bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleation and Crystallization of Amorphous Silicon-Aluminum Thin Films
Authors: Lin F. , Hatalis M. K. , Girginoudi S. , Girginoudi D. , Georgoulas N. , Thanailakis A.
Published: March 2011

The phase transformation of amorphous silicon-aluminum thin films with 16 at.% and 30 at.% aluminum was characterized by TEM during an in-situ anneal at 500°C. No crystallization was observed in the samples having 16 at.% Al even after a 10 hour anneal at 500°C. In contrast, nucleation of crystallites was observed in the samples having 30 at.% Al after a 40 min anneal. The size of these crystallites grew during annealing. Single crystal regions were also observed and were identified as aluminum having <111> orientation.
Epitaxial Growth and Charge Density Wave of TaSe2
Authors: Shimada Toshihiro , Ohuchi Fumio S. , Parkinson Bruce A.
Published: March 2011

We report an epitaxial growth of TaSe2, a family of transition metal dichalcogenides that exhibit Charge Density Waves (CDW). The films that have been characterized with RHEED, LEED, XPS and STM showed two different phases. Occurrence of CDW in the ultrathin films has been detected by XPS and LEED.
The Relationship Between Crystal Structure and Performance as Optical Recording Media In Te-Ge-Sb Thin Films
Authors: Strand D. , Gonzalez-Hernandez J. , Chao B. S. , Ovshinsky S. R. , Gasiorowski P. , Pawlik D. A.
Published: March 2011

The crystallization properties of Te-Ge and Te-Ge-Sb alloys prepared by thermal evaporation were analyzed using various characterization techniques. Similar to previous results, our data for Te-Ge shows that alloys that deviate slightly from Te50Ge50 stoichiometry show drastically slower crystallization kinetics. Raman spectroscopy and x-ray diffraction show that alloys having non-stoichiometric atomic ratios phase separate during crystallization into a Te50Ge50 phase plus pure crystalline tellurium or germanium. It is this relatively slow process of phase segregation which limits the crystallization rate. Phase segregation during crystallization of non-stoichiometric Te-Ge can be eliminated by adding antimony to samples having a tellurium concentration of from 45 to 55 atomic percent over a wide range of Ge:Sb ratios. These alloys can have laser induced crystallization times of less than 50 nsec. The thermal crystallization temperature is reduced only slightly when antimony is substituted for germanium.
Crystallization and Amorphization of Sic-Ceramic PVD Coatings After Laser Treatment
Authors: Knotek O. , Löffler F.
Published: March 2011

Over the last ten years, surface coating engineering has become a key technology throughout the world, especially due to the successes achieved in the optics and microelectronics sectors. First advances in the wear protection field were attained with coated carbides, indicating a substantial technical and economic potential in these areas.

The development of wear protective coatings often reaches the limits of what is technically possible. For this reason, processes incorporating two different methods and combining the specific advantages of each are increasingly being developed for the deposition of certain coatings. In the study presented here, PVD (Physical Vapour Deposition) technology was combined with laser surface treatment technology to produce amorphous and crystalline SiC coating phases. The objectives of the study were to establish the respective advantages of crystalline and amorphous phases. The amorphous ceramic coating exhibits excellent corrosion resistance, whereas the crystalline phases generally attain higher adhesion and superior stability at high temperatures. There are therefore technical applications for both phases.
Processing of Ferroelectric Memories
Authors: Paz De Araujo Carlos A. , McMillan L. D. , Scott J. F.
Published: March 2011

This paper describes the classification of existing integration schemes for ferroelectric memories, including both nonvolatile and volatile devices, and the status of device development for CMOS (both SRAM and DRAM architecture), GaAs JFET structures, bipolar, and true ferroelectric FETs (in which the ferroelectric is deposited in the gate region to modify the source-to-drain current when the polarization is reversed). Emphasis in the paper is on electroding, film deposition, drying and baking, and annealing steps.
Structure and Characterization of Sputtered Thin Films Based on Lead Titanate.
Authors: Pignolet A. , Schmid P. E. , Wang L. , Lévy F.
Published: March 2011

Pure and doped lead-titanate (PT) and lead-zirconate-titanate (PZT) thin films have been deposited on platinum-coated silicon by rf-magnetron sputtering from pressed powder targets. The films have been deposited without substrate heating. The amorphous films were then annealed in an oxygen flow. The structure of the films is tetragonal or rhombohedral depending on composition. The electrical resistivity, dielectric permittivity, ferroelectric hysteresis and pyroelectric coefficient are reported.
The Effects of Lead-Compensation and Thermal Processing on the Characteristics of DC-Magnetron Sputtered Lead Zirconate Titanate Thin Films
Authors: Chikarmane Vinay , Sudhama Chandra , Kim Jiyoung , Lee Jack , Tasch A I
Published: March 2011

The feasibility of the fabrication of thin film capacitors of Lead Zirconate Titanate (PZT) by reactive DC-Magnetron sputtering, with large switched charge and low leakage current densities for ultra-large scale integration Dynamic Random Access Memory (ULSI DRAM) applications has been demonstrated. As-deposited films were found to be predominantly pyrochlore; therefore, a subsequent phase transformation-inducing thermal processing step was key to obtaining device quality films. The importance of the thermal budget in optimizing the device characteristics of PZT films is discussed. The importance of the role of Pb compensation in lowering the required thermal budget and significantly enhancing device characteristics is shown.
Metal-Ferroelectric-Semiconductor Characteristics of BaMgF4 Films on p-Silicon
Authors: Kalkur T. S. , Kulkarni J. R. , Kwor R. Y. , Levinson L. , Kammerdiner L.
Published: March 2011

Capacitance-voltage characterstics of BaMgF4 film deposited in an ion-assisted deposition system shows hysteresis and the direction of hysteresis corresponds to ferroelectric polarization. Electrical characterization of the films shows that these films can be used to implement non-destructive read-out non-volatile ferroelectric memories. These films were found to dissolve in water and other aqueous solutions. In order to overcome this problem, a suitable capping layer like zirconium oxide and amorphous silicon was deposited on BMF films. The shift in threshold voltage did not change significantly due to the incorporation of the capping layer. The shift in threshold voltage was found to be temperature dependent and this might be due to ionic conduction in fluorides.
Direct Evidence of the Si Interstitialicy Injection and Fast diffusion effect in Si During Pulsed Laser Melt Process
Authors: Chang Yih , Chen J. , Talwar S. , Shu E. Y. , Sigmon Thomas. W.
Published: March 2011

High temperature gradient induced fast diffusion effect during pulsed laser melt processes is reported for the first time in the Si semiconductor. We use both the oxidationinduced stacking faults and dislocation loops as markers to determine the degree of enhanced diffusion in the unmelted Si substrate by tracing their movement after laser melt. The crosssectional transmission electron microscope is employed to investigate the defect structures before and after laser melt. The expanded dislocation loops exhibit a significant diffusion and climb occurring during the nanosecond-scale processing duration. We also formulate and solve the governed diffusion equation, based on a high temperature gradient induced electric field, to simulate the dislocation movement. The agreement between the experimental and simulated results verifies that the fast diffusion effect indeed occurs in the Si semiconductor during the pulsed laser melt period.
Preparation and Application of Magnetic Films by Ferrite Plating in Aqueous Solution
Authors: Abe M. , Itoh T. , Tamaura Y.
Published: March 2011

Ferrite plating invented by the authors facilitates formation of crystalline films of spinel, (Fe, M)3O4 (M=Fe, Ni, Co, Mn, Zn, etc.), in an aqueous solution below 100 °C. This opened the door to new ferrite-film devices which use, as substrate, such non-heat-resistant materials as plastics and GaAs ICs. In this paper we describe the principle and the experimental methods of ferrite plating and report magnetic and structural properties of the films. We also describe various applications of the ferrite plating films to microwave, electrochemical and bio-medical devices.
Imaging Magnetic Bit Patterns Using a Scanning Tunneling Microscope with a Flexible Tip
Authors: Moreland John , Rice Paul
Published: March 2011

Tunneling stabilized magnetic force microscopy (TSMFM) is a variant of scanning tunneling microscopy (STM) where the usual rigid STM tip is replaced with a flexible magnetic tip. This method contrasts with other magnetic force microscopes based on optical or capacitive detection of cantilever deflection due to magnetic forces. Instead, the position of the flexible tunneling tip depends on both topography and magnetic forces acting on the end of the tip. The z-motion of the piezoelectric translator flexes the tip to balance the magnetic force so that the end of the tip remains a fixed tunneling distance from the sample surface. We present a review of some TSMFM images showing the recorded bit patterns on hard disk, floppy disk, and tape surfaces. The images were taken in air using STM tips made from free-standing Fe and Ni films about 1 μm thick. The image resolution of TSMFM is routinely submicrometer. We conclude that this simple modification of STM will be a valuable diagnostic tool in the magnetic recording industry.
Crystal Structures and Magnetic Properties of Fe1 e N2 Films
Authors: Komuro Matahiro , Hoshiya Hiroyuki , Mitsuoka Katsuya , Kozono Yuzoo , Hanazono Masanobu , Sugita Yutaka
Published: March 2011

Fe-N films with thicknesses of 500–1000 Å have been epitaxially grown on lno-2 Gao-e As(001) substrates using MBE system. Deposition atmosphere was N2 + 20%NH3. and pressure during deposition was around 1 × 10−4 Torr. Two electron guns were used in order to control nitrogen concentration of 11 at% in Fe-N films. When substrate temperature was 150 °C, an Fe1 eN2 single crystal films were found to be formed after annealing at 150 °C. When the substrate temperature was around 300 °C, Fe1 eN2. films were grown epitaxial ly on lno-2 Gao-3 As without annealing, while Fe1 eN2 could not be grown at substrate temperature higher than 350 °C because of the formation of Fe2 As caused by the reaction between substrate and Fe–N films. RHEED and XRD patterns showed that Fe1 eN2 films was grown epitaxial ly and crystal orientation of Fe1 eN2 films are Fe1 eN2 (001)//lno-2 Gaoo-eAs(001) and Fe1 eN2 [100]//lno-2 Gaoo-e As [100]. Saturation magnetic flux density of Fe1 eN2 is 2.8˜3.0T.
Magnetic Properties of Fe/Ru and Fe/Ir Superlattices with Short Periodicity
Authors: Piecuch M. , Andrieu S. , Bobo J. F. , Maurer M. , Ravet M. F. , Dupuis V. , Ousset J. C. , Dieny B.
Published: March 2011

We present new results on the magnetic properties of constrained, iron base, good quality, single-crystalline superlattices, Fe/Ru and Fe/Ir. It is shown that in the first case there are two magnetically dead layers at the interface while in the second case there is probably none. The magnetic moment of Fe is, in both superlattices, about 1.7μb. The magnetic anisotropy are opposite, in plane for Fe/Ru, perpendicular for Fe/Ir.
Thermal Evolution of Magnetic Properties and Crystal Structure in Compositionally Modulated Al/Ni Thin Films
Authors: Waknis A. , Haftek E. , Tan M. , Barnard J. A. , Tsang E.
Published: March 2011

Periodic multilayer thin films of the form (xAl/yNi)n were grown by alternate deposition of pure Al and Ni using dc-magnetron sputtering. The thicknesses of the individual Al and Ni layers are given by x and y, respectively, and the total number of bilayer units is n. For this set of experiments, x was fixed at 3.5 nm while y was systematically varied from 2.4 to 154 nm. The films were tested in as-deposited and annealed states for magnetic properties using a vibrating sample magnetometer and for crystal structure by x-ray diffraction. In both the as-deposited and annealed samples the magnetization per unit volume of Ni declined as the Ni layer thickness decreased. This result can be interpreted in terms of a magnetically ‘dead’ layer at the Al/Ni interfaces. The width of the dead layer increased from 2.9 nm to 5.8 nm on annealing. Magnetic properties were correlated with crystal structure experiments by x-ray diffraction. As-deposited films yielded a Ni(111) texture. The Ni (111) peak decreased in intensity and broadened as the Ni thickness declined. Annealing produced evidence for the growth of the intermetallic NiAl3.
Periodic Length Dependence of Magnetic Properties in Fe/MnSb Multilayered Films
Authors: Nakagawa Shigeki , Tanaka Hiroki , Naoe Masahiko
Published: March 2011

The relationship between crystallographic and magnetic characteristics of multilayered films composed of Fe and MnSb layers were investigated in detail. The thicknesses of Fe and MnSb layers dFe and dMnSb were changed in the range of 50 ˜ 100 and 3˜ 100 Å, respectively. Although only the (110) oriented α-Fe crystallites appeared in the films with dMnSb as small as about 5 Å, both of X-ray diffraction peaks of Fe and MnSb crystallites were not detectable in one with dMnSb of about 15 Å. The growth of both Fe and MnSb crystallites seemed to be strongly prevented in the films with dMnSb in this range. On the contrary, the peaks corresponding to (110)Fe and (110)MnSb appeared in X-ray diffraction diagram for the film with dMnSb above 25 Å. The films with d of 10 Å and dFe of 20 Å exhibite the saturation magnetization 4πMs of 15 kG and the coercivity Hc of 0.2 Oe. Such a low Hc was two order lower than those of both Fe single layer film and MnSb one. This seems to be attributed to the fine granulation of Fe and MnSb crystallites.
Magnetic Properties of Nanocrystalline Fe-Based Soft Magnetic Alloys
Authors: Yoshizawa Yoshihito , Yamauchi Kiyotaka
Published: March 2011

Magnetic properties of nanocrystalline alloys produced by crystallization of Fe-Cu-Nb-Si-B amorphous alloys have been investigated. The best result is obtained at the annealing conditions where the main phase is bcc and it is very important to suppress the formation of Fe-B compounds with large magnetocrystalline anisotropy. Homogeneous and ultrafine grain structure has an important effect to improve the magnetic properties. Conclusively, soft magnetic properties of nanocrystalline alloys are related to various factors such as formed phases, ratio of amorphous phase, intrinsic magnetocrystalline anisotropy and magnetic interaction from grain boundary phase.
The Magnetic Anisotropy of Co-Base Amorphous Alloys
Authors: Zhang Wu-Xin , Li Xi-Ming , Chen Nan-Ping
Published: March 2011

4 Co–base amorphous alloys prepared by rapid quenchling are stress–annealed under different temperature (Ta) balow its crytalline temperature Tcry, after pre–annealing. The effect of magnetic anisotropy with Ta shows the mechanism of stress–induced anisotropy is changed from single ionic modal to pair model as Ta inereases. The effect of Mn content may exaggerate the model changing.
Effect of Cu and Al Substitutions on the Microstructure of R-Fe-B Magnets
Authors: Zhang Y. J. , Withanawasam L. , Hadjipanayis G. C. , Kim A.
Published: March 2011

The coercivity of melt-spun Pr-Fe-B ribbons was found to increase with the addition of Cu and Al. The change in size and shape of grains with Cu and Al substitution were investigated by transmission eletron microscopy (TEM) and the grain boundary structure was further examined with high resolution electron microscopy (HREM). For small substitutions only “disturbed lattice” regions were observed at most of the grain boundaries. Secondary phases rich in the added elements were observed mostly at tripple grain boundaries and sometimes at grain boundaries in samples with larger amounts of substitution. The grain size in the substituted samples does not decrease much with further substitution. However, the shape of grains changes from polyhexagons to facets. The enhancement in coercivity can be explained by the grain size reduction and the modification of microstructure at the grain boundary regions.
In Situ Tem Study of Amorphous to Crystalline Transformation in R-Fe-B Ribbons
Authors: Zhang Y. J. , Wang Y. Z. , Hadjipanayis G. C.
Published: March 2011

The amorphous-crystalline transformation in R-Fe-B ribbons was studied in situ in a transmission electron microscope (TEM) and with X-ray diffraction. Metastable phases of α-Fe(R) and Fe3B were found to form during crystallization before the final R2Fe14B phase is formed. The Fe3B phase is believed to be important for the formation of the 2:14:1 phase because its “local unit structure” is one of the basic building blocks in the 2:14:1 unit cell.
Chromium Underlayer Effects in Longitudinal Magnetic Recording
Authors: Doerner M. F. , Wang P.-W. , Mirzarnaani S. M. , Parker D. S.
Published: March 2011

For media used in longitudinal recording, an epitaxial relationship is observed between the Cr and Co-alloy layers, and generally a strong Cr <100> texture is desirable for c-axis in-plane orientation of the Co alloy. In this study, Cr underlayer thickness, temperature and Cr deposition pressure were varied while keeping the magnetic layer (CoPtCr) deposition process constant. Films were deposited on circumferentially textured NiP, polished NiP and chemically elched NiP substrates as well as Si wafers in order to study the effects of surface finish on the crystallographic orientation of the Cr underlayer. The uniformity of the magnetic properties and in-plane anisotropy (orientation ratio) of the disks were measured using Kerr magnetrometry. The in-plane anisotropy was found to be related to the Cr deposition conditions and the surface texture of the NiP. Signal to noise ratio results and a possible mechanism for the origin of the in-plane anisotropy are discussed.
Conversion Electron Mossbauer Spectroscopy of Epitaxial Iron Oxide Films
Authors: Takano M. , Fujii T. , Bando Y. , Isozumi Y. , Katano R. , Okuda T.
Published: March 2011

Epitaxially grown iron oxide films have been studied microscopically by conversion electron M~ssbauer spectroscopy. Specially designed proportional counters cover a temperature range between 1.75K and 1100K. A 5Å-thick layer containing 57Fe was grown at an arbitrary depth of a 56 Fe3O4 film, even- at the topmost or at the interface with a substrate crystal, to find local properties nondestructively. Temperature dependence of the hyperfine parameters of Bi 3 Fe5O12 films were analyzed to find structural and magnetic effects of Bi3+ in comparison with usual garnets. The Morin transition of α-Fe2O3 was found to strongly depend upon the orientation of films and post-annealing.
Magnetic Properties and Microstructure of Co-Pt-B-O Alloy Films
Authors: Hayashi K. , Iwasaki Y. , Okabe A. , Yamamoto T. , Hayakawa M. , Aso K.
Published: March 2011

Co-Pt-B-O alloy films show the magnetic properties of saturation magnetic induction 4TπMs = 12 kG, perpendicular coercivity Hc(⊥) = 5 kOe, and perpendicular anisotropy field Hk(⊥) = 23 kOe. These characteristics are easily controlled by changing the film composition. The perpendicular magnetic anisotropy field and the coercivity of the Co-Pt-B-O alloy films have close correlation with the film microstructure. To clarify this relation, the individual effects of oxygen and boron in the Co-Pt binary alloy film were investigated. The addition of boron makes the average grain size smaller, whereas the column diameter remains unchanged. The addition of oxygen to the Co-Pt binary alloy reduces the column diameter to about 5–10 nm, whereas the columns are densely packed without any gaps. The sole addition of oxygen or boron neither increases the perpendicular anisotropy nor the coercivity. The high perpendicular anisotropy and the large coercivity are derived from the fine columnar structure of 5–10 nm in diameter coupled with the inter-columnar gaps of about 1 nm and are obtained by the co-additions of oxygen and boron.
Microstructure of Electroless-Plated CoNiReP/NiMoP Double-Layered Media for Perpendicular Magnetic Recording
Authors: Osaka T. , Homma T. , Noda K. , Asai H.
Published: March 2011

The microstructure of the electroless-plated CoNiReP/NiMoP doublelayered media was examined with various methods and the origin of the inplane anisotropy initial regions of the CoNiReP recording layers was discussed. It was confirmed that the initial region consists of randomly oriented fcc phase with Ni-rich composition, showing the granular condition, while the perpendicular anisotropy region at the top consists of <002> perpendicularly oriented hcp phase, showing the columnar structure. It is considered that the formation of the initial region is due to a preferential deposition of Ni onto the underlayers, and that the thickness of the initial region changes due to a change in the condition of the underlayers, especially that of deposition activity and/or morphology at their surfaces.
Magnetic Properties of Co/Pt Multilayers on MgO (100) Substrates
Authors: Krishnan R. , Lassri H. , Porte M. , Tessier M. , Flevaris N. K.
Published: March 2011

We have prepared Co/Pt multilayers by evaporation in UHV on MgO (100) substrates kept at various temperatures. Most of the samples were grown on a Pt buffer layer. Magnetic and magneto-optical properties have been studied. The surface anisotropy Ks for MgO substrates is 0.35 erg.cm−2 which is smaller than 0.6 erg.cm−2 obtained for glass substrates. The effect of the growth conditions on Ks is observed only for t(Co)<10 Å where the crossover to Keff>O occurs. Deposition at higher temperature leads to an increase in the coercivity. The magnetization and the anisotropy is practically temperature independent in the range 5 to 295 K. However the coercivity increases sharply below 100K.
Recent Developments in the use of the Tripod Polisher for TEM Specimen Preparation
Authors: Benedict John , Anderson Ron , Klepeis Stanley J.
Published: March 2011

Cross sections of material specimens for TEM analysis must be produced in the shortest time possible, contain few, if any, artifacts and have a large area available for analysis. The analyst must also be able to prepare these cross sections from specified areas of complex, heterogeneous structures on a routine, reproducible basis to meet the growing needs of the semiconductor industry for TEM analysis. The specimen preparation spatial resolution required for preparing precision cross sections is substantially less than one micron. Cross sections meeting these requirements can be prepared by mounting a specimen to the Tripod Polisher and mechanically polishing on one side of the specimen, using a sequence of progressively finer grit diamond lapping films, until the area of interest is reached. This polished surface is then very briefly polished on a cloth wheel with colloidal silica to attain the final polish on that side. The specimen is then flipped over on the Tripod Polisher and polished from the other side, using same sequence of diamond lapping films to reach the predefined area of interest. The Tripod Polisher is set at a slight angle, to produce a tapered, wedge-shaped specimen, which has the area of interest at the thinnest edge of the taper. The specimen is polished with the diamond lapping films and the colloidal silica until it is 1000 Angstroms or less in thickness. The specimen is removed from the polisher and mounted on a 2 × 1mm slotted grid with M-Bond 610 epoxy. After the epoxy is cured the specimen can be taken directly to the microscope for analysis. The need for ion milling has been eliminated or reduced to a few minutes in most of our work because of the thinness of the final specimen. The total specimen preparation time is between 2.5 and 4 hours, depending on the specimen and the size of the specified area. The area available for analysis ranges from 0.5mm up to the full size of the mounting grid opening. The wedge shape of the specimen provides the mechanical stability needed for a long thin specimen.
Preparation of Planview TEM Samples of Yba2Cu307−x Films Grown on BaF2(001)
Authors: Li Yang , Jinlong Zhang , Chenggao Fan , Yuheng Zhang
Published: March 2011

A method for the preparation of planview transmission electron microscope (TEM) specimens of expitaxial Yba2Cu3O7−x (YBCO) thin films deposited on BaF2 by a dc modified planar magnetron sputtering technique is reported. The films are granular with their grains size ranging from a few hundred to a few thousand nanometers. The epitactic nature of the film growth is shown by analyses of moiré fringe patterns and by selected area diffraction methods. It is demonstrated that the YBCO thin film obtained is highly c-axis oriented, with misorientation corresponding to rotations of 9.2° and 90° about the c-axis. Additionally, the film's a or b axes form a 45° angle with that of the substrate.
Minimization of Non-Uniform Ion-Thinning Effects in Thin Film Transverse Specimens for Transmission Electron Microscopy
Authors: Shaapur F. , Watson K. A.
Published: March 2011

A computer-controlled, specimen rotation attachment was developed and installed on a commercial ion-milling system for TEM specimen preparation. This rotation method produced relatively large thin areas on a variety of thin film transverse specimens with a difference in the ion-milling rates between the film and the substrate. The results were generally comparable to those obtained by a newly developed low-angle ion-thinning procedure and the overall processing time was considerably shortened.
Advanced Preparation of Hard Materials for Cross-Sectional Tem Analysis
Authors: Ostreicher Kim , Sung Changmo
Published: March 2011

The preparation of cross-sectional specimens for materials such as tungsten carbide containing ceramic coatings presents some unique problems. Pieces joined by the use of epoxies often separate at this interface during subsequent preparation steps as a result of the vibration and physical strain placed on the sample during the initial mechanical grinding and subsequent thinning process. These problems have been overcome through the use of a preparation process which essentially encapsulates the sample within the confines of an epoxy filled quartz tube. This preparation process has allowed for the cross-sectional analysis of Al2O3/TiC coatings on WC substrates and has revealed two distinct grain morphologies within the TiC coating.
Precision Tem Sample Preparation Using Focused Ion Beam Marking Strategies
Authors: Sanborn Christopher E. , Myers Sharon A.
Published: March 2011

Focused ion beam (FIB) etching has been shown to be an effective method for TEM sample prep. The system uses a finely focused beam of gallium ions to remove surface material from selected areas. When used in conjunction with a metal-organic gas source, a conductive layer can be deposited in specific areas.

In a production atmosphere, it is not always possible to use the FIB equipment for the length of time required to completely prepare a cross-sectional sample. Instead, the FIB has been used to indicate specific areas, such as blown fuses or shorts by “marking” the area so that it is easily optically located. Unconventional TEM sample prep techniques were developed to prepare the cross-sectional samples from specific target areas.
Reduced Amorphization of Ion-Milled Silicon Cross-Section Transmission Electron Microscope Samples by Dynamic Annealing During Milling.
Authors: Bahnck D. , Hull R.
Published: March 2011

We have developed an experimental apparatus for heating samples in the temperature range 50–400°C during ion milling. We find that heating to temperatures > 250°C during milling greatly reduces ion sputtering amorphization of the sample surfaces, due to dynamic reannealing of point defects. This allows thinner regions of crystalline sample to be imaged, without the signal being swamped by noise due to milling amorphization. At temperatures ≥300°C, however implantation defects am formed. We discuss the advantages of this technique for high resolution imaging.
Shaping Particles for Ultramicrotomy
Authors: Bradley C. R. , Dietz N. L. , Bates J. K.
Published: March 2011

A technique for preshaping large particles of reacted glass for ultramicrotomy is described. This technique preserves delicate surface layers and results in more sections per block extending deeper into the sample than other techniques.
Topographic Kinetics and Practice of Low Angle Ion Beam Thinning
Authors: Barna Árpád
Published: March 2011

The thinning technique is based on a simple geometrical model, describing the changes in the surface topography during ion beam etching. A high ion beam density makes jt possible that a thinning with an incidence angle of 0.5–7° ( measured from the sample surface) can take place within a reasonable time. Our method is applicable to a wide range of materials and to XTEM preparation.
Advancements in Dimpling Technique for Automatically and Repeatably Thinning TEM Samples to Near Electron Transparency
Authors: Caruino Vincent L. , Hidalgo August J.
Published: March 2011

One of the latest advancements in technique for preparing materials for TEM examination was first made commercially available by VCR Group in 1982. The instrument, known as the DIMPLER®, mechanically thins materials by “dimpling”, a technique which has become widely accepted by material scientists. Since its inception other manufacturers have also produced dimpler-like instruments.
Interpenetrating Organometallic Polymer Networks (IOPN's): Novel Advanced Materials
Authors: Corain B. , Zecca M. , Corvaja C. , Palma G. , Lora S. , Jerabek K.
Published: March 2011

A cross-linked copolymer of vinylferrocene and dimethyl-acrylamide is generated inside the less dense microporous domains of a cross-linked polydimethylacrylamide matrix. I.S.E.C. and E.S.R. data reveal that the obtained composite is in fact an I.P.N.(Interpenetrating Polymer Network) material.
A Novel Epoxy Resin Toughened by HTBN Liquid Rubber
Authors: Han Xiaozu , Yun Zhankui , Guo Fenchun
Published: March 2011

A novel toughened epoxy resin was obtained by using an epoxy-terminated prepolymer prepared from epoxy resin and hydroxy-terminated butadiene-acryl-onitrile copolymer (HTBN), and an amine curing agent. The cured, toughened resin has excellent mechanical properties due to the two-phase structure which was observed using SEM and TEM. When the HTBN content is 15 phr, the rubber phase separates effectively and the specimen presents a fine two-phase structure. However, when the HTBN content reaches 25 phr, the morphology appears continuous.
Variable Frequency Conductivity of Layered Polypyrrole / V2O5 Composites
Authors: DeGroot D. C. , Schindler J. L. , Kannewurf C. R. , Liu Y.-J. , Wu C.-G. , Kanatzidis M. G.
Published: March 2011

The frequency dependent electrical properties of the intercalated polypyrrole/V2O5 system have been measured. This study continues the investigation into the charge transport mechanisms that have been identified in these layered polymer/inorganic composites. The polypyrrole/V2O5 material is prepared by in-situ oxidative polymerization of pyrrole in the intralamellar space of the V2O5 xerogel. This process produces a layered, two-dimensional structure in which the charge transport properties result from two parallel conduction paths: the polypyrrole chains and the V2O5 layers. Impedance spectroscopy data have been collected from free-standing film samples of the layered polypyrrole/V2O5. The experiments were conducted over the frequency range of 10 Hz to 0.5 GHz and a temperature range of 77 to 310 K. The polypyrrole/V2O5 impedance results are presented in various equivalent forms and compared to data collected from pristine V2O5·nH2O, and reduced Cs0.14V2O5·nH2O.
Al2O3-ZrO2 Ceramics with Submicron Microstructures Obtained through Microwave Sintering, Plasma Sintering and Shock Compaction
Authors: McKittrick J. , Tunaboylu B. , Katz J. D. , Nellis W.
Published: March 2011

Submicron and nanocrystalline grain sizes were achieved in the Al2O3-ZrO2 eutectic composition through conventional, microwave and plasma sintering of rapidly solidified starting powders and through shock compaction of commercial powders. Post sintering studies revealed nanocrystalline intragranular ZrO2 in the 1–2 μm Al2O3 grains, which is thought to be a result of the solidification synthesis. Additions of B2O3 greatly increased the final density through liquid phase sintering. Shock compression of commercial powders produced dense, crack-free, fine grained ceramics with loading pressures up to 9.1 GPa and a metastable ZrO2 phase under higher pressures.
Synthesis of Carbon/Ferrite Composite by In-Situ Pressure Pyrolysis of Organometallic Polymers
Authors: Hirano Shin-Ichi , Yogo Toshinobu , Kikuta Koichi , Fukuda Makoto
Published: March 2011

Ferrite particle-dispersed carbon composite were synthesized by in-situ pressure pyrolysis of organometallic polymers at temperatures from 500 to 700°C under 125 MPa. Magnetite-dispersed carbon composite could be prepared from 550 to 700°C at 125 MPa. Nickel and nickel zinc ferrite particles were dispersed in carbon matrices at 550°C and 500°C, respectively, under 125 MPa. The morphology of the carbon matrix can be controlled by the pyrolysis conditions and the amount of coexistent supercritical water. Carbon spherulites of several micrometers dispersed with ferrite particles less than 100 nm were successfully synthesized by pressure pyrolysis of organometallic polymers in the presence of supercritical water. The saturation magnetization of magnetite-, nickel ferrite- and nickel zinc ferrite-dispersed carbon were 74, 30 and 65 emu/g, respectively. The coercive force of nickel ferrite-dispersed carbon was about 200 Oe.
Magnetic Properties of Mechanically Alloyed Nano-Crystalline Cu/Fe Composites
Authors: Reed C. P. , Axtell S. C. , De Angelis R. J. , Robertson B. W. , Munteanu V. V. , Liou S. H.
Published: March 2011

Metal powders of the composition 70 at% Cu and 30 at% Fe were produced by high energy mechanical alloying of the elemental powders. The powders were processed in a Spex 8000 mixer/mill for various times to investigate the potential of the mechanical alloying process for producing nano-composite structures with modified magnetic properties. Optical microscopy revealed a layered structure of alternating copper and iron that developed upon milling. The spacing between the layers decreased with milling time, becoming optically unresolvable (< 1μm) after four hours of milling. A single profile x-ray diffraction profile shape analysis technique was used to determine the average diffracting particle size of the copper and iron phases. The diffracting particle size decreases with alloying time reaching values of 7.5 nm and 2 nm, for copper and iron respectively, after eight hours of alloying. The magnetic coercivity increased with milling time initially, reaching a maximum value above 300 Oe after six hours of milling. These results are discussed and compared to results obtained in Ag/Fe and Cu/Fe nano-composite films.
High Temperature Polymer Nanofoams
Authors: Hedrick J. , Labadie J. , Russell T. , Wakhiarkar V. , Hofer D.
Published: March 2011

A means of generating high temperature polymer foams which leads to pore sizes in the nanometer regime has been developed. Foams were prepared by casting block copolymers comprised of a thermally stable block and a thermally labile material, such that the morphology provides a matrix of the thermally stable material with the thermally labile material as the dispersed phase. Upon a thermal treatment, the thermally unstable block undergoes thermolysis leaving pores where the size and shape of the pores are dictated by the initial copolymer morphology. Nanopore foam formation is shown for triblock copolymers comprised of a poly(phenylquinoxaline) matrix with poly(propylene oxide) as the thermally labile block. Upon decomposition of this block, a 10–20% reduction in density was observed, consistent with the initial PO composition, and the resulting PPQ foam showed a dielectric constant of ∼ 2.4, substantially lower than PPQ (2.8). Small angle X-ray scattering and transmission electron microscopy show pore sizes of approximately 100Å.
Characterization of Thermotropic Liquid Crystalline Polymer Blends by Positron Annihilation Lifetime Spectroscopy
Authors: Naslund Robert A. , Jones Phillip L. , Crowson Andrew
Published: March 2011

Positron annihilation lifetime spectroscopy (PALS) is used to investigate polymer-based molecular composites of two separate thermotropic liquid crystalline polymers (TLCPs) and the thermoplastic matrix polyetherimide. Trends in PALS spectral components obtained isothermally at 20°C and 120°C as a function of TLCP content are discussed as a function of free volume and molecular structure. Differential scanning calorimetry was employed as a complementary technique to investigate the differences in miscibility of the two systems and possible effects on positron lifetime values.
Small Angle Neutron Scattering Studies of Single Phase IPNs
Authors: Bauer Barry J. , Briber Robert M. , Malone Shawn , Cohen Claude
Published: March 2011

Interpenetrating polymer networks (IPNs) have been synthesized from polymers that form miscible polymer blends. Full, semi-I and semi-II IPNs made from polystyrene-d8 and poly(vinylmethylether) can be made to phase separate by incorporating low levels of crosslinking. However, blends of these polymers have a negative Flory-Huggins interaction parameter, making them highly miscible. This indicates that formation of IPNs favors phase separation relative to blends.

IPNs made from polystyrene-d8 and polystyrene-h8 show that increased crosslink density also destabilizes the mixture as shown by small angle neutron scattering.

IPNs have also been made by crosslinking end functionalized polydimethylsiloxanes in the presence of nonfunctionalized, deuterated siloxanes. These IPNs are also destabilized by increasing crosslink density, suggesting that the destabilization is due to the network, and not to the particular type of network forming reaction.
Reinforcement in Silicone Elastomers. A Short Review
Authors: Saam John C.
Published: March 2011

Selected topics on the use of particulate solids to build modulus and strength in silicone elastomers are briefly reviewed. Included are recent views advanced to explain the reinforcement phenomena, some more current approaches to particulate reinforcement and recommended areas for future endeavor.
Effect of Hydrogen on Dislocation Emission from a Crack Tip in Nickel
Authors: Hoagland Richard G.
Published: March 2011

A method for determining the intrinsic resistance to dislocation emission and glide in atomic models is presented and applied to EAM models of nickel containing a single-ended crack tip. The method is an adaptation of the Peierls approach in which the work done on the glide plane is computed as a function of dislocation position and its derivative is the intrinsic resistance to dislocation motion. The results indicate that there are two parts to the resistance dislocation glide from the crack tip: a distinct barrier to injection of the dislocation from the crack tip and a periodic resistance associated with the lattice. When a hydrogen interstitial is placed on the slip plane near the crack tip the barrier height is reduced but its width is increased.
A Study on First Principle Calculation of Alloy Phase Diagram by Monte Carlo Simulation
Authors: Sawada Hideaki , Nogami Atsushi , Yamada Wataru , Matsiuniya Tooru
Published: March 2011

A method of first principle calculation of alloy phase diagram was developed by the combination of first principle energy band calculation, cluster expansion method (CEM) and Monte Carlo (MC) simulation, where the effective multi-body potential energy for the flip test in MC simulation was obtained by the decomposition of the total energy by CEM. This method was applied to Cu-Au binary system. The calculated phase diagram agreed with that of CVM by introducing the dependence of the lattice constant on the concentration of the whole system. Furthermore an attempt of introducing the effect of local lattice relaxation was performed by the consideration of the local concentration. The order-disorder transition temperature became closer to the experimental value by adjustment of the local lattice constant depending on the concentration in the local region consisted of up to the second nearest neighbors of the atom tested for flipping.
Dynamics of a Metal Overlayer on Metallic Substrates – High Temperature Effects
Authors: Rahman Talat S. , Black John E. , Tian Zeng Ju
Published: March 2011

We have explored the structure and the dynamics of a bimetallic system consisting of a hexagonal (almost) overlayer of Agon a square lattice (Ni(100) and Cu(100)), as a function of the surface temperature. In each case the structure is "nearly" incommensurate giving rise to a low frequency Goldstone mode. Also, the overlayer atoms slosh back and forth over the substrate in a corrugated fashion. The calculated dispersion of the Ag/metal vertical mode, at room temperature, is in excellent agreement with experimental data. At higher temperatures floater atoms appear on top of the overlayer displaying a variety of cluster formations and also exchanges with the substrate atoms leading to surface disordering, interdiffusion and melting.
Cooperative Pseudo Jahn-Teller Effect as Microscopic Mechanism of (OMT)-(LTT) Structural Phase Transition in La2−xBaxCuO4Superconductors
Authors: Kaplan Michael D.
Published: March 2011

A microscopic mechanism for the structural phase transition from the orthorhombic mediate temperature (OMT) phase into the low temperature tetragonal (LTT) one is suggested on the basis of the cooperative pseudo Jahn-Teller effect. The local distortions mixing the ground and the first excited electronic states are ordered antiferrodistortively and are connected in part, with the oxygen octahedra rotations around the [100] axis. The results are in agreement, with the neutron scattering experiments data.
Electronic Properties of Alumxna/Titania Mixed Oxides and Interfacial Surface Models: a Theoretical Analysis
Authors: Jansen S.A. , Grabania S.A. , Buecheler N.M. , Whitwell G.
Published: March 2011

Alumina is a common contaminate of titania, which is found in paints and food additives. Recently, thin films of rutile TiO2 grown on sapphire (α-Alumina) have received attention for possible use in electronic and optical devices.1−3 However, the alumina-titania interface has not been well characterized. In this work we report an extensive analysis of the alumina-titania interfacial relationship. Using existing structural data4, models of common alumina and titania surfaces have been constructed. The model used maximizes the commensurability between the two structures. Semi-empirical/tight binding calculations have been employed to examine the monolayer as well as the interfacial electronic properties in terms of chemical interaction potential and stability.
Ionic Overlayers on Corrugated Surfaces I: Structure
Authors: Çağin Tahir , Sen Surajit , Seong Hyangsuk , Mahanti S.D.
Published: March 2011

Structural and dynamic properties of a large class of intercalation compounds can be modelled by a collection of ions interacting via a screened Coulomb potential and subjected to the corrugation potential produced by the host atoms. In this paper we discuss the results of Molecular Dynamics simulation studies of the ground state structure of RbC24 and related systems focussing primarily on the micro-structure i.e.on the nature of the domains and domain walls.
Reactions and Segregation on α-Cristobalite (011) Surfaces by the Electronegativity Equalization Method
Authors: Mullins W. M.
Published: March 2011

The electronegativity equalization method is used to calculate the atomic charges, framework electronegativity and framework energy of the α–cristobalite bulk and the relaxed (011) surface. The effect of surface hydration and fluoridation on the framework properties are then calculated and related to surface charge. The segregation of germanium, aluminum and phosphorus in the α-cristobalite structure are modelled using the same method. The framework electronegativity difference between surface and bulk is observed to be a driving force for reactions and segregation.
Ionic Overlayers on Corrugated Surfaces II: Melting
Authors: Seong Hyangsuk , Mahanti S.D. , Sen Surajit , Çağin Tahir
Published: March 2011

Using molecular dynamics simulation we have investigated the melting properties of a 2-dimensional system of ions interacting through a screened Coulomb potential in the presence of a substrate. We focus on the role of the substrate potential in the melting transition. The physical system we study is the stage-2 graphite intercalation compound RbC24 and a related system RbC24,57 whose intercalant density differs from the former by a small amount. Our results reveal the nature of melting processes characteristic of periodic domain wall solids.
Elastic Modulus of the (GaA.s)m(A.l A.s)n Superlattices
Authors: Mirovitskii Vadim Yu.
Published: March 2011

The ultrathin (GaAs)m (AlAs)n superlattices ( SL ) grown along [001] are formally considered as a result, of ordering-type phase transition from an initial hypothetical mixed crystal (Gax Al1-x)As with x = m/(m+n) . From this point of view changes of elastic modulus tensor (EMT) induced by ordering can he calculated nearly in a spirit of phenomenological Landau theory of second-order phase transitions. It .is shown that a change of EMT component. S66 is completely determined by symmetry properties of two translational (Dzyaloshinskji) invariants of m+n power .in the expansion of SL thermodynamic potential in a power series .in order parameter components. The changes of the other EMT components depend on the second power of order parameter .The expressions are found out to connect. EMT of a definite ordered phase (SL - family with m+n = 3) with that, of the initial one.
An Electrostatic Induction Model for Fluoroalkane Polymers
Authors: Carbeck Jeffrey D. , Rutledge Gregory C.
Published: March 2011

An electrostatic induction model based on atom-centered partial charges is presented. In this representation, the local electric field is evaluated at each bond center. The bonds are treated as entities polarizable only in a direction parallel to the bond itself by means of a scalar bond polarization parameter. The resulting induced charge separation contributes to the local electric field experienced by neighboring bonds, resulting in a final set of charges which are calculated self-consistently. The model provides a reasonable approximation to dipole moment vectors and polarizabilities of small molecule fluoroalkanes. The results are discussed in comparison with other induction models. This model fits well into the framework of established atomistic potential energy calculations using an atom-centered partial charge representation.
Electronic Structure of LaBO3(B=Mn,Fe,Co,Ni,Cu) Perovskites and La2NiO4
Authors: De La Mora P. , De Teresa C. , Vicente L.
Published: March 2011

The electronic structure ofLaBO3 perovskites and La2NiO4 perovskite- like materials (where B = Mn,Fe,Co,Ni,Cu) have been studied inside a tight binding scheme using the extended Hückel Method. An analysis of the metal- oxygen bond is presented as well as the electronic structure in order to establish a correlation between electronic properties and catalytic activity (oxidation) of these compounds.