| Glassy Transformation and Structural Change in Ge2Sb2Te5 Studied by Impedance Measurements |
JUN 2001 |
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| Authors:
E. Morales-Sanchez; J. Gonzalez-Hernandez; E. Prokhorov; NATIONAL UNIV OF MEXICO MEXICO CITY DIV DE ESTUDIOS DE POSGRADO FACULTAD DE INGENIERIA
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 | The transition form amorphous-to-crystalline (fcc) has been investigated in Ge(2)Sb(2)Te(5) thin film alloys. This composition is the most frequently used for erasable optical memory devices. The phase transition was monitored using in situ impedance measurements as a function of temperature. The results were analyzed using the Maxwell-Wagner and brick models. From the impedance measurements it is possible to detect the appearance of nucleation centers in samples heated at temperatures below ... |
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| Thermally-Induced Structural Changes in Copper-Containing Chalcogenide Thin Films |
JUN 2001 |
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| Authors:
S. R. Lukie; D. M. Petrovie; N. Cvejic; A. F. Petrovic; F. Skuban; INSTITUTE OF PHYSICS NOVISAD (YUGOSLAVIA) FACULTY OF SCIENCES
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| Thin-film samples of the system Cu(x)(AsSe1.4I0.2)1-x, x |
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| High-Purity Glasses Based on Arsenic Chalcogenides |
JUN 2001 |
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| Authors:
M. F. Churbanov; I. V. Scripachev; G. E. Snopatin; V. S. Shiryaev; V. G. Plotnichenko; RUSSIAN ACADEMY OF SCIENCES MOSCOW INSTITUTE OF CHEMISTRY OF HIGH PURITY SUBSTANCES
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| Low impurity content is the essential requirement to many applications of vitreous arsenic chalcogenides as a material for optoelectronics. Investigations carried out in last ten years increased the knowledge volume about the nature and origin of impurities in chalcogenide glasses, their effect on glass properties, especially on the transmittance in middle IR region and on radiation strength. These properties are most sensitive to impurity presence. The minimum calculated content of ... |
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| Opto-Mechanical Effect in Chalcogenide Glasses |
JUN 2001 |
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| Authors:
M. Stuchlik; P. Kreemer; S. R. Elliott; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF CHEMISTRY
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| The opto-mechanical effect observed in amorphous chalcogenide films deposited onto clamped STM cantilevers 1 has been investigated. In this, bandgap light, incident on the chalcogenide film and linearly polarized either parallel or perpendicular to the cantilever axis, reversibly causes respectively either a contraction or an expansion of the chalcogenide layer, resulting in an optically-actuated displacement of the free end of the clamped cantilever. This effect is electronic, not thermal, in ... |
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| Waveguides Based Upon Chalcogenide Glasses |
JUN 2001 |
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| Authors:
V. Balan; C. Vigreux; A. Pradel; M. Ribes; LABORATOIRE DE PHYSICOCHIMIE DE LA MATIERE CONDENSEE CEDEX (FRANCE)
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| Because of their transparency in the infrared, their high refractive index and their well-known photosensitivity properties, interest in chalcogenide glasses for integrated optics and technological applications related to detection in the IR spectral domain has been growing during the past few years. Our present work is focused on the possibility of integrating chalcogenide glasses in components for two types of applications: spatial interferometry (detection of planets) and environmental metrology (detection ... |
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| Resemblance of Laser Light and Electric Field Information Recordings on Chalcogenide Glassy Semiconductors |
JUN 2001 |
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| Authors:
K. D. Tsendin; E. A. Lebedev; Young-Ho Kim; In-Jong Yoo; E. G. Kim; ANALYSIS DESIGN AND DIAGNOSTICS INC JACKSONVILLE FL
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| One of the most known reversible memory effect in chalcogenide glassy semiconductors (CGS) is associated with a reversible glass-crystal phase transition. In contrast to the photo-structural effect, which is associated with a reversible structural changes between two metastable disordered glassy states, the glass-crystal phase transition in CGS can be initiated and reversed not only by power light but by an electrical voltage also. These facts give us a principle opportunity ... |
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| Preparation and Properties of Non-Crystalline Glasses in the System Se-I |
JUN 2001 |
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| Authors:
S. Zamfira; D. Ursutiu; TRANSYLVANIA UNIV BRASOV (ROMANIA) DEPT OF PHYSICS
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| Vitreous Se(x)I(1-x) samples (x=0.l; 0.15; 0.20) have been prepared and studied by thermal analysis, iodometry, X-ray diffraction and optical transmission. The results show that part of iodine remains unbonded in the structure while another part saturates the ends of selenium chains. The main effect of the iodine atoms upon the selenium matrix configuration consists in the shortening of the selenium chains and occupation of the short chain ends by atomic ... |
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| Structure and Properties of Chalcogenide Glasses in the System (As2S3) sub 1-x (Sb2S3) sub x |
JUN 2001 |
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| Authors:
F. Sava; NATIONAL INST OF MATERIALS PHYSICS BUCHAREST (ROMANIA)
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| The glass system (As2S3)1-x(Sb2S3)x, 0 |
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| Compositional Dependence of the Optical Properties of The Ge-Se-Ga Glasses |
JUN 2001 |
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| Authors:
Y. Nedeva; T. Petkova; E. Mytilineou; P. Petkov; PATRAS UNIV (GREECE) DEPT OF PHYSICS
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| Optical properties of the glasses from the systems with a constant ratio of Ge/Se and different concentrations of gallium are investigated. The spectral dependence of the absorption coefficient a, is calculated from transmission spectra. The optical band gap, Eg4, found to increase with the addition of gallium. This variation is explained by the increase of the average bond energy that occurs with the addition of Ga into the alloys. The ... |
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| Photoelectret Properties and High-Field Polarization in Chalcogenide Glasses and Thin Films |
JUN 2001 |
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| Authors:
E. Skordeva; BULGARIAN ACADEMY OF SCIENCES SOFIA
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| The paper is dedicated to the 90th anniversary from the birth of my father, the late Prof. Razum Andreichin. It is dedicated also to the 2O% commemoration from the death of the Academician Georgy Nadjakov, the discoverer of the photelectret state (PES). A short historical review on the invention of PES is followed by a brief presentation of the matter of the photoelectret state and the high field polarization. The ... |
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| Spectroscopic Studies of Bulk As2S3 Glasses and Amorphous Films Doped with Dy, Sm and Mn |
JUN 2001 |
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| Authors:
M. S. Lovu; S. D. Shutov; A. M. Andriesh; E. I. Kamitsos; C. P. Varsamis; NATIONAL INST OF MATERIALS PHYSICS BUCHAREST (ROMANIA)
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| The effect of rare earth (Dy and Sm) and transition metal (Mn) luminescent impurities on the optical properties of As2S3 glass is studied in a wide spectra! region. The Raman, infrared, band-to-band and edge absorption spectroscopies are employed to obtain information about the incorporation of impurity ions in the host glass structure and the corresponding changes in intrinsic optical characteristics. The effects of light-soaking and thermal treatment on the doped ... |
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| Homogeneity Threshold in Sulphur Rich Ge-S Glasses |
JUN 2001 |
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| Authors:
Z. Cernosek; J. Holubova; E. Cernoskova; M. Frumar; PARDUBICE UNIV (CZECHOSLOVAKIA)
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| The glassy Ge-S system was analyzed on the basis of Raman spectra with the aim to find the compositional dependence of cyclo-octo-sulphur and polycatena sulphur. |
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| Thermal Properties of As-S Glasses in the Glass Transition Region |
JUN 2001 |
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| Authors:
E. Cernoskova; Z. Cernosek; J. Holubova; M. Frumar; PARDUBICE UNIV (CZECHOSLOVAKIA)
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| The compositional dependence of Tg, Cp and relaxation enthalpy in the glassy system As-S was investigated. The observed modifications are related to the change of coordination polyhedra. |
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| Carrier Type Reversal in Pb sub x Ge sub 42-x Se58 and Pb20Ge sub y Se sub 80-y Glasses Exhibited in Thermal Diffusivity Measurements |
JUN 2001 |
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| Authors:
R. Ganesan; B. Thangaraju; K. S. Sangunni; E. S. Gopal; INDIAN INST OF SCIENCE BANGALORE
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| Bulk Pb(x)Ge(42-x)Se(58)(x=0, 2.5, 5,7.5, 9, 10 &15 at.%) and Pb(20)Ge(y)Se(80-y) (y= 17, 19, 21, 23 and 25 at.%) homogeneous glasses have been prepared by melt quenching. The thermal diffusivity has been measured by the photoacoustic technique using a laboratory built non-resonant photoacoustic cell. The composition dependence of thermal diffusivity shows an anomalous behavior at x=9 at% of Pb in Pb(x)Ge(42-x)Se(58) and y=21 at% of Ge in Pb(20)Ge(y)Se(80-y)glasses, the composition at ... |
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| Photoconductivity and Transport Properties of As-Se Thin Films |
JUN 2001 |
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| Authors:
M. A. Iovu; M. S. Iovu; S. D. Shutov; E. P. Colomeyco; S. Z. Rebeja; MOLDOVA ACADEMY OF SCIENCES KISHINEV INST OF APPLIED PHYSICS
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| Steady-state and transient photo conductivity characteristics of thermally and laser-beam deposited chalcogenide amorphous films As40Se60 and As50Se50%0 are studied at varied light intensity and temperature. The lux-ampere characteristics are shown to change the power exponent from a value greater than 0.5 at low intensities to the value less than 0.5 at high intensities, indicating the change in recombination reaction. The transient photocurrents in step-function mode of excitation were found to ... |
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| Extended X-Ray Absorption Fine Structure Study on Bi Modified GeS Bulk Glasses |
JUN 2001 |
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| Authors:
G. Saffarini; J. M. Saiter; A. Zumailan; UNIVERSITE DE ROUEN CEDEX (FRANCE)
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| EXAFS measurements have been performed from the Ge K edge and Bi L(111) edge on GeSBi glasses with 6, 8 and 16 Bi at.%, and on crystalline Bi2S3. As expected, Ge is found to be fourfold coordinated with S atoms. It is also found that Bi is only coordinated with S with a coordination number CN-4. This result for the CN-4. of Bi contradicts the conclusion of Elliot and Steel. ... |
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| Correlation Between Mechanical Parameters for Amorphous Chalcogenide Films |
JUN 2001 |
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| Authors:
T. N. Shchurova; N. D. Savchenko; UZHGOROD NATIONAL UNIV (UKRAINE)
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| Young's modulus, linear thermal expansion coefficient, stress, microhardness, wear resistance, adhesion and cohesion strength for thin films of As2S3, As2Se3, Ge28Sb12Se60, Ge33As12Se55 and Ge36As4S60 chalcogenide glasses thermally deposited onto unheated zinc selenide substrates have been determined. The interrelationship between mechanical parameters of the films has been studied. Wear resistance of chalcogenide films has been found to be related to the adhesive force and mechanical parameters used in the formal theory ... |
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| New Chalcogenide Glasses in the GeSe2-As2Se3-CdTe System |
JUN 2001 |
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| Authors:
S. V. Boycheva; V. S. Vassilev; P. Petkov; UNIVERSITY OF CHEMICAL TECHNOLOGY AND METALLURGY SOFIA (BULGARIA) DEPT OF SEMICONDUCTORS
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| Glass-forming region in the GeSe2-As2Se3-CdTe system has been determined by visual, X-ray diffraction and electron microscope analyses. Glasses have been obtained in the GeSe2-rich region. Glass-formation has been situated wholly on the GeSe2- As2Se3 and partially on the GeSe2-CdTe and As2Se3-CdTe (0-15 Mol. % CdTe) sides in the Gibbs diagram. The maximal dissolution of CdTe in the glasses has been found up to 20 Mol. % CdTe. The temperatures of ... |
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| Ideas Concerning the Non-Crystalline Materials Obtainment by Melt undercooling |
JUN 2001 |
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| Authors:
P. Balta; UNIVERSITY OF POLITEHNICA BUCHAREST (ROMANIA)
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| A short selective review of concepts and ideas concerning the conditions in which the melts may be undercooled in vitreous state is presented. The important role of the cooling rate in the broadening of the glass forming domains, encouraging the apparition of the new ultra high cooling rate techniques, is underlined. Correlation between the undercooling in the vitreous state tendency and basicity (pB in %) is demonstrated. The new evidenced ... |
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| Possible High Temperature Superconductivity in Chalcogenide Glassy Semiconductors |
JUN 2001 |
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| Authors:
K. D. Tsendin; A. V. Prihodko; B. P. Popov; ANALYSIS DESIGN AND DIAGNOSTICS INC JACKSONVILLE FL
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| High Tc superconductivity in composite system of selenium matrix with globular Y-Ba-Cu-O is discussed in relation to the experimental results. |
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| Photosensitivity in Antimony Based Glasses |
JUN 2001 |
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| Authors:
M. Nalin; Y. Messaddeq; S. J. Ribeiro; M. Poulani; V. Briois; PARIS UNIV (FRANCE)
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| New glass forming systems based on Sb2O3-SbPO4 has been explored, These glasses present higher thermal stability against devitrification and higher refractive index than chalcogenide glasses. Under irradiation, using Ar-laser 350nm wavelength and 50 mW power density, change on the coloration is observed. Structural and electronic modifications around Sb cations induced by such treatment have been characterized by XANES measurements at the L-Sb edges. On the one hand, XANES spectra, at ... |
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| Thermo and Photoluminescence of Silicate Laser Glass Doped with Neodymium |
JUN 2001 |
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| Authors:
B. Grigoras; M. Cerscez; L. Ionescu; M. Secu; L. Matei; NATIONAL INST OF MATERIALS PHYSICS BUCHAREST (ROMANIA)
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| The luminescence and thermoluminescence have been measured in vitreous materials doped with Nd3+. The luminescence spectra show a maximum at 400 nm and a shoulder at about 440 nm. The measured global thermoluminescence shows a broad band with a maximum at 270 degrees centigrade, which suggests a continuous distribution of electron traps induced by ionizing radiation. Thermoluminescence measured through two optical filters which transmit at about 400 nm and 440 ... |
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| Reliable Ceramic Structural Composites Designed with Threshold Strength |
30 APR 2001 |
10 pages |
| Authors:
M. P. Rao; J. Roedel; F. F. Lange; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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 | A stress intensity (K) function describing the extension of a crack through bounding compressive layers has been experimentally verified using two methods. For one method the crack length was measured using a replicating technique; in the other, the crack length was continuously measured in-situ with an optical microscope during loading. In both, cracks were observed to propagate in a stable, nearly straight path across the compressive layer with increasing applied ... |
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| Reliable Ceramic Structural Composites Designed with a Threshold Strength |
30 APR 2001 |
19 pages |
| Authors:
Fred F. Lange; M. P. Rao; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| Compressive layers, placed within a laminate, can arrest cracks. With an increasing applied stress, the arrested crack can propagate through the compressive layer. These phenomena produce a material with a threshold strength, i.e., failure can not occur below a critical stress. A previously reported stress intensity function describes different variables, e.g., magnitude of compressive stress, thickness of compressive layer, distance between compressive layers, that govern the threshold strength. Laminar composites ... |
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| Reliable Ceramic Structural Composites Designed with a Threshold Strength |
30 APR 2001 |
22 pages |
| Authors:
Fred F. Lange; Kais Hbaieb; Robert M. McMeeking; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| Finite element analysis was carried out to predict the threshold strength of a laminar ceramics loaded parallel to the layers. These materials are composed of alternate layers of two different ceramics in which residual stress is generated. Strength limiting cracks are trapped by the compressive layers and require a minimum (threshold) applied stress to cause them to fail the laminated ceramic. The calculations were utilized to study the influence of ... |
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| Fundamental Mechanisms of Deformation and Fracture in High-Strength Bulk Metallic Glass Alloys and Their Composites |
APR 2001 |
14 pages |
| Authors:
Reinhold H. Dauskardt; STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The recent development of bulk metallic glasses (BMG's) offers the potential for metallic material systems with dramatically improved mechanical properties. Tensile strengths of 2 Gpa and toughnesses of up to 55 Mpav.m have been reported. These high strength and toughness values are accompanied by remarkably little plastic deformation. Until recently, little work has been undertaken to elucidate the fundamental deformation and fracture mechanisms of these alloys. This technical report describes ... |
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| Fracture Behavior of a Si3N4-BN Fibrous Monolith Ceramic |
APR 2001 |
204 pages |
| Authors:
J. L. Pierce; L. P. Zawada; J. M. Staehler; DAYTON UNIV OH STRUCTURAL INTEGRITY DIV
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| The two different microstructures of Si3N4-BN fibrous monolith ceramic material were compared to each other and to monolithic Si3N4 in order to evaluate the fracture behavior and effect of cell size on the mechanical performance of the material. The room temperature behavior was evaluated through fast-fracture tensile testing of straight-sided, dogbone, and modified single- edge notched specimens with various notch lengths. Load-unload and cyclic fracture tests were performed along with ... |
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| Deposition of Undercooled Liquid Ceramics |
24 MAR 2001 |
22 pages |
| Authors:
William Hofmeister; Joseph Wehrmeyer; VANDERBILT UNIV NASHVILLE TN DIV OF SPONSORED RESEARCH
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| The objective of the research is to show that ceramic particles can be melted in flight, undercooled in flight, and impacted on a substrate to form a thick film. It is further hypothesized that with adequate process control, deposits of high temperature ceramics can be created on heat sensitive substrates, e.g., hybrid electronic structures. The approach is to flow powders in a gas stream through a region of high photon ... |
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| Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications |
MAR 2001 |
40 pages |
| Authors:
Jeffrey J. Swab; Paul J. Huang; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC) as a part of a project entitled "Fighting Vehicle Propulsion Technology Using Ceramic Materials." Through research and exploratory development of advanced ceramics and other technologies, the objective of this project is to improve the mobility of future Army fighting ... |
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| Vacuum Furnance and Diamond Saw for Processing of Covalent Armor Ceramics and Composites |
MAR 2001 |
12 pages |
| Authors:
Vitali Nesterenko; CALIFORNIA UNIV REGENTS SAN DIEGO LA JOLLA CA
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| The grant from Defense University Research Instrumentation Program was used to purchase and install diamond wire saw and vacuum furnace at Advanced Powder Processing Lab at MAE Department, UCSD. The installation of this equipment added very important components to the existing equipment at Advanced Powder Processing Lab at MAE Department, UCSD which now has Hot isostatic Pressing unit, Warm and Cold Isostatic Pressing units, 2 vacuum furnaces (low and high ... |
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| Synthesis of Intermetallics and Ceramics With Ultra-Fine Microstructures |
21 FEB 2001 |
87 pages |
| Authors:
Naresh N. Thadhani; GEORGIA INST OF TECH ATLANTA SCHOOL OFMATERIALS SCIENCE AND ENGINEERING
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| The objective of our work has been to combine the beneficial effects of shock-compression of powders and solid-state structural and chemical changes for synthesis and fabrication of intermetallic alloys and ceramics with ultra- fine-grain microstructures. In particular, our research has focussed on studying the mechanisms and kinetics of shock-induced chemical reactions using simultaneous time-resolved stress and velocity measurements combined with shock recovery experiments. The possible shock-induced formation of otherwise difficult-to-synthesize ... |
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| Embedded Heat Pipes in Ceramic Electronic Packages and Filling Process |
FEB 2001 |
46 pages |
| Authors:
K. Jones; Y. Cao; M. Gao; FLORIDA INTERNATIONAL UNIV MIAMI DEPT OF MECHANICAL ENGINEERING
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| The development of a new technology for electronic cooling is described in this report. By integrating heat pipes directly within the ceramic substrate, effective thermal conduction for spreading heat in both radial and axial directions was achieved. Several prototype miniature heat pipes have been fabricated in HTCC and LTCC substrates in the Hybrid Lab at FTU using numerically controlled machining operations. The heat pipes use an axially grooved wick structure ... |
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| Mechanics of Powder Plastic Powder Compacts |
10 JAN 2001 |
51 pages |
| Authors:
Fred F. Lange; CALIFORNIA UNIV SANTA BARBARA COLL OF ENGINEERING
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| Colloidal Isopressing is a new method for the shaping of ceramic components from powder suspensions in a rapid and effective manner. Colloidal Isopressing starts with a slurry containing a relatively low volume fraction of powder, where the particles weakly attracted to one another due to a short-range repulsive potential developed during slurry formulation. The slurry is pre- consolidated to a high relative density at a pressure that will allow the ... |
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| Dynamic and Quasi-Static Multiaxial Response of Ceramics and Constitutive/Damage Modeling |
02 JAN 2001 |
15 pages |
| Authors:
Akhtar S. Khan; MARYLAND UNIV BALTIMORE COUNTY BALTIMORE MD
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| Acoustic emission (AE) waveforms were recorded during compression of the ceramic Alumina AD995. The frequency contents of the wave form were determined using FFT technique. It was found that signals which represented damage/crack growth had frequencies between 39 and 80 kHz. Experiments were also performed on post-shocked AD995 specimens. Significant differences were observed which demonstrated that AE technique could be used for damage evolution determination. |
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| Templated Grain Growth of Single Crystal-Like Electroceramics |
JAN 2001 |
52 pages |
| Authors:
Gary L. Messing; Susan Trolier-McKinstry; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
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| Fiber textured bismuth titanate (Bi4Ti3O12) (BIT) and biaxially textured La-doped Sr2Nb2O7 (SN) were produced by templated grain growth. Platelets of BIT and blade-shaped SN template particles were dispersed in a matrix of nanosize BIT and fine SN powders, respectively. and aligned by tape casting. As determined by x-ray diffraction and microscopy. the sintered ceramics were >90% textured. Growth of the template particles depends critically on the presence of a liquid ... |
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| Off-the-Shelf Antifreeze Admixture for Concrete Initial Laboratory Investigation |
JAN 2001 |
23 pages |
| Authors:
Charles J. Korhonen; Sherri A. Orchino; ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
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| Set-controlling and water-reducing admixtures conforming to ASTM C 494 were studied for their effect on strength gain of portland cement concrete at below-freezing temperatures. Because standard practice does not limit the number of admixtures that can be used in concrete, the objective was to use as many admixtures as necessary to depress the freezing point of the mix water to - 5 deg C (23 deg F) or below and ... |
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| Will Pigs Fly before Ceramics Do |
JAN 2001 |
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| Authors:
Lisa C. Veitch; William S. Hong; INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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| The objective of the IDA study was to assess the feasibility of using current technology ceramic rotating components in an advanced turbofan engine core, to determine the associated risks of doing so, and to identify and recommend materials development activities which would best address those risks. Both monolithic and ceramic matrix composites (CMC) materials were considered, and the study also took into consideration the use of ceramics in adjoining static ... |
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| Processing Multi-Phase Ceramic Composites for Vehicular Survivability |
2001 |
3 pages |
| Authors:
L. P. Franks; J. W. Adams; G. A. Gilde; E. S. Chin; ARMY TANK-AUTOMOTIVE AND ARMAMENTS COMMAND WARREN MI
|
| In the past, the most capable armor was heavy and developed for main battle tanks weighing 50 tons or more. The increasingly changing state of global politics requires rapid deployment of a military force anywhere in the world. Rapid deployment dictates that the best armor be available for lightweight military vehicles. The urgency to deploy Army's Future Combat System has challenged the armor materials community to employ non-traditional materials to ... |
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| Photoinduced Optical Effects in BiB3O6 Glass |
2001 |
5 pages |
| Authors:
I. V. Kityk; M. Makowska-Janusik; A. Majchrowski; MILITARY UNIV OF TECHNOLOGY KALISKIEGO(POLAND) INST OF APPLIED PHYSICS
|
| A new borate material, BiB3O6 (BiBO), has been reported to have extremely high nonlinear optical (NLO) coefficient. In our investigations we obtained both glass and single crystals of BiBO. Owing to its composition, the material is very viscous when molten. This factor causes serious problems both during synthesis and crystallization of BiBO. In this paper only properties of BiBO glass are reported. We found that for the increase of the ... |
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| Excited State Absorption of the Cr(6+)O(2-) Center in Li2B4O7 Glass |
2001 |
4 pages |
| Authors:
Czeslaw Koepke; Krzysztof Wisniewski; Marek Grinberg; NICHOLAS COPERNICUS UNIV OF TORUN (POLAND) INST OF PHYSICS
|
| We present excited state absorption (ESA) measurements of the Cr:Li2B4O7 glass (Cr:LBO-glass) along with preliminary interpretation. The most distinct feature in the ESA characteristics is connected with the presence of chromium in its hexe-(d(sup 0)) valence states. The Cr(6+) ions appear to contribute in the deexcitation processes and their evidence can be seen in the ESA spectra under excitation wavelength at 308 nm. We interpret the ESA spectra detected with ... |
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| Optical Hole Burning Studies in Glasses Doped with Dyes and Rare-Earth Ions |
28 NOV 2000 |
89 pages |
| Authors:
B. R. Reddy; Anshel Gorokhovsky; ALABAMA A AND M UNIV NORMAL DEPT OF PHYSICS
|
| Rare-earth ion doped glasses and dye doped sol-gel glasses and spin- coated polymers were prepared and investigated by optical methods at room and liquid helium temperatures. Eu3+ glasses revealed large inhomogeneous broadenings (3-6 nm) and these samples also exhibited transient spectral hole burning at cryogenic temperatures. Hole burning studies in Eu3+ doped YSO and CaF2 revealed more than 40 sites for the dopants. These were due to clustering of the ... |
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| Ion and Neutral Dynamics of Ceramic Materials Formation and Atmospheric Chemistry |
27 NOV 2000 |
20 pages |
| Authors:
Stephen R. Leone; Veronica M. Bierbaum; COLORADO UNIV AT BOULDER
|
| An ultrafast x-ray laser system and experimental apparatus have been fully constructed, calibrated and characterized. A titanium sapphire ultrafast laser is tightly focused into a rare gas jet, where high harmonics of the laser are created. A single harmonic can be isolated with a grazing-incidence grating and focused on to a gaseous sample to induce photoionization. Ejected electrons are energy analyzed using a magnetic bottle time-of-flight spectrometer. Harmonics up to ... |
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| Development of Statewide Portland Cement Patching Products and Procedures |
16 NOV 2000 |
153 pages |
| Authors:
Robert I. Bartlow Jr.; OKLAHOMA UNIV NORMAN DEPT OF CIVIL ENGINEERING
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| An investigation was performed to develop concrete mixtures capable of developing high early strength combined with relatively low shrinkage characteristics, good bonding characteristics and generally good compatibility with existing substrate and surrounding media. These concrete mixtures are intended for patching of portland cement rigid pavement and bridge decks. This investigation consists of two parts, an Investigation in the field and an investigation in the ... |
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| Japan-America Frontiers of Engineering Symposium 2000 |
04 NOV 2000 |
69 pages |
| Authors:
NATIONAL ACADEMY OF ENGINEERING WASHINGTON DC
|
| On November 2%, 2000, 60 outstanding Japanese and American engineers from industry, academia, government labs, and other research institutions gathered for the First Japan-America Frontiers of Engineering Symposium (JAFOE) in Nara, Japan. Convened by the U.S. National Academy of Engineering (NAE), the Engineering Academy of Japan (EAJ), and the Japan Science and Technology Corporation (JST), this exciting and unique meeting included presentations and discussion of leading-edge research and technical work ... |
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| Finishing of Advanced Ceramics |
30 OCT 2000 |
158 pages |
| Authors:
Ranga Komanduri; OKLAHOMA STATE UNIV STILLWATER SCHOOL OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This project deals with both fundamental and applied aspects of finishing of advanced ceramics, such as silicon nitride (Si3N4) balls for hybrid bearing applications using the magnetic float polishing (MFP) technology developed under DARPA's Ceramic Bearing Technology Program (CF 33615-92-C-5933). On the fundamental side, an understanding of the material removal mechanisms involving both mechanical and chemo-mechanical polishing (CMP) as well as thermal aspects of polishing were ... |
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| Interface Chemical Modification for Property Control of Oxide ReinforcedCeramic Matrix Composites |
13 OCT 2000 |
16 pages |
| Authors:
Dawn A. Bonnell; PENNSYLVANIA UNIV PHILADELPHIA BOARD OF TRUSTEES
|
| The Air Force requirements for high temperature structural materials include applications in aircraft afterburner and in propulsion systems. Ceramic matrix composites are candidate materials systems for several types of these applications. In the effort to develop composites for high temperature structural applications attention has turned towards oxide-oxide systems. The objective of this project is to systematically investigate the segregation behavior and high temperature stability ... |
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| The 4th International Conference on Fracture and Strength of Solids Heldin Pohang, Korea, on 16-18 August 2000. Part 2 - Behavior of Materials and Structure |
01 SEP 2000 |
708 pages |
| Authors:
W. Hwang; K. S. Han; POHANG INST OF SCIENCE AND TECHNOLOGY (REPUBLIC OF KOREA)
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| Part 1: Fracture Mechanics of Materials. Includes: Fracture Mechanics; Dynamic Fracture; Computational Mechanics; and Damage Mechanics. (678 Pages) Part II: Behavior of Materials and Structure: Includes: Fracture Physics; Fatigue and Creep; Polymer and Polymer Composites; Metals, MMCs, Ceramics, and CMCs; and Welding. (672 Pages) |
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| The 4th International Conference on Fracture and Strength of Solids Heldin Pohang, Korea, on 16-18 August 2000. Part 1 - Fracture Mechanics of Materials |
01 SEP 2000 |
718 pages |
| Authors:
W. Hwang; K. S. Han; POHANG INST OF SCIENCE AND TECHNOLOGY (REPUBLIC OF KOREA)
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| Part I: Fracture Mechanics of Materials. Includes: Fracture Mechanics; Dynamic Fracture; Computational Mechanics; and Damage Mechanics. (678 Pages) Part II: Behavior of Materials and Structure: Includes: Fracture Physics; Fatigue and Creep; Polymer and Polymer Composites; Metals. MMCs, Ceramics, and CMCs; and Welding. (672 Pages) |
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| An Assessment of Smart Air and Space Structures: Demonstrations and Technology |
SEP 2000 |
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| Authors:
Alok Das; Janet M. Sater; C. R. Crowe; Richard Antcliff; INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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| During the past decade, the multidisciplinary field of smart materials and structures has experienced rapid growth in terms of individual technologies and applications. The integration of sensors, actuators, and controllers with structures that enable adaptation to environmental and operational conditions has progressed to such a point that numerous systems applications are being demonstrated. This paper reviews the current status, results to date, and issues ... |
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| Novel Electroceramic Materials and Integrated Devices |
AUG 2000 |
18 pages |
| Authors:
Ram S. Katiyar; PUERTO RICO UNIV SAN JUAN
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| A number of Perovskites have been grown and their properities analyzed under the general field of 'Novel Electroceramic Materials and Integrated Devices'. Besides their structural properties, their electrical and optical properties were investigated. These investigations were published in ten papers that have appeared in scientific journals. |
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Ceramics, Refractories and Glass
