bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary Analysis of the Masonry of the Hagia Sophia Basilica, Istanbul
Authors: Livingston Richard A. , Stutzman P.E. , Mark R. , Erdik M.
Published: March 2011

Specimens of brick and mortar taken from the Hagia Sophia Basilica in Istanbul, Turkey, are being analyzed as part of an investigation of the construction history and present state of structural stability of the building. The analysis, covering both chemical composition and physical properties, involves a suite of instrumental methods including quantitative X-ray diffraction, thermal analysis, and automated image analysis of polished sections under SEM. These conventional methods are being supplemented by neutron diffraction and neutron and Xray small angle scattering. Preliminary results suggest the presence of cementitious materials including plombierite and tetracalcium aluminum carbonate in the mortar as well as calcium carbonate. The mortar contains significant amount of brick dust and also large chunks of brick as coarse aggregate. Given the pozzolanic nature of brick dust, it is possible that the mortar is actually not a conventional carbonated lime material, but rather a proto-concrete. The type of masonry construction involving very wide mortar joints, comparable to the width of the bricks, suggests that the Byzantine architects took advantage of this property of the mortar. This sophisticated materials technology may help to explain how the Basilica was constructed in such a short time period, and also to allow us to understand and model subsequent structural problems, including major deformations of the main piers. Also, the feasibility of dating by radiocarbon and thermoluminescence methods is being investigated to determine which parts of the elaborate buttress system are the original Byzantine structure as opposed to later Ottoman additions.
Theophilus and the Composition of Medieval Glass
Authors: Freestone Ian C.
Published: March 2011

Current understanding of medieval glass composition is compared with the instructions for the preparation and use of glass outlined by Theophilus in the early twelfth century. The points are illustrated by analyses of glasses from a range of objects and locations. They include the Westminster Retable, the pavement at Cluny Cathedral, Romanesque Mosan enamels on copper, Abbey windows from San Vincenzo in Italy and early enamelled glass vessels which are likely to have been made in Venice.
Physical and Cultural Constraint of Innovation in the Late Prehistoric Metallurgy of Cerro Huaringa, Peru
Authors: Epstein Stephen M.
Published: March 2011

The arsenical copper smelting technology reconstructed from the archaeological record at the late prehistoric industrial site of Cerro Huaringa, Peru, remained unchanged for the six centuries preceding the Spanish Conquest. This lack of technological innovation is argued to be a result of the physical constraints imposed by a cultural commitment to human breath as the source of draft.
From Theophilus to C.S.Smith: Discovery of an Eleventh Century AD Bell-Casting Mold From Venosa (Southern Italy)
Authors: Vidale M. , Vaccaro A. Melucco , Salvatore M.R. , Micheli M. , Balista C.
Published: March 2011

The recent discovery and excavation of the remains of a well preserved mold for bell-casting below the floor of the medieval church of the SS. Trinita′ of Venosa (southern Italy) provides a singular opportunity to reconstruct aspects of ancient bell-making technology and to compare the new archaeological data with the textual evidence on the same subject written by the famous monk Theophilus in the XIth chapter of his treatise “De Diversis Artibus”. Stratigraphical excavation and video-endoscopic inspection of the mold's interior allowed a preliminary reconstruction of the structure and use of this unique craft installation.
Restoration of Antique Church Bells: A Case Study
Authors: Ramos G. , Castro M.C. , Amadevilla I. , Gonzalez-Tirado C. , Castano V.M.
Published: March 2011

A 17th century bell, from Santuario-Mapethe (Mexico) was restored by using welding techniques. The work included the acoustical characterization of the bell before and after the actual welding as well as the analysis of the composition of the alloy originally employed, so a material as similar as possible to the original would be employed for the restoration. The advantages and disadvantages of the methods are discussed.
A Basic Study of Use-Wear “Polish” on Early Rice Paddy Farming Tools
Authors: Yamada Shoh
Published: March 2011

The analysis of use-wear “polish” variation and differences according to rock types contributes to the study of the “polish” formation process. The examination of the polished surface on andesite, rhyolite and a hard variety of slate with the SEM and optical light microscope thows that the polished surfaces are produced by mild wear. This provides a basis for use-wear analysis of stone farming tools made of these rocks, which come from early Japanese rice paddy cultivation contexts.
Analysis of Medieval Fresco Pigments From the Georgian Republic
Authors: Dneprovskaya Marie
Published: March 2011

The mineral composition of pigments from mural paintings of the 12th and 13th centuries in the grotto monasteries of Bertubani and Udabno (David-Caredga) were investigated. Apart from traditional pigments, many examples of brown-black plattnerite (PbO2) were found. They were generated by bacteriological oxidation of white lead. This oxidation process has caused great damage to the original painting color. It is necessary to investigate and to remember the potential influence of bacteria on painting pigments while conducting conservation and restoration as well as art historical analysis.
The Use of Epoxy Resins in Field Projects for Stone Stabilization
Authors: Selwitz Charles M.
Published: March 2011

The direct application of epoxy resins to deteriorating stone often encounters problems of penetration and color formation. Conservation scientists have worked around these problems by using organic solvents as carriers and have successfully consolidated stone with epoxy resins in a large number of projects. Work in Poland, Czechoslovakia, Italy and the United States is described. In Europe the methodology has evolved to treat objects of moderate size and isolated parts of buildings while in the United States procedures have been developed for stabilizing large portions of major buildings.
Microstructures of B72 Acrylic Resin/Mtmos Composites
Authors: Wheeler George Segan , Wolkow Eugene , Gafney Harry
Published: March 2011

Gels prepared from solutions of B72 acrylic resin and methyltrimethoxysilane (MTMOS) are examined by SEM. Four initial mixtures - 0,2,5 and 10% w/v B72/MTMOS - produced gels whose fractured surfaces exhibit distinct features. Scanning electron microscopy shows that neat MTMOS produces a glass-like gel while the addition of B72 creates MTMOS-derived spheres in a “connective tissue” of acrylic resin. These particle sphere/acrylic resin solids are mechanically weak composites.
Technical Evidence for Temporal Placement: Sculpted Adobe Friezes of Chan Chan, Peru
Authors: Pillsbury Joanne
Published: March 2011

Recent research on the technical aspects of the architectural reliefs at the site of Chan Chan, Peru, has yielded new evidence with which to assess conflicting relative sequences for the monumental compounds of the imperial city.
Molecular Dynamics Simulations of Low-Energy Atom-Surface Interactions
Authors: Sprague J. A. , Gilmore C. M.
Published: March 2011

Molecular dynamics simulations of the deposition of atoms on crystalline surfaces have been conducted using the embedded atom method. The following atom-substrate combinations have been employed: 0.1 - 40 eV Ag deposited on (111) and (100) Ag substrates; 0.1 eV Ag deposited on (100) Cu; and 0.1 eV Cu deposited on (100) Ag. The purpose of the calculations for Ag atoms deposited on Ag substrates was to investigate the effects of adatom arrival energy and substrate orientation on the interactions of low-energy atoms with crystal surfaces. The goal of tile Ag oil Cu and Cu on Ag calculations was to observe the mechanisms producing thepreviously-reported asymmetry in epitaxy for these systems. The Ag on Ag deposition simulations demonstrated that the effects of increased atom arrival energies in promoting layerby- layer film growth and producing diffuse substrate-filn interfaces (mixing) were basically the same on the (100) and (111) surfaces. At 0. 1 eV, representative of thennal evaporation, the degree of island formation on the (100) substrate was essentially tile same as previously reported for a (111) Ag substrate. At a given atom arrival energy between 10 and 40 eV, both the redistribution into full monolayers and the mixing by surface exchange interactions were seen to occur more readily on the close-packed (111) growth surface than on the more open (100) surface. The mixing was a stronger function of crystallographic orientation. Cu was observed to grow on (100) Ag as a (100)-oriented film, with the initial film layers transfonned essentially to the bcc structure by a Bain distortion, in agreement with various experimental results. The distortion of the film layers resulted in large-amplitude soft-mode (low-frequency) lattice vibrations. Ag was observed to grow on (100) Cu as a (111)-oriented film, as experimentally observed, with the <110>-type orientations of film and substrate parallel, as predicted by previous calculations of interfacial energy.
Characterization of Ti Alloys Bombarded by keV Deuterium Ions
Authors: Chambers G.P. , Hubler G. K. , Sprague J.A. , Grabowski K.S.
Published: March 2011

Thin Ti films have been bombarded at room temperature with 350–500 eV deuterium ions at current densities up to 0.5 mA/cm2. Analysis using scanning electron microscopy, x-ray diffraction, transmission electron microscopy, and secondary ion mass spectroscopy were carried out before and after bombardment. It was determined that deuterium diffuses rapidly throughout the Ti film, that the films were in a state of high compressive stress, and that the TiD2 phase was formed. No evidence of deuterium gas bubbles was found.
Epitaxial Growth of ZnTe and ZnSe on GaAs by Pulsed Laser Deposition
Authors: Rajakarunanayake Y. , Luo Y. , Aydinli A. , Lavalle N , Compaan A.
Published: March 2011

We report the successful growth of ZnTe and ZnSe epitaxial layers on GaAs by pulsed laser deposition. A frequency doubled Nd:YAG laser was used to ablate/evaporate II-VI bulk targets and pressed powder targets in an ultra high vacuum enclosure. For typical growth temperatures in the range 200°-400°C x-ray analysis of the layers revealed sharp <100> peaks with no evidence of growth in other orientations. Polarization dependent Raman spectroscopy was also used to further characterize the epitaxial layers, by verifying the selection rules for backscattering from <100> oriented films. The low temperature photoluminescence spectra show distinct near-band-edge features indicating high crystalline quality. The photoluminescence of the films grown from bulk targets was superior to that of films grown from pressed powder targets, indicating that the use of high purity bulk targets is critical. Our results indicate that pulsed laser deposition is a promising new growth technique for the fabrication of II-VI epitaxial layers with unique advantages.
Pulsed Laser Deposition of CdTe, HgCdTe, and β-SiC Thin Films on Silicon
Authors: Fenner D.B. , Li O. , Morrison P.W. , Cosgrove J. , Lynds L. , Johansson M.E. , Stoner B.R. , Glass J.T. , Xu Peirong , Zhang Hong
Published: March 2011

The successful methods for laser ablation and deposition of epitaxial thin films of metal oxides, especially the high-temperature superconductors (HTSC), have been adapted to pulsed laser deposition (PLD) of the narrow-band compound semiconductor HgCdTe, and the wide-band semiconductor β-SiC. Useful film quality is readily obtained in both cases: the HgCdTe films on CdTe wafers function in IR photodetection and the 3-SiC is epitaxial on both Si (100) and (111) wafers.
Ion-Beam Reactive Sputter Deposition of MgO Thin Films on Silicon and Sapphire Substrates
Authors: Chow Alice F. , Rou Shang Hsieh , Lichtenwalner Daniel J. , Auciello Orlando , Kingon Angus I.
Published: March 2011

MgO thin films were deposited on silicon and sapphire substrates using ion-beam reactive sputtering. Films have been analyzed using x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Highly oriented (100) MgO films have been obtained on Si (100) substrates. The in-plane orientation is predominantly [100]MgO//[100]Si, although a twist of up to ±10° between grains is observed. Epitaxial films of MgO were deposited on four different orientations of sapphire. The MgO film orientation was (111) on c-cut (0001) Al2O3 and exhibited double positioning boundaries in TEM analysis. On r-cut (1102) Al2O3, the MgO appeared to be oriented (730) with tilt and twist of ±2° between the grains. Epitaxial MgO films oriented (110) and (111) were obtained on m-cut (1010) and a-cut (1120) sapphire orientations, respectively. In-plane directions were extracted from TEM analysis on all the samples. Atomic force microscopy revealed fairly smooth MgO films on sapphire, varying from 0.35 nm average roughness for the MgO film on the m-cut substrate to 0.80 nm on the r-cut substrate.
Influence of Low-Dose Ion-Beam Mixing on CoSi2 Formation
Authors: Dehm Ikasko C. , Ryssel H.
Published: March 2011

In this study, the critical dose for ion-beam mixing of Co and Si with Ge-ions which results in homogenous CoSi2 formation after rapid thermal annealing was found. For this purpose, Co was deposited by sputtering on chemically cleaned, <100>-oriented Si and subsequently mixed with Ge ions at doses in the range of 2. 1014 to 1. 1015 cm−2. Silicidation was performed in a rapid thermal annealing (RTA) system at temperatures between 700° and 100°C. Rutherford backscattering measurements showed that annealing at 700°C results in an incomplete reaction when ion-beam mixing at a dose of 2.1014 cm−2 or no ion-beam mixing was performed. After annealing at 1000°C, TEM samples revealed an inhomogeneous CoSi2 film consisting of large grains embedded in the Si. Mixing at doses at or above 5.1014 cm−2 and subsequent RTA at 700°C resulted in uniform CoSi2 layers. Higher annealing temperatures cause larger grains and resistivity values as low as 18 μΩcm. Therefore, we demonstrated that the critical dose leading to complete formation of smooth CoSi2 films with abrupt interface is 5.1014 cm−2 which is nearly the same value as the amorphization dose of Ge in Si.
Modification of The Optical Properties of Al2O3 by Ion Implantation
Authors: White C. W. , Thomas D. K. , Zuhr R. A. , McCallum J. C. , Pogany A. , Haglund R. F. , Magruder R. H. , Yang L.
Published: March 2011

The implantation of Au into A1203 followed by thermal annealing at 1100°C leads to dramatic changes in the optical properties. The linear and nonlinear optical properties are correlated to the presence of small Au precipitates which form during annealing.
Crystallization Phenomenon Induced by Proton Beam Irradiation using Large Area Ion Implantation for Polycrystalline Silicon Thin Film Transistors
Authors: Yoshinouchi A. , Morita T. , Tsuchimoto S.
Published: March 2011

Crystallization induced by proton beam irradiation using large area ion implantation at low temperature (less than 600°C) have been investigated. Phosphine gas containing hydrogen of more than 95% is discharged by RF power of 100W. Both phosphorus ions and protons are accelerated by a potential of 100kV and implanted into polycrystalline silicon (poly-Si) layers. At a range of beyond 2×1015 ions/cm2 P1 ions dose, amorphous phase is primarily formed and then changes into polycrystals again and its grain sizes grow up to 50nm in average diameter. The crystallization is found to occur simultaneously with phosphorus doping and to depend on the amount of the irradiated protons. This technique enables us to eliminate the activation annealing process for implanted dopant.
Depth Dependence and Chemical Effects in Ion Mixing of Ni on SiO2
Authors: Banwell T. C. , Nicolet M.-A.
Published: March 2011

We report on our studies of Ni transport induced by 290 keV Xe irradiation of thin Ni films evaporated on thermally grown SiO2 at Xe fluences of 1015–1016 cm−2 and at temperatures of 77–750 K during irradiation. A simple etching technique was used to remove the free Ni leaving the SiO2 layer with incorporated Xe and Ni, whose profiles are directly measured using 2 MeV He+ backscattering spectrometry.

Marker experiments are used to verify the selectivity of the etching procedure. An apparent discontinuity in the Ni concentration across the Ni-SiO2 interface may produce the high selectivity observed within our etching process. Features associated with both cascade mixing and recoil implantation are readily discernible in the residual metal profiles. An exponential tail is evident beyond ∼ 500 Å of the SiO2 and is insensitive to temperature. within 500 Å of the surface the Ni profile demonstrates a strong temperature dependence which affects both the cascade mixing and recoil implantation processes. These profiles show favorable agreement with theory for samples implanted at temperatures of ≤ 300 K, while deviations in the high temperature behavior suggest a way chemical effects may alter the collision processes.
Amorphization of Garnet by Ion Implantation
Authors: Guzman A. M. , Yoshiie T. , Bauer C. L. , Kryder M. H.
Published: March 2011

Amorphization by ion implantation has been investigated in films of (SmYGdTm)3Ga0.4Fe4.6O12 garnet by transmission electron microscopy, incorporating a special cross-sectioning technique. These films were produced by liquid phase epitaxy on (111) garnet substrates and subsequently implanted with ions of deuterium at 60 keV and doses ranging from 0.50 to 4.5×1016 D2+/cm2 and ions of oxygen at 110 keV and doses ranging from 0.95 to 8.6×1014O+/cm2. The amorphization process proceeds in separate stages involving the formation of isolated amorphous regions, merging of these regions into a continuous band and subsequent propagation of the amorphous band toward the implanted surface. Details of these processes are interpreted in terms of various atomic displacement mechanisms.
Amorphous Phase Formation and Recrystallization in Ion-Implanted Silicides
Authors: Hewett C.A. , Suni I. , Lau S.S. , Hung L.S. , Scott D.M.
Published: March 2011

Ion implantation induced phase transformations and recrystallization during post-annealing in CoSi2, CrSi2, and Pd2Si are studied. All three silicides are found to reorder at about 1/3 the melting point of the silicide. We speculate that ion-implanted silicides recrystallize by the same mechanism and that amorphous phases produced by implantation are unstable rather than metastable.
High Current Density Implantation and Ion Beam Annealing in Si
Authors: Holland O. W. , Narayan J.
Published: March 2011

Annealing of amorphous layers in Si by high flux, selfion irradiation will be discussed. The mechanism for the lattice recovery is presented and related to the structure of the residual damage. It will be shown that highly supersaturated, alloyed regions, free from extended defects, result from the annealing process.
Formation of Oxide Layers by High Dose Implantation into Silicon
Authors: Gill S.S. , Wilson I. H.
Published: March 2011

Single crystal silicon was implanted with 80, 120, 160 and 240 keV oxygen ions. Rutherford backscattering (RBS) analysis was used to obtain the implanted oxygen profile and the oxygen to silicon ratio in the implanted layer for doses in the range 1016 to 1.5 × 1018 O2+ cm−2 for room temperature implants. The depth and the thickness of the buried oxide layer has been measured as a function of implantation energy and oxygen dose. Chemical formation of stoichiometric SiO2 was confirmed by infra-red (IR) spectroscopy. Both RBS and IR indicate that once a surface oxide layer is formed for very high dose levels, the layer thickness decreases with increasing implanted dose beyond a critical dose level.
Characterization of Ion Implanted Silicon by Spectroscopic Ellipsometry and Cross Section Transmission Electron Microscopy
Authors: Mcmarr P. J. , Vedam K. , Narayan J.
Published: March 2011

This paper deals with the application of spectroscopic ellipsometry (SE) and cross-section transmission electron microscopy (XTEM), to the characterization of damaged surface layers in ion implanted Si single crystal. Si samples of 2–6Ω·cm resistivity and <100> orientation were implanted with 28Si+ ions in the dose range of 1.0 × 1016–1.5 × 1016 ions/cm2 using ion energies of 100 and 200 keV. Ion current densities were varied from 6 to 200 μA/cm2. Depth profiles of the implanted samples were evaluated from the spectroscopic ellipsometry data. These calculated profiles were compared with the TEM micrographs of the cross sections of the samples. Excellent agreement is obtained between the two characterization techniques. The characteristics of the depth profiles of the samples, as established by the two techniques, is shown to be the result of annealing occuring during implantation.
Ion Implantation Damage in CdS Crystals Using RBS/Channeling and Tem
Authors: Parikh N.R. , Thompson D.A. , Burkova R. , Raghunathan V.S.
Published: March 2011

Implantation damage in single crystal of CdS produced by 60 keV Bi+ and 45 keV Ne+ at 50 K and at 300 K has been studied. Measurements of Cd disorder and dechanneling behaviour have been made by means of RBS/channeling for He ions ranging in incident energy from 1.0 to 2.8 MeV either along <0001> or <1120> axial channeling directions. The amount of disorder measured were two orders of magnitude lower than the calculated Cd disorder. Damage when analysed along the <0001> axis is larger than when analysed along the <1120> axis.Xmim values for the implanted crystals decreases as the EO increases, when analysed along <0001> direction. TEM observations of Bi implanted samples show that the dislocation loops of b = 1/3 <1120> are produced. Attempts have been made to correlate the RBS/channeling results with the defect strictures observed in microscopy.
A Channeling Study on Mg Implanted InSb Single Crystals
Authors: Alberts H.W.
Published: March 2011

Proton and α-particle channeling were used to study the radiation damage caused by the implantation of 160 keV Mg ions in InSb. The implantations took place at various substrate temperatures ranging from room temperature to temperatures just below the melting point and doses ranging from 5.1013 to 1.1016 Mg+ cm−2. The isochronal annealing of the room temperature implanted crystals started at 200°C and damage could not be completely removed even at temperatures just below the melting point. For crystals implanted at elevated substrate temperatures no annealing effects during implantation occured up to 400°C. Above 400°C a sharp reduction of damage indicates that the rate of formation of more complex defect configurations during the implantation process becomes smaller than the annihilation rate of the vacancy-interstitial pairs. A non-linear dependence exists between the degree of radiation damage in the InSb lattice and the implanted dose.
A Comparative Study of Near-Surface Effects Due to Very High Fluence H+ Implantation In Single Crystal FZ, CZ, and Web SI
Authors: Choyke W.J. , Irwin R.B. , Mcgruer J.N. , Townsend J.R. , Doyle N.J. , Hall B.O. , Spitznagel J.A. , Wood S.
Published: March 2011

Crystals of float-zone, Czochralski, and Web Si having widely differing oxygen concentrations were imrplanted at 300°K with large fluences of hydrogen. Experiments using RBS/channeling, profilometry and microscopy are reported. For room temperature implants the step-height h, the distribution of displaced atoms ND(x) and the total number of displaced atoms/cm2 (aD) are all essentially independent of the oxygen convent of the Si.
Damage Distribution Studies in Proton-Implanted GaAs
Authors: Jenkinson H. A. , O'Tooni M. , Zavada J. M. , Haar T. J. , Larson D. C.
Published: March 2011

Samples of n+-GaAs implanted with 300 keV protons have been examined using high resolution electron microscopy, capacitance-voltage profilometry, and infrared reflectance. In contrast to previously reported results, electron microscopic examination of the as-implanted samples revealed the presence of dislocation loops and/or precipitates both near the wafer surface and at the bottom of the implanted layer. These results are corroborated by electrical and optical measurements.
Behavior of Implanted α-Al2O3 in an Oxidizing Annealing Environment
Authors: Farlow G. C. , White C. W. , Mchargue C. J. , Appleton B. R.
Published: March 2011

The transition metal ions Fe, Mn, Ni, Ti, and Cr as well as the group III-A ion Ga were implanted in a random direction close to the c-axis of α-Al2O3 single crystals. These were subsequently annealed in flowing oxygen at temperatures between 600 and 1500°C. The impurity and damage distributions were determined by He backscattering and channeling techniques. The normally trivalent ions, Fe, Ga, and Cr show strong tendency to become incorporated into substitutional sites, whereas the normally divalent ions, Cu and Mn show no such tendency, even at high temperatures. Most of the impurities tend to move toward the surface with only Fe, Ga, and Cr showing tendency towards bulk diffusion. In all cases the Al sublattice recovers at lower temperatures than the oxygen sublattice.
Implantation-Induced Conductivity of Polymers
Authors: Wasserman B. , Braunstein G. , Dresselhaus M.S. , Wnek G.E.
Published: March 2011

Ion implantation causes an increase by ~14 orders of magnitude in the electricalconductivity of normally insulating polymers such as polyacrylonitrile (PAN), poly(2,6 dimethyl phenylene-oxide) (PPO), and poly (pphenylene sulfide) (PPS), after ion implantation with Br at fluences of 3 × 1015 ions/cm2. The temperature dependence of the dc conductivity was measured in the range 23 〈 T 〈 293 K and results show an exponential law σ ~ exp(−To/T)a) for PAN, PPO and PPS with α =1/2, suggesting a one-dimensional hopping mechanism. The temperature dependence of the thermoelectric power (TEP) identifies the sign of the dominant carrier type. The TEP exhibits linear metallic behavior, with small magnitudes (~3μV/K), and shows Br implantation to yield p-type material in PPS and n-type material in PAN with extremely low values of mobility (〈 10−3 cm2/V sec) and correspondingly very high values of the carrier concentration estimated to be 5 × 1022 cm-3. Results are also reported for the frequency dependence of the AC conductivity and of similarly implanted PPS and PAN samples.
Comparison of Conductivity Produced in Polymers and Carbon Films by Pyrolysis and High Energy Ion Irradiation
Authors: Venkatesan T. , Dynes R. C. , Wilkens B. , White A. E. , Gibson J. M. , Hamm R.
Published: March 2011

The electrical properties of pyrolyzed polymers have been studied recently.1,2 It has been shown that organic, polymeric3 and non-polymeric4 films can be made conductive (ρ ~ 10−3Ωcm) by ion beam irradiation. Common to all of the films was the presence of carbon as a constituent element and both pyrolysis and ion beam irradiation3 was shown to increase the relative carbon content of the films. The ion beam irradiated organic films 3,4 exhibited a temperature dependence of their resistivity of the form ρ(T) = ρ∞e−(TЛ)*, where ρ is the ion-induced resistivity, ρ∞ and T0 are constants and T is the temperature. At very high doses of irradiation (1017cm−2Ar+@ 2MeV) the film resistivity was temperature independent. Very similar transport properties were observed in the pyrolyzed polymers1 as well, though the lowest resistivities achieved were higher than the resistivity values observed in the ion irradiated3 polymer films. In both the pyrolysis and ion-irradiation experiments the temperature dependence has been explained by a model due to Sheng and Abeles,5 which involves charge transport by hopping between conducting islands embedded in an insulating matrix. Such striking similarities between two distinctly different modes of energy deposition in the films, prompted us to compare the effects of pyrolysis and ion irradiation in different carbon containing films. We compared both a polymer (HPR-204°) and a film of electron beam evaporated carbon film. While in the former case one would observe chemical degradation as well as structural modification, by studying pure carbon films the physical nature of the processes could be clarified. We report metallic carrier densities in both films and evidence for significant structural rearrangement. We conclude that pyrolysis and ion beam irradiation have similar effects on both polymer and carbon films.
Channeling Studies of Thermal Regrowth in Ion Damaged Graphite
Authors: Venkatesan T. , Elman B. S. , Braunstein G. , Dresselhaus M. S. , Dresselhaus G.
Published: March 2011

The crystallization of disordered surface layers on highly oriented pyrolytic graphite (HOPG) have been studied by Rutherford backscattering spectrometry (RBS) and channeling techniques. Disordered layers (~1000–3000Å thick) are produced on the surface of HOPG by the implantation of various ions. The disordered layers are regrown by thermal annealing of the samples in an inert environment. Isochronal anneals reveal two distinct regrowth processes: one, a rapid process of low activation energy (Ea ~ 0.15 eV) which is observed primarily in regions where the disorder is sufficient to prevent the channeling of the ions but insufficient to totally destroy the graphitic structure. This low activation energy may indicate annealing of the damage by migration of interstitials where the interstitials are the knock-on carbon atoms produced by the primary ions. A regrowth process with higher activation energy (Ea ~ 2.0 eV) occurs primarily in regions where the disorder is close to the saturation-disorder produced by ion implantation. Both the regrowth processes are epitaxial in nature and the epitaxial nature of the process may explain the much lower activation energy for 3D AB stacking as measured in ion implanted graphite when compared with results on the bulk graphitization of pyrocarbons.
High Temperature Implantation in Graphite
Authors: Braunstein G. , Elman B.S. , Dresselhaus M.S. , Dresselhaus G. , Venkatesan T.
Published: March 2011

In previous studies it was found that when highly oriented pyrolytic graphite (HOPG) is implanted at room temperature, the damage caused by the implantation could be completely annealed by heating the sample to temperatures higher than ∼ 2500°C. However at these high temperatures, the implanted species was found to diffuse out of the sample, as evidenced by the disappearance of the impurity peak in the Rutherford backscattering (RBS) spectrum. If, on the other hand, the HOPG crystal was held at a high temperature (≥ 600°C) during the implantation, partial annealing could be observed. The present work further shows that it is possible to anneal the radiation damage and simultaneously to retain the implants in the graphite lattice by means of high temperature implantation (Ti ≥ 450°C) followed by annealing at 2300°C.
Transport Properties and Electron Microscopy Studies of Ion Implanted Graphite
Authors: Chieu T.C. , Elman B.S. , Salamanca-Riba L. , Endo M. , Dresselhaus G.
Published: March 2011

Graphite fibers with high structural perfection and small diameters (∼1 μm) provide a sensitive medium to study the effect of ion implantation on the transport properties of graphite and to observe the defect structure associated with the implantation process. Graphite fibers prepared from the thermal decomposition of benzene and subsequent heat treatment to high temperatures (∼2900°C) have been shown to achieve the high structural perfection necessary to carry out such experiments. Implantation-induced changes in the fiber resistivity are reported and are found to be larger at low temperature, as expected on the basis of residual resistance arguments. Using the lattice fringe imaging technique of high resolution electron microscopy, the implantation-induced defect structure can be observed directly. The results show local expansion of the interlayer graphite planes, with an interlayer separation ranging up to 3.9 Å in the implanted region, compared with ∼3.4 Å for the well-ordered layers beyond the ion penetration depth.
Dynamic Recoil Mixing for the Production of Silicon Nitride Films
Authors: Kheyrandish H. , Colligon J.S. , Hill A.E.
Published: March 2011

In Dynamic Recoil Mixing (DRM) a film of constant thickness is sputtered on to a substrate by using a broad low energy (lkeV) ion beam and is subsequently bombarded by a high energy (10 key) ion beam. During the bombardment process a dynamic balance is maintained between the backsputtering and the deposition of the film, thus providing an ‘unlimited’ source of the dopant material. In this way very high surface dopant concentrations may be achieved which otherwise cannot be reached by more conventional ion beam mixing techniques. Furthermore, by choosing reactive ion species, films of novel chemical compositions may be produced. This technique has been employed to produce silicon nitride films on polished commercial mild steel samples. Measurements of knoop hardness of these films indicate an increase of over 200% whilst the wear and friction properties have shown considerable improvement. Conventionally sputtered silicon films of similar thickness, recoil mixed silicon using argon, or implantation of 10 keV argon and nitrogen to similar doses, indicate only a modest change in tribological characteristic compared to the reactive mixed films.
Structure of Al-N Films Deposited by a Quantitative Dual Ion Beam Process
Authors: Hentzell H.T.G. , Harper J.M.E. , Cuomo J.J.
Published: March 2011

We 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
Carrier Lifetime Reduction by Ion Implantation into Silicon
Authors: Mdgro-Campero A. , Love R.P.
Published: March 2011

Ion implantation is emerging as a versatile tool for the control of carrier lifetime in silicon. We present results on the use of argon and proton implantations to reduce lifetime. Particle energies used imply submicron penetration depths into the silicon. We find that within the first micrometer from the surface, the generation lifetime can be reduced by several orders of magnitude, and varies inversely with dose. A change in doping concentration was found only at the highest dose used (1014 cm−2). Effects of the implantations on surface generation velocity and oxide charges were also studied.
Effects of Ion Implantation on the Rolling Contact Fatigue of 440C Stainless Steel
Authors: Kustas F. M. , Misra M. S. , Sioshansi P.
Published: March 2011

Cylindrical 440C stainless steel specimens implanted with N and Ti were examined for their fatigue resistance and wear behavior by rolling contact fatigue (RCF) testing. The results obtained from RCF testing showed a 40% increase in the B-10 fatigue lifetime for N implanted and a 17% increase for Ti implanted 440C specimens compared to baseline, unimplanted 440C. Quantitative surface analysis by Auger Electron Spectroscopy (AES) was performed to determine the effects of process parameter optimization and ion beam masking on the elemental concentration profiles.
Dose Dependence of Ion Beam Mixing of Au on Amorphous and Single Crystalline Si and Ge
Authors: Poker D. B. , Holland O. W. , Appleton B. R.
Published: March 2011

The rate of ion induced mixing of 700 Å Au layers vapor deposited on amorphous and single crystalline Si substrates held at room temperature was measured as a function of dose using 300 key Si, 350 keV Ar, and 525 keV Kr ion beams.Mixing profiles were measured at various fluences by Rutherford backscattering techniques and were found to be consistent with mixed layers whose thicknesses increased with ion dose. Mixing compositions, which were stoichiometric over the entire mixed region at Au-28.5 at.% Si, were found to be independent of ion species or implant fluence. For all ion species the dose dependence of mixing was closer to linear than the square root power law reported previously [1]. In addition, the mixing rate for Au on single crystalline substrates was significantly higher than Au n substrates amorphised by Si (self-ion) implantation at liquid nitrogen temperature. No difference was found between the mixing rates when the amorphous substrates were prepared by room temperature implantation. Preliminary results indicate similar behavior for the Au/Ge couple.
Applications of Ion-Implanted Covalent Polymers
Authors: Weber David C. , Bernett Marianne K. , Ravner Harold
Published: March 2011

Materials presently used for packaging precision instrument bearings contain minor amounts of antistatic agents, shown earlier to be potential contaminants to both bearing surfaces and lubricants. One method to eliminate the antistatic additives is to use electroactive polymers. The materials with the most promise for this application are the F ion implanted polyacetylene and polyparaphenylene. The characteristics and behavior of the polymers will be presented.
Energy Dependence of Compound Growth in Au-Al and Cu-Al Bilayer Systems During Ion Beam Mixing
Authors: Campisano S.U. , Techang Chu , Cannavo ' S. , Rimini E.
Published: March 2011

The kineticsof phase formation and growth in Au-Al and Cu-Al thin film bilayers under ion beam bombardment was investigated in detail for the dependence on the beam energy. The experimental data can be interpreted within the radiation enhanced diffusion description, taking into proper account the target configuration, the growth of a new phase and the deposited energy density distribution.
Synthesis, Structure, and Characterization of La1−xBax (0 ≤ x ≤ 1)
Authors: Sunstrom Joseph E. , Kauzlarich Susan M.
Published: March 2011

The compounds La1−xBaxTiO3 (0 ≤ × ≤ 1) have been prepared by arc melting stoichiometric amounts of LaTiO3 and BaTiO3. Single phase samples can be made for the entire stoichiometry range. The polycrystalline samples have been characterized by thermal gravimetric analysis, X-ray powder diffraction, and temperature dependent magnetic susceptibility. This series of compounds has been studied as a possible candidate for an early transition metal superconductor.
New Group 2 Compounds Useful for Preparation of thin films of Electronic Ceramics
Authors: Rees William S. , Dippel Kerstin A. , Carris Michael W. , Caballero Celia R. , Moreno Debra A. , Hesse Werner
Published: March 2011

We have prepared examples of several new classes of group 2 compounds, including ether- and amine-substituted metallocenes, inter- and intra-molecular Lewis base stabilized bis(β-diketonates), and clam-shell oligioether bis(alkoxides), and investigated their use as potential sources in the preparation of ceramic materials from molecular precursors. Examinations have included vapor pressure measurements, hydrolytic, oxidative, thermal and photolytic stability, vapor phase, solution and solid state structures, and evaluation for potential CVD growth of thin films of electronic ceramics. Results to date indicate that intramolecular stabilization is more advantageous than intermolecular stabilization for achievement of optimal CVD source criteria, and that completion of the coordination sphere around the metal atom requires tuning of both ligand spatial and electronic requirements.
Reaction Kinetics for the Hydrolysis of Titanium Isopropoxide Carboxylate Complexes
Authors: Gagliardi Charles D. , Dunuwila Dilum , Van Vlierberge-Torgerson Beatrice A. , Berglund Kris A.
Published: March 2011

Titanium alkoxides modified by carboxylic acids have been widely studied as the molecular precursors to ceramic materials. These alkoxide complexes have also been very useful in the formation of stable, porous, optically clear films having many novel applications such as chemical sensors, catalytic supports, and ion-exchange media. To improve the processing of these materials, it is essential to better understand the kinetics of the chemical transformations which occur.

The kinetics of the hydrolysis reaction are studied for selected carboxylic acids using Raman spectroscopy to probe the chemistry of the process. The study has a special emphasis on the titanium isopropoxide-valeric acid system due to the superior quality of these films over other carboxylates. Greater knowledge of the hydrolysis kinetics allows increased control over the quality of the film materials and should be of general interest to those working with modified metal alkoxides.
Usaxs and X-Ray Microscopy Investigations on Silica and Precursors of Zeolites
Authors: Beelen Theo P. M. , Dokter Wim H. , van Garderen Harold F. , van Santen Rutger A. , Browne Mike T. , Morrison Graeme R.
Published: March 2011

Combination of SAXS and USAXS measurements provide an extended q-range (0.006–3.0 nm-1) to study fractal growth of both aging silica gel as well as precursors of zeolite-A. Mass (silica) and surface (zeolite) fractals are observed. Scanning transmission X-ray microscopy (STXM) proves to be an extremely useful technique to obtain direct images of wet samples in the 0.1–100 micron range, confirming the SAXS/USAXS results on even larger length scales.
New Chemistry for the Sol-Gel Process: Acetone as a New Condensation Reagent
Authors: Goel Subhash C. , Chiang Michael Y. , Gibbons Patrick C. , Buhro William E.
Published: March 2011

A nonhydrolytic sol-gel process that uses acetone as the condensation reagent is described. In the new process, the hydrocarbon soluble Zn(OCEt3)2 is converted to a rigid, transparent gel and then to ZnO by an aldol-condensation-elimination sequence. The chemical pathway for the transformation has been established, and differs completely from the pathway for the conventional hydrolytic sol-gel processing of alkoxide precursors. The new, nonhydrolytic strategy may prove applicable to a variety of metal-alkoxide systems.
Electrical Properties of Crystalline and Amorphous Pb(ZrxTi1−x)O3 Thin Films Prepared by the Sol-Gel Technique
Authors: Xu Yuhuan , Cheng Chih-Hsing , Xu Ren , Mackenzie John D.
Published: March 2011

Pb(ZrxTi1−x)O3 (PZT) solutions were prepared by reacting lead 2-ethylhexanoate with titanium n-propoxide and zirconium n-propoxide. Films were deposited on several kinds of metal substrate by dip-coating. Crystalline PZT films and amorphous PZT films were heat-treated for 1 hour at 650°C and at 400°C, respectively. Electrical properties including dielectric, pyroelectric and ferroelectric properties of both crystalline and amorphous PZT films were measured and compared. The amorphous PZT thin films exhibited ferroelectric-like behaviors.
Preparation of BaTiO3 and PbTiO3 thin Films on BaPb3 Substrates by the SOL-GEL Method and Their Properties
Authors: KuWabAra M. , Kuroda T. , Takahashi S. , Azuma T.
Published: March 2011

Barium titanate, lead titanate and barium-lead titanate thin films were prepared by the sol-gel method using metal alkoxides on metallic conducting BaPbO3 ceramic substrates. Thin films were deposited on the polished surfaces of the substrates by spin coating solutions containing Ba(OC2H4OCH3)2, Pb(OCOCH3)2 and Ti(O-iC3H7)4 and methoxyethanol. The gel films were then fired at appropriate temperatures to yield ceramic thin films. A 0.50 µm-thick BaTio3 film showed a dielectric constant of 280 and tan ° of 3% at 1kHz with no distinguishable peak of dielectric constant at any temperature between 20°C and 200°C. Both PbTiO3 (0.75 µm thick) and Ba0.7Pb0.3 (0.2 µm thick) films, on the other hand, showed a distinguishable peak of dielectric constant at their Curie point with a rather deformed P-E hysteresis loop at room temperature.
Growth of Oriented Tin Oxide Thin Films from an Organctin Compound by Spray Pyrolysisxf
Authors: Yag Isao , Kaneko Shoji
Published: March 2011

Tin oxide films were grown from di-n-butyltin diacetate on a heated glass substrate by a pneumatic spraying system The effects of various film growth parameters. i.e solvent, solution feed rate, film thickness, and film growth rate on the microstructures of the films were studied by X-ray diffraction and scanning electron microscopy The SnO2 films of the (200) plane were grown by the optimum growth parameters
Laser Densification of Sol-Gel Derived TiO2 - Thin Films.
Authors: Arfsten N. , Lintner B. , Heming M. , Anderson O. , Otter-Mann C. R.
Published: March 2011

Laser substrate heating is discussed as an alternative for the densification of sol -gel thin films. Homogeneous films of n(550 nm) = 2.30 could be obtained, keeping the bulk substrate temperature below 80 °C.
Hydrolysis and Condensation of Modified TIN (IV) Alkoxide Compounds to form Controlled Porosity Materials
Authors: Roger Christophe , Hampden Smith M. J. , Brinker C. J.
Published: March 2011

Sol-gel type hydrolysis and condensation has been studied extensively as a method for the control of evolution of microstructure in the formation of inorganic silicates. However, in non silicate systems, the same level of control of microstructural evolution has yet to be demonstrated. In this work, we report the synthesis of mixed ligand tin (IV) alkoxide complexes specifically designed to undergo sequential hydrolysis reactions, where, as a result, control over porosity of the final metal oxide network is expected. A series of tin (IV) alkoxide compounds modified with difunctional carboxylate ligands as templates has been prepared with internuclear tin separations that are determined by the length of the bridging carboxylate group. The first hydrolysis step consists of the removal of the alkoxide ligands to create a three-dimensional network of oxo-bridged tin carboxylate species. In the second step, the bridging groups are removed by acid hydrolysis to leave pores without creating new Sn-O-Sn bonds. The synthesis and characterization of these species and the connection between pore structure (i.e. micro- vs. meso- porosity) as a function of the dimensions of the bridging ligands will be reported.
Preparation of Low-Density Aerogels at Ambient Pressure
Authors: Smith Douglas M. , Deshpande Ravindra , Jeffrey Brinke C.
Published: March 2011

Low density aerogels have numerous unique properties which suggest a number of applications such as ultra high efficiency thermal insulation. However, the commercial viability of these materials has been limited by the high costs associated with drying at high pressures (supercritical), low stability to water vapor, and low mechanical strength. Normally, critical point drying is employed to eliminate the surface tension and hence, the capillary pressure, of the pore fluid to essentially zero. However, we show that by employing a series of aging and surface derivatization steps, the capillary pressure and gel matrix strength may be controlled such that gel shrinkage is minimal during rapid drying at ambient pressure. The properties (density, surface area, pore size, SAXS) of aerogel monoliths prepared from base catalyzed silica gels using this technique, supercritical CO2 drying, and supercritical ethanol drying are compared. An additional advantage of this approach is that the final gels are hydrophobic.
Leucite-Pollucite Glass Ceramics: A new Family of Refractory Materials with Adjustable Thermal-Expansion
Authors: Bedard R. L. , Broach R. W. , Flanigen E. M.
Published: March 2011

Novel ceramic compositions can be produced from carefully chosen, modified, and processed zeolites. The use of zeolites as precursors for leucite-pollucite glass ceramics having adjustable thermal-expansion behavior is described. The facile sintering properties of the zeolite-derived precursors allow production of these high-temperature materials at several hundred degrees below the solidus temperatures. A representative leucite-pollucite ceramic was studied by high temperature x-ray powder diffraction and synchrotron powder diffraction to determine the nature of the crystal structure and its relationship to the leucite and pollucite end members of the family.