authors: Shire Douglas B.
Published: April 2011

Several coordinated hazardous waste minimization projects have been undertaken at our facilities involved in III-V device manufacturing. These include modifications to existing processes to reduce or eliminate emissions of CFCs, 1,1,1-TCA, xylenes, ethylene glycol ethers, 1,2,4-trichlorobenzene (in photoresist stripper), and other compounds. These issues are addressed in turn, noting the unique aspects of GaAs and GaP device manufacture that need to be taken into account. Goals achieved have been complete cessation of CFC and 1,1,1-TCA use and 33% reductions in xylene and 1,2,4-trichlorobenzene usage since 1990, despite significant increases in total production volume during the same time period. Specific strategies are also described for tracking chemical use and sharing best practices for hazardous waste reduction across functional groups.
Reactive Ion Etch of GaAs and AIGaAs Using BCl3, SiCl4 and SF6.Instead of CCl2F2
Authors: Wu J. W. , Chang C. Y. , Lin K. C. , Chang E. Y. , Hwang J. H.
Published: April 2011

In the past, CCl2F2 had been widely used in the dry etching process of the GaAs-based materials, However, it causes ozone depletion and is detrimental to the environment. In order to prevent further ozone depletion, it is necessary to search for some substitutedl gases. In this study, chloric gases, like BCl3 and SiCl4, were used to provide an alternative way for the reactive ion etch of GaAs and AlGaAs. To provide high etching selectivity between GaAs and AlGaAs, a fluorine containing gas SF6 is added, to increase the etch rate of GaAs than that of AlGaAs, which is due to the formation of non-volatile solid AlF3. In this study the etching characteristics of the BCl3/SF6, SiCl4/SF6 were studied and high etching selectivity between AlGaAs/GaAs is achieved.
Environmental Applications of Xanes: Speciation of Tc In Cement After Chemical Treatment and Se After Bacterial Uptake
Authors: Shuh D. K. , Kaltsoyannis N. , Bucher J. J. , Edelstein N. M. , Clark S. B. , Nitsche H. , Almahamid I. , Torretto P. , Lukens W. , Roberts K. , Yee B. C. , Carlson D. E. , Yee A. , Buchanan B. B. , Leighton T. , Yang W.-S. , Bryan J. C.
Published: April 2011

XANES (X-ray Absorption Near Edge Spectroscopy) has been employed to evaluate the efficacy of a process designed to encapsulate and reduce TcO4-in cement matrices, thereby immobilizing Tc. The oxidation state of Se following bioremediation of Se by bacteria has also been determined by XANES. The XANES measurements were performed at the Stanford Synchrotron Radiation Laboratory (SSRL) and the National Synchrotron Light Source (NSLS) at the respective K edges of Tc (21.0 keV) and Se (12.7 keV). Comparison of the XANES spectra of Tc in untreated cement to Tc in slag treated cement and to the chemical shifts of reference materials, shows that the oxidation state of Tc is the same in both cements. Thus, the addition of a reducing agent to the cement formulation does not significantly reduce the TcO4-. The common soil bacterium,Bacillus subtilis, is known to incorporate Se on or within the cell wall when exposed to a Se(IV) solution. The Se XANES spectra ofB. subtilis, as well as bacillus isolated from selenium rich soil, show that the organisms reduce selenite to the red allotrope of elemental Se.
Routes to Deagglomerated Nanopowder by Chemical
Synthesis
Authors: Burgard Detlef , Kropf Christian , Nass Rüdiger , Schmidt Helmut
Published: April 2011

The concept of tailored interfaces has been applied to the synthesis of
nano-scaled Y2O3/ZrO2 powders. The
microemulsion technique as well as the thermodynamically controlled growth
reaction have been utilized for this purpose. Both methods yielded
agglomerate free amorphous powders with particles sizes of 8 nm and 15 nm,
respectively. Cubic zirconia was obtained by calcination between 300 and 400
°C and crystallite coarsening was not observed. The calcined powders could
be redispersed by treating them with tertiary amines in aqueous
solutions.
Effect of Drying on Viscoelasticity and Permeability of
Gel
Authors: Scherer George W.
Published: April 2011

The beam-bending method was used to measure the effect of partial drying on
the viscoelastic relaxation behavior and permeability of a two-step
acid-base catalyzed silica gel. Both the elastic modulus
(E) and the permeability (D) showed a
power-law dependence on density (ρ): E ～
ρm, m ≈ 3.0; D ～
ρ-n, n ≈ 2.5. The viscosity of the network rose
from ～1011 to ～1013 Pa·s, and was strongly dependent
on age as well as density of the gel. The viscoelastic relaxation function
was well described by the stretched exponential function with an exponent of
0.3–0.5.
Controlling the Properties of Bulk Metal Oxides at a Molecular
Level: Alkoxides Vs Carboxylates‐Alkoxides Routes
Authors: Hubert‐pfalzgraf Liliane G. , Daniele Stephane , Boulmaaz Souad , Papiernik Renee
Published: April 2011

The reactions between alkoxides and/or alkoxides and anhydrous acetates have
been investigated for access to advanced multicomponent niobates or
titanates and with the aim to get insight into relationships between the
nature of the initial precursors ‐ single or mixed‐metal derivatives,
ligands (OAc or OR, R = Et, iPr),…‐ and the properties of the final
material. Data are based on a variety of techniques: FT‐IR, multinuclear NMR
(1H, 13C, 207Pb, 113Cd),
X‐ray investigations on single crystals. Powders have been analyzed by TGA,
SEM‐EDX, light scattering and XRD.
Tga and Dta Studies of Solvent-Exchanged Gels
Authors: Leeb Kurt , Durakpasa Hildrun , Breiter Manfred W.
Published: April 2011

Sols were prepared in the system TMOS:H2O:SOLV:HC1 with molar
ratios of 1:4:3:0.0005 for SOLV = MeOH, EtOH and DMF. The gelation and aging
of these sols took place in cuvettes covered by parafilm. The gels were
removed from the cuvettes 14 days after gelation. Solvent exchange was
carried out in each of the three solvents for a period of 14 days. Starting
with fresh solvent, the exchange was repeated three times.

TGA and DTA curves were taken with pieces of the original gels and of gels
after the 2nd and 3rd solvent exchange. The TGA curves display a
considerable weight loss in the temperature range of solvent evaporation. A
small step is observed at higher temperatures if MeOH or EtOH represent the
exchange solvent. The DTA curves allow a distinction what mixtures of
solvents are present. The effectiveness of the solvent exchange can be
evaluated.
Effects of Rare Earth Incorporation on the Ferroelectric and
Dielectric Properties of Sol-Gel Derived PbTiO3
Films
Authors: Teowee G. , Baertlein C.D. , Schlegel S.A. , Boulton J.M. , Uhlmann D.R.
Published: April 2011

Ferroelectric (FE) films, especially PZT films, have received increasing
attention for microelectronics applications such as FE memory and in high
density DRAM's. While rare earth doped PbTiO3 ceramics has been
studied for SAW and piezoelectric applications, rare earth-doped films
seldom have been systematically explored. A series of sol-gel derived
PbTiO3 films with varying amounts (5-15 mole %) of rare earths
(such as, Nd, Sm, Tb, Dy, Er ,Yb and La ) have been prepared using acetates
and alkoxides as precursors. The solutions were spin coated onto platinized
Si wafers. The effects of the type and amount of rare incorporation on the
phase assembly and microstructure have been quantified. The results of
dielectric characterization (e.g., dielectric constant, dissipation factor
and leakage currents) and FE behaviors (viz remanent polarization, and
coercive field) are presented; these films exhibited low leakage currents
(3E-10 A/cm2) and much higher dielectric constant (up to 525)
compared to undoped PbTiO3 films.
Preparation of Ceramic Composites by
Active-Ftller-Controlled-Polymer-Pyrolysis
Authors: Colombo Paolo , Abdirashid Mohamed O. , Guglielmi Massimo , Esposti Luca Mancinelli Degli , Agostini Luca
Published: April 2011

Active-filler-controlled-polymer-pyrolysis has recently been reported as a
novel processing route for preparing near-net shape bulk ceramic composite
materials. Active fillers, like Ti or Si powders, may react with solid or
gaseous decomposition products of the polymer or with the heating gas
atmosphere. In this study, a mixture of silicone resin (GE SR350) and Si
powder was heated at temperatures up to 1430°C in Ar or N2. After
the highest temperature firing, the resulting material was primarily
comprised of SiC and SiOC when the heating was performed in Ar, or of SiOC,
SiC, Si3N4 and Si2N2O when the
heating was performed in N2. The evolution of the microstructure
of the ceramic composite was followed by DTA-TGA, FT-IR and XRD.
The Incorporation and Thermal Stability of Organic Dyes in
Dialkylsiloxane-Oxide Matrices
Authors: Darabi John G. , Schmidt W. R. , Schwenke G. , MacCrone R. K.
Published: April 2011

The dyes oxazine 725, 7-acetoxy-4-methyl coumarin,
O-4-methylcoumarinyl-N-[3-(triethoxysilyl)-propyl] carbamate and
2′,7′-dichlorofluorescein were introduced during the acid-catalyzed
cohydrolysis of various molar ratios of tetraethoxysilane (TEOS) and the gel
modifers, diethoxydimethylsilane (DEDMS) or diethoxymethylvinylsilane
(DEMVS). The morphological features and optical absorption spectra of the
resulting dye doped gels were followed during subsequent drying and heating.
For DEDMS-TEOS molar ratios less than 1.375, gel cracking during drying was
a problem. DEDMS-TEOS molar ratios greater than 2.750 yielded optically
transparent monoliths, but did not allow for sufficient incorporation of dye
to be useful. However, the functionalized dye,
0-4-methylcoumarinyl-N-[3-(triethoxysilyl)-propyl] carbamate, appeared to be
significantly more soluble in such a highly modified matrix. Compared to
matrices derived from pure TEOS the DEDMS or DEMVS modified matrices
provided oxazine 725 doped with improved thermal stabilities. Finally, the
2′,7′-dichlorofluorescein doped dimethylsiloxane-oxide matrix showed good
thermal stability in its optical properties, having significant optical
absorption and little change in the wavelength of the absorption maximum
after heating to 300°C.
Microstructure and Crystallization Behavior of Sol-Gel Prepared
BaTiO3 Thin Films
Authors: Gust M.C. , Momoda L.A. , Mecartney M.L.
Published: April 2011

Thin films of BaTiO3 were prepared by the sol-gel route using
barium titanium methoxypropoxide in methoxypropanol. Sols with water of
hydrolysis varying between h=0 and h=2 were spun onto (100) Si and Ge coated
(100) Si substrates. XRD and analytical TEM were used to study the
microstructure and crystallization behavior of these films. Polycrystalline
BaTiO3 was obtained by heat treating the films at temperatures
between 600 and 750°C using either conventional furnace annealing or rapid
thermal annealing. Films prepared from sols having the highest water content
tended to crystallize first. The BaTiO3 thin films exhibited a
fine grain size on the order of 25–50 nm. No preferred orientation was
observed. The effects of the hydrolysis conditions of the sol, the type of
heat treatment, and the choice of substrate on the final microstructure of
the films are discussed.
Electron Microscope Study of Revolving Crystal Growth of Ý–Type
Vanadium Oxide Hydrate Under Hydrothermal Conditions
Authors: Kittaka S. , Miyahara H. , Yokota Y.
Published: April 2011

Anomalous revolving stacking crystal growth of β-type vanadium oxide hydrate
formed by hydrothermal treatment was studied by transmission electron
microscopy.
Retention Behaviours Of Carbon In Sol-Gel Derived
ZrO2 Studied By Fourier Transform Infrared
Spectroscopy
Authors: Zeng H.C.
Published: April 2011

The carbon retention patterns based on evolution of FT-IR spectra at
different calcination temperatures for ZrO2 gels derived from
Zr-n-propoxide-acetylacetone-water-isopropanol system are examined in
detail. For most captured carbon species, carbon can be depleted at
relatively low temperature of about 400°C. However, for lattice-included
species, especially those incorporated into lattice during phase transition,
a temperature around 900°C is needed to eliminate carbon in the gels. It is
found that water treatment alone does not provide new routes for carbon
retention in as-prepared ZrO2 gels. When gels are pre-treated
with Ni2+ and water, new forms of carbon containing species can
be observed. This is attributed to an inter-diffusion of Ni2+ and
ZrO2 matrix and the catalytic effect of resultant solid
solution NiO-ZrO2 on the retained carbon.
Rare-Earth Doped, Low Hydroxyl Organically Modified
Silicates
Authors: Yuh Soon-ku , Bescher Eric P. , Babonneau Florence , Mackenzie John D.
Published: April 2011

Low-hydroxyl organically modified silicates (ORMOSILS) were fabricated by a
non-hydrolytic reaction between methyl-modified silicon halides and tertiary
butyl alcohol under controlled atmosphere. The gels were characterized by
DTA and TGA., FTIR, 1H NMR and 29Si NMR. The solutions
were doped with anhydrous Erl3, which was dissolved in the sol
prior to gelation. Er3+luminescence in the gels was observed at
570 nm under excitation at 488 nm.
Nanoporosity in Ceramics from Polymeric
Precursors
Authors: Reid A.W. , Rand B. , Emsley R.J.P.
Published: April 2011

It is shown that ceramics derived from polycarbosilane polymers may develop
an open nanoporous network after heat treatment to a temperatures between
1300 and 1550°C in argon. The resulting SiC-based ceramics were
characterised by N2 gas adsorption analysis and X-ray
diffraction. The apparent surface area, and pore volume increase with
increasing heat treatment temperature, reaching values of 170
m2g-1 and 0.12 cm3-1 respectively. The
pore network develops as the SiC crystals grow and as carbon is ejected from
the structure. It is thought that the porosity may reside within the carbon
phase, but this remains to be confirmed.
Mobility Range in Hybrid Materials
Authors: Judeinstein P. , Brik M. E. , Bayle J. P. , Courtieu J. , Rault J.
Published: April 2011

The dynamical properties of hybrid materials obtained from mixtures of
silicon alkoxides and polyethers are studied. Different techniques are used
to analyze the mobility of the different parts of the material: thermal
analysis (DSC, DTMA) and NMR to probe the collective motion modes and EPR to
probe the local scale. The motions are dependent on the organic ratio in the
blend and the covalent grafting between the two phases. Some structural
models of these blends are proposed.
Relationships Between the Structure and the Surface Activity of
Nano-Sized Alumina in Acid Catalysis
Authors: Coster D. , Gruver V. , Blumenfeld A. , Fripiat J. J.
Published: April 2011

As shown in another communication to Symposium V, nano-sized aluminas
enriched in pentacoordinated aluminum (Alv) are obtained through
the limited hydrolysis of aluminum alkoxides. Here the surface properties of
these aluminas are investigated from the catalytic point of view. The goal
is to obtain geometrical information on the Lewis acid sites.
1H→27A1 (cross-polarization) high resolution MAS
NMR, using chemisorbed NH3 which acts as a XH spin
reservoir, allows the direct observation of surface Al involved in the
catalytic site. The polarization transfer from these protons to surface Al
is remarkably efficient because of the relatively short A1:N-H distance. It
is observed that the main Lewis acid sites are located on distorted
tetrahedral aluminum and pentacoordinated Al. These results are compared to
low temperature infrared data of adsorbed CO.
Stoichiometrically Controlled Solid State Synthesis and Crystal Growth of C60H2
Authors: Morosin B. , Jacobs Joshua , Henderson Craig , Schirber James E.
Published: April 2011

We have demonstrated the direct solid state synthesis of C60H2 by controlling the amount of hydrogen introduced into the reaction with C60. Palladium hydride has been used as the source of hydrogen. The main product 1,2-C60H2 is the isomer previously predicted by computational studies to be the lowest in energy of the possible 23 isomers; in addition, small amounts of the thermodynamically most stable isomer of C60H2, 1,2,3,4-C60H2, has also been obtained. To determine structural parameters by x-ray diffraction, crystal growth from various solvents yielded complex solventcontaining crystals which were examined; however, the complex nature of these crystals have so far precluded detailed crystal structure determinations.
Fullerene/Tubule Based Hollow Carbon Nano-Gears
Authors: Robertson D.H. , Dunlap B.I. , Brenner D.W. , Mintmire J.W. , White C.T.
Published: April 2011

We report the design of several symmetric star-shaped closed carbon cages using ball and stick models. Despite the presence of seven- and eight-membered rings, these hollow carbon sprockets—containing less than 500 carbon atoms—are predicted to be more energetically stable than C60. Also, we show that these sprockets can be connected to capped fullerene tubules to form a nanostructure similar to a mechanical gear and shaft. In addition, using molecular dynamics and a reactive hydrocarbon potential, we show that these gears can be turned against each other at high angular velocities without large deformations. These nanogears illustrate some of the possible complex small structures that can be formed by inserting 5-, 7-, and 8-membered rings in an otherwise graphitic network. These nanogears also show surprisingly robust mechanical properties.
Graphene Nanotubule Cold Field Emission Electron Sources
Authors: Fishbine B. H. , Miglionico C. J. , Hackett K. E. , Hendricks K. J.
Published: April 2011

Buckytubes are considered for high current density cold field emitter array electron sources. They may provide more stable, higher-brightness emission than existing cold field emitter arrays.
Growth of Diamond Films Using C3F8AND H2in A New System
Authors: Huangfu Ping , Jin Zengsun , Lu Xianyi , Zou Guangtian , Xiao Huaxian , Chen Tianyi , Liu Mingkai
Published: April 2011

In the present study, the new system used C3F8and H2 as source gases. Filament-assisted chemical vapor deposition was utilized. Continuous diamond films were grown on the Si and Mo substrates without any surface pretreatment. The results of scanning electron microscopy, Raman spectroscopy, X-ray diffraction, and atomic force microscopy measurements indicate that the films deposited on the Mo substrates are of high quality. Homoepitaxial diamond films were grown on the high pressure synthetic single crystal diamond substrates. The results show that in our experimental conditions epitaxial films were easily grown on the (111) synthetic diamond substrates and sometimes epitaxial filmse also grown on the (100) synthetic diamond substrates.
Hydrogen and Halogen Bonding on The Diamond (100)2 × 1 Surface: An Ab Initio Study
Authors: Hukka Terttu I. , Pakkanen Tapani A. , D'evelyn Mark P.
Published: April 2011

This work addresses mechanistic issues in conventional and halogen-assisted diamond growth via ab initio molecular orbital calculations on hydrogenated and halogenated carbon clusters (C9H12Xi, X=H, F, or Cl; i=O, 1, or 2) as models of the dimer-reconstructed diamond (100)2× 1 surface. The dimer bond lengths (XC-CX, XC-C., C=C) and the C-X and C=C π bond energies have been determined along with the effects of lattice constraints. The calculations show that dimer bonds are longer in clusters where only the topmost carbon layer is allowed to relax and the remaining carbon atoms are constrained to lie at diamond lattice positions than in fully relaxed clusters. The calculations also predict that the first C-X bond strength is approximately the same in constrained and fully relaxed clusters and that the second C-X bond is distinctly weaker due to π bond formation, particularly in fully relaxed clusters. These results indicate that the π bond between dimer atoms on the clean (100)-(2× 1) surface is weakened considerably by the constraints imposed by the lattice but is quite important nonetheless.
Synthesis and Characterization of Nitrogen Containing Diamondlike Carbon Films made by ion Beam Deposition
Authors: Shiao Jeansong , Zorman Christian A. , Hoffman Richard W.
Published: April 2011

Hydrogenated and nonhydrogenated nitrogen containing diamondlike carbon films (NDLC including a-C:N and a-C:N:H) were made in a dual ion beam deposition system. The asdeposited films were characterized by Raman spectroscopy, Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERD). The compositional stability of the films at temperatures up to 550°C was examined in situ by both RBS and ERD using a heated sample stage in the scattering chamber. The addition of nitrogen altered the Raman parameters when compared with conventional DLC. At elevated temperatures, the a-C:N films do not suffer nitrogen loss; however, the a-C:N:H films undergo nitrogen and hydrogen loss at 400°C.
Hard High Density Carbon Thin Films for X-Ray Multilayer Optics
Authors: Pedulla Joseph , Bartos Axel , Deslattes Richard D.
Published: April 2011

Dual ion beam assisted deposition (DIBAD) techniques are known to produce high quality diamond-like carbon films. The reported extreme hardness and high thermal conductivity characteristics of these films have stimulated our investigation of their use as one component of multilayer x-ray optical elements. Non-crystalline carbon films were produced and were characterized by means of highly collimated x-ray refiectometry (λ = 0.154 nn), atomic force microscopy, and IR Raman spectroscopy techniques. They exhibit extreme smoothness at the surface and interface, near diamond density, high hardness, and high uniformity over areas of 0.58 x 10-4 m2. Multilayers have been constructed of this non-crystalline carbon interposed with high electron density materials that have exhibited very good x-ray and EUV optical characteristics at λ = 0.154 nm and at λ = 4.0 – 8.0 nm.
Processing, Structure, and Morphology of Graphitic Carbon Foams Produced from Anisotropic Pitch
Authors: Dutta D. , Hill Charles S. , Anderson David P.
Published: April 2011

In order to produce a three-dimensional interconected graphitic network, foams were produced from carbon fiber precursor pitch and processed similarly to high modulus carbon fibers. Uniform size distributions of open spherical cell graphitic carbon foams were produced by microcellular foam blowing of anisotropic pitch using homogeneous and heterogeneous nucleation. The widths of cell walls and ligaments were in the range of the diameters of pitch-based carbon fibers (7-10 μm) and possessed significant alignment of anisotropic pitch crystallites.
Microstructure and Strain in GaAs/AlGaAs MQW thin Films Bonded to Different Substrates by Eutectic Alloying
Authors: Lin C. H. , Kuo H. C. , Lu Y. , Shen H. , Pamulapati J. , Dutta M. , Cheng J. Y. , Ren F. , Kuo J. M.
Published: April 2011

Research of the strain effect on semiconductors and their heterostructures has generated increasing interests due to its important device applications. We have developed a eutectic bonding technique to create in-plane anisotropic strain in GaAs/AlGaAs multiple quantum well (MQW) thin films. MQW thin films grown on (100) GaAs substrates were bonded to (100) GaAs, (100) Si and Y-cut LiNbO3 submounts with a Au/Sn eutectic alloy. The bonding materials consist of Au/Sn multilayer (80 wt% Au and 20 wt% Sn; 0.95μm) with a Cr (500Å) adhesion layer. The bonding process was optimized by carefully choosing the annealing conditions. After bonding, the substrates of the MQWs were removed by wet chemical etching. The in-plane strain was induced in MQW thin film due to the different thermal expansion between the thin film and submount. The strain was characterized using X-ray rocking curve. The microstructures of bonding interfaces and MQW thin films were examined by scanning electron microscope(SEM) and cross-section transmission electron microscope (XTEM). This bonding technique can be used for many new device applications which take the advantage of in-plane strain, as well as for device integration.
Strain and Interdiffusion Profiles in Epitaxied AU/NI (100) Multilayers Deduced From X-Ray Diffraction Experiments
Authors: Gilles B. , Marty A.
Published: April 2011

Au(100)/Ni(100) periodic superlattices have been grown by the MBE technique specially for X-ray diffraction experiments. The nominal number of Ni planes deposited were 1.5, 2, 4 and 5 ML and the thickness of the gold layers was always 1.5 nm. The X-ray profiles have been simulated using a kinematical structure refinement program. The obtained strain profiles are in very good agreement with earlier HREM results. It is shown that a strong interdiffusion occurs during the growth.
Stress in Giant Magnetoresistive Ni66Fe16Co18/Ag Multilayer thin Films
Authors: Jarratt J.D. , Barnard J.A.
Published: April 2011

Thin film stress has been measured in (Ni66Fe16Co18 25 Å/Ag 50 Å) multilayer thin films that exhibit annealing-induced giant magnetoresistance (GMR) known as ‘discontinuous’ GMR1. This GMR results when NiFeCo layers are broken up into discontinuous ferromagnetic islands or platelets by immiscible Ag atom grain boundary diffusion normal to the film plane. As-deposited films display no GMR and are in compression. An MR value of 5 % with a relatively sharp profile can be induced in a ten bilayer sample annealed at 400°C for 15 min. Annealing generally results in a decrease in the as-deposited compressive stress and can result in tensile stress at high enough temperatures. Interestingly, at the annealing temperatures corresponding to the maximum induced GMR, there is a plateau in the otherwise monotonic decrease in compressive stress with increasing temperature.

Stress-temperature plots reveal a plateau in the stress value during the heating of a ten bilayer sample due to plastic deformation in the film via densification. Isothermal stress-time plots done on a single sample show increasing compressive stress relief after each successively higher temperature anneal. The stress was also measured in a single bilayer film with the same volume of film as in a ten bilayer sample but far fewer interfaces. High and low angle x-ray diffraction (HXRD, LXRD) was used to reveal the structural evolution with annealing. Magnetic (M-H) hysteresis measurements revealed increasing coercivity and decreasing induced as-deposited in-plane magnetic uniaxial anisotropy with annealing temperature.
In-Process Evaluation of Kinetic Energy of Sputter Depositing Atoms Using Multijunction Thermal Converters
Authors: Su Quanmin , Huang D. X. , Wuttig Manfred
Published: April 2011

The kinetic energy of Au atoms was evaluated during sputter deposition of Au films using a multijunction thermal convenor (MJTC). The elastic strain energy of the deposited film was simultaneously measured by a high resolution vibrating membrane technique. For the evaluation the flux of Au atoms was treated as an energy flux irradiating a membrane connected to an infinite heat sink. The steady state temperature rise of this membrane under irradiation was used to convert to the kinetic energy of the atomic flux of known deposition rate. The kinetic energy of the sputter depositing Au flux was determined to be in the range of 5 to 18 eV. Only a fraction of it, of the order of 10−4, is converted into mechanical energy manifesting itself as film stress. The results demonstrate the possibility of using MJTCs as kinetic energy monitors during thin film deposition.
Elastic, Transversely Isotropic Film Indented by a Punch; Application to Multilayered Thin Films
Authors: Stone D.S.
Published: April 2011

A model calculates the compliance of elastic contact between a punch and bilayer, the latter consisting of a transversely isotropic film on top of isotropic substrate. Used in data analysis, the model helps estimate the Young’s modulus of amorphous silicon (100±20 GPa) layers within amorphous silicon/aluminum multilayer composites deposited on silicon.
High Power Magnetostrictive Materials from Cryogenic Temperatures to 250 C
Authors: Clark Arthur E.
Published: April 2011

The rare earths, both in elemental form and in compounds, are widely known as possessing many extraordinary magnetic properties. In this paper, we focus on the huge magnetically induced displacements (magnetostrictions) based upon the element terbium. A proper balance of magnetic anisotropy and magnetostriction, plus a proper choice of crystal axes lead to materials which can switch large quantities of energy between the internal (magnetic) and external (mechanical) states with the application of small triggering magnetic fields. Power densities 2000 times those of conventional magnetostrictive materials and 10-20 times those of typical piezoceramics are available. These materials are particularly valuable for smart systems where large energy transduction is needed such as active structure stiffening and active vibration control.
Tem Study of Twinning and Magnetic Domains in Terfenol-D
Authors: Dooley Jennifer , Graef M. De
Published: April 2011

This paper reports the results of detailed TEM observations on [211] oriented single crystal samples of Terfenol-D. Domain structures are interpreted in terms of recent micromagnetic models developed by James and Kinderlehrer. Lorentz transmission electron microscopy was performed on a JOEL 120CX equipped with a low field objective lens. We also report for the first time energy-filtered magnetic domain images, recorded using a Gatan Imaging Filter on a JOEL 40000EX high resolution TEM. This observational mode allows for enhanced resolution and improved image contrast.
Pulsed Laser Deposition of ZnO Thin Films for Piezoelectric Applications
Authors: Donovan E.P. , Horwitz J.S. , Carosella C.A. , Auyeung R.C.Y. , Chrisey D.B. , Smits J.G.
Published: April 2011

Transparent, insulating ZnO thin films have been deposited in-situ by pulsed laser deposition (PLD) from sintered targets. Films were deposited on substrates of fused quartz, <0001> A12O3, polycrystalline and textured (111) Au, at several substrate deposition temperatures (TSubstrate ≤ 700° C) and background oxygen pressures (P ≤ 300 mTorr). Film structure, morphology and electrical properties were characterized by X-ray diffraction, Rutherford backscattering spectrometry, optical properties were characterized by infrared transmission and reflection, and electrical resistivity was measured normal to the films. Films were crystalline, phase pure, and c-axis oriented. ZnO films deposited onto fused quartz and <0001> sapphire showed x-ray rocking curve full width at half maxima of 5° and 0.34°, respectively. The structure of ZnO films deposited on (111) textured Au was sensitive to the degree of texturing in the Au. The resistivity of PLD ZnO films was 61-63 kΩcm which was a factor of three improvement over sputter deposited films. Deposition of Au by both PLD and IBAD showed a negative correlation between the crystalline texturing and film adherence.
Influence of Mn Additions on the Thermoelastic and Pseudoelastic Behaviour of Cu-Ai-Ni Alloys
Authors: Morris M.A. , Lipe T.
Published: April 2011

The transformation properties of Cu-Al-Ni alloys modified by the additions of boron and manganese have been interpreted by studying the reversibility and stability of the martensitic transformation as a function of heat treatment and of manganese concentration between 2 and 4 wt%. The alloy containing 2% Mn exhibits a lack of thermoelasticity due to a decrease of the degree of B2 order and supression of DO3 order during quenching and the increase of both types of order during annealing. From the determination of the activation energies responsible for the martensitic and reverse transformations, we have deduced that, in both cases, the kinetics of the transformation are controlled by an atomic jump at the interface between the two phases.
The Interactive Response of Sma Springs which Control the Position of Dampers in Personal Environments™
Authors: Thoma Paul E. , Ivshin Yefim , Schachner Kurt D.
Published: April 2011

Personal Environments™ is a Johnson Controls, Inc. system for the control of indoor office environments. In this system, four SMA coiled extension springs interact to control the position of two dampers. Two opposing SMA springs connected to one damper control the percentage of primary conditioned air entering the system, and two opposing SMA springs connected to the second damper control the percentage of room air reentering the system.

The interactive operation of the SMA springs is discussed and a model is presented on the interactive response of the SMA springs. The SMA spring transformation temperatures, force - strain relationship, and the experimentally measured interactive response to temperature are presented and discussed.
Intelligent Material Design Using Shape Memory Alloy
Authors: Furuya Yasiubumi
Published: April 2011

Recently, shape memory alloy(SMA) is regarded as one promising material element natively with intelligent functions. I introduce the fundamental design concept and several trials for developing intelligent(smart) materials and structures by using shape memory alloy. Moreover, I introduce our recent works and point out the necessity for developing fundamental techniques to realize the intelligent materials using SMA.
Thermal and X-Ray Diffraction Studies of Doped and Undoped Single Crystal and Polycrystalline BaTiO3
Authors: Carreiro L.G. , Marzik J.V. , Deb K.K
Published: April 2011

Calorimetric changes in a series of pure and doped single crystal and polycrystalline BaTiO3were studied using differential scanning calorimetry over the temperature range of-110°C to 200°BC. The dopants, oxides of niobium and iron were varied from 0.5 to 8 mole percent, and strontium was varied from 5 to 35 mole percent. Endotherms were observed corresponding to three crystallographic transitions. The highest observed thermal transition corresponds to a tetragonal to cubic crystallographic transition and is also associated with the Curie temperature in these materals. Two additional endothermic transitions were also observed, an intermediatetemperature orthorhombic to tetragonal transition, and a low-temperature rhombohedral to orthorhombic transition. The three dopants decreased the crystallographic transition temperatures and Curie temperature as the dopant concentration was increased. X-ray diffraction was used to identify phases present and to determine the extent of solid solution. It is expected that these materials will display improved infrared detection as well as opto-electronic properties.
Piezoelectric-Ceramic Cylinder Type Vibratory Gyroscope
Authors: Yoshida T.
Published: April 2011

A new equivalent circuit for the vibratory gyroscope and an analyzing and controlling method for the vibration mode axis of the vibrator have been studied. The vibrator of this gyroscope consists of a piezoelectric-ceramic cylinder. On its outer cylindrical surface, interdigital electrodes are formed. And these electrodes are used for poling, AC excitation as well as detection. In order to prevent some deviation of the performance of the gyroscope due to the adhesion process, these electrodes are directly printed on the cylinder surface.

By changing the electrodes pattern and making a groove on the surface of the vibrator, the vibration mode axis can be easily controlled. Optimum design suited for demanded specifications can then be obtained.
Mechanical Properties of a β Containing Ti-Al-Cr-Alloy at Ambient and Elevated Temperatures
Authors: Chen W. R. , Wang J. , Zhang B. , Wan X. , Chen W. J.
Published: April 2011

The mechanical properties of a β-containing Ti-Al-Cr alloy were investigated at ambient and elevated temperatures. The results show that the Ti-Al-Cr alloy containing the β phase has a very high tensile strength but a poor ductility at ambient temperature, and that higher ductility is obtained at high temperatures. The temperature dependence of mechanical properties is found to be sensitive to the strain rate during the test. Fractography shows that the fracture mode changes from fully brittle to ductile-brittle mixture with the increased temperature. All the results suggest that the triple-phased TiAl alloys (α2+β+γ) may have the combined mechanical properties of the dual-phased T13Al ((α2+β) and dual-phased TiAl (α2+γ) alloys.
Investigation of a New Type of Al3Ti-Based Ll2 Alloy With Second Phase Precipitation
Authors: Hu Gengxiang , Sun Jian , Weng Xiaojun , Li Tong , Chen Shipu
Published: April 2011

Since the L12 structured Al3Ti alloy exists only in a narrow compositional range, further alloying of the single phase Ll2 alloy to improve its property seems hardly successful. Developing two-phase or multiphase Al3Ti alloys may be an effective approach for strengthening and toughening. In this article, a new type of Al3Ti-based alloy which has a Ll2 matrix with precipitates of a second phase is reported. The quaternary alloys based on Al67Mn8Ti25, and modified with Nb additions, consist of an Ll2 matrix and DO22 second phase particles in the annealed state, but the second phase can be dissolved by solution treatment and precipitated during high temperature aging. Remarkable strenghtening and promising compressive ductility were exhibited by the experimental alloy. The influence of composition on the microstructure and properties of the alloys are reported also.
Structural Phase Stability of ThSb Under Pressure
Authors: Palanivel B. , Kalpana G. , Rajagopalan M.
Published: April 2011

The electronic structure and high pressure structural phase transition in thorium antimonide have been investigated using the tight binding LMTO method. We have calculated the total energies by reducing the cell volume for NaCl as well as CsCl structures using TBLMTO method. The total energy calculations reveal that ThSb undergoes a structural transition from NaCl to CsCl structure at 78 kbar. The calculated value of equilibrium cell volume and the cell volume at which phase transition occurs are found to have a good agreement with the experimental results.
Counteracting Effects of Boron and Hydrogen on Ductility In Ni3Al
Authors: Chaki T. K.
Published: April 2011

A minute amount of boron doping in polycrystalline Ni3Al can suppress embrit-tlement due to environmental moisture. However, B is ineffective in suppressing hydrogen embrittlement due to cathodic charging. A mechanism is proposed to explain this seemingly contradictory dichotomy. Grain boundaries in B-free Ni3Al contain crack-like microcavities, to the tips of which atomic hydrogen, generated by the reaction of moisture with Al, can diffuse and cause embrittlement. In B-doped Ni3Al interstitial B atoms interact with Ni atoms and reduce the strength of directional bonding between Ni and Al atoms, such that the atoms can relax easily to close up the microcavities, thereby reducing environmental embrittlement. In the presence of a large amount of hydrogen, introduced by cathodic charging, microcracks can be nucleated in B-doped Ni3Al by hydrogen-enhanced dislocation activity, and then hydrogen embrittlement can proceed by enhanced plasticity at the crack tips.
Deformation Behavior of An O + β0 Processed Ti-21 Ai-23Nb Alloy at High Temperatures
Authors: Seetharaman Venkat
Published: April 2011

A hot workability study was conducted on an orthorhombic Ti-21AI-23Nb alloy using isothermal, constant velocity compression tests, over the temperature range 900–1155°C and nominal strain rate range 0.001 to 1.0 s−1. Three different microstructures corresponding to (a) hot rolled and mill annealed, (b) β0 -heat treated, and (c) β0 solution treated and direct aged conditions were examined. These microstructures varied from a relatively coarse distribution of O-phase precipitates in a matrix of transformed βO to the metastable retained βO. Flow stress displayed a sharp dependence on temperature, strain rate and on the initial structure. While uniform plastic flow was obtained at high temperatures and for structures containing primary O, βO-heat treated structures led to pronounced flow softening. Strong yield point phenomena and serrated flow were observed in selected test conditions and for microstructures containing high volume fractions of metastable βO. These flow instabilities resulting from Luder band propagation and dynamic strain aging are interpreted in terms of dislocation interactions in supersaturated βO.
Mechanical Behavior and Oxidation Properties of Molybdenum-Modified Cr3Si/Cr5Si3 Intermetallics
Authors: Nazmy M. , Noseda C. , Sauthoff G. , Zeumer B. , Anton D.
Published: April 2011

A series of two-phase chromium silicide base intermetallics have been investigated with respect to creep behavior and oxidation resistance. The first results of these investigations are reported. Good oxidation resistance has been demonstrated in one composition, which was due to the formation of the protective vitrious SiO2 layer, while the chromium oxide layer is very helpful at the intermediate temperature range.
Pseudo-Twinning in A Deformed Nb-15Al-25Ti B2 Alloy
Authors: Yang S.-S. , Hou D.-H. , Shyue J. , Wheeler R. , Fraser H. L.
Published: April 2011

An alloy with nominal composition of Nb-15Al-25Ti (in at.%) has been developed for high temperature structural applications. This alloy exhibits a B2 ordered structure in the as-cast form [1]. In addition to dislocation slip, pseudo-twinning occurs in this B2 alloy when deformed in compression at room temperature at a strain rate of ∼ 10−4 sec−1 to 3% strain. The pseudo-twinning plane has been deduced to be the {112} planes, which is similar to that in twinning of bcc metals. The mechanism of deformation pseudo-twinning in this B2 alloy is found to be analogous to the normal twinning mechanism in bcc metals, involving glide of partial dislocations with Burgers vector (b) given by b=l/6<111= on {112} planes. This pseudo-twinning mechanism causes a phase transformation from the B2 to an ordered orthorhombic structure.
Stucture of 1/2<110> Dislocations In γ-Tial by High Resolution Tem and Embedded Atom Method Modelling
Authors: Simmons J. P. , Mills M. J. , Rao S. I.
Published: April 2011

High Resolution TEM (HRTEM) observations of a dislocation in γ-TiAl are compared directly with atomistic calculations of dislocation structures performed with atomistic potentials in order to obtain an estimate of the Complex Stacking Fault Energy (γcsf). A value of between 470 and 620 mJ/M2 was obtained. HRTEM observations are presented of a Ti-52AI sample, containing a dislocation with Burgers vector 1/2<110> and 60° line orientation. This image is matched against images simulated from the outputs of Embedded Atom Method (EAM) simulations, using potentials that were fit to bulk γ-TiAl properties. Two atomistic simulation methods were employed in order to give the range of values for γcsf. In the first of these methods, three EAM potentials were used to simulate the stress-free core structure. These were fit so as to produce three different values of γcsf, all other properties being roughly the same as the literature values for γ-TiAI. All of these potentials produced cores that were more extended than the experimental observation. Thus a value of 470 mJ/M2, being the highest value of γcsf obtainable for the EAM potentials, is reported as a low limit estimate of γcsf for γ-TiAl. An upper limit estimate of the value of γcsf was obtained by applying an external ‘Escaig’ stress that forced the Shockley partials to further constrict, simulating the effect of an increase in γcsf, The preliminary value calculated from this procedure was 620 mJ/M2.