Professor Robert W. Balluffi has studies underway on the structure and electrical properties of grain boundaries in ZnO. Bicrystals of ZnO of controlled geometry have been prepared and techniques for doping the grain boundaries with Bi, Pr, Co and Ni solute atoms are being developed. The results should increase our understanding of the varistor behavior of polycrystalline ZnO doped with these solute atoms.
Professor Gerbrand Ceder has made significant progress towards the accurate computation of oxide phase diagrams. His first-principles computation of the CaO-MgO phase diagram is in almost perfect agreement with experimental data. In this iso-valent cation system the variation in the size of the oxygen ion with electrostatic field was found to be an important factor in accurately reproducing the solid solubility limits. Together with the multi-component disorder formalism he developed last year, he now has the essential ingredients for a first-principles theory of ordered and disordered oxide systems. In the fast ion conductor ß-alumina, he identified the importance of Mg-Al ordering for the mobility of Na in the material. This new insight has allowed him to reinterpret twenty years worth of literature on the subject.
During 1994, Professor Yet-Ming Chiang led a new Interdisciplinary Research Group formed with MIT's NSF/MRSEC program to study the interrelationship between atomic-level structure, chemistry, and transport properties of oxide interfaces important in electrical and chemical functions. Specific results by Professor Chiang on the ZnO-Bi2O3 varistor system show that interfacial segregation in a simple two-phase polycrystal can be controlled by many mechanisms. New behavior has been discovered in which weak capillary pressures (~1 MPa) in the solid-liquid regime as well as high applied pressures (~1 GPa) in solid-solid equilibrium can have a controlling influence on the segregation of electrically active Bi solute to ZnO grain boundaries. A new program has been initiated in net-shape processing of ceramic-ceramic and ceramic-metal composites by reactive infiltration, sponsored by the Office of Naval Research. Reaction-infiltrated composites in the SiC-Al and SiC-Cu systems have been demonstrated with dimensional changes of less than 0.1% from the starting green compact. Professors Chiang's collaboration with Professor Joel P. Clark in the cost-modeling of reaction forming processes is an integral component of this research. Professor Chaing has also initiated a research needs assessment for the U.S Department of Energy on the potential energy applications of nanostructured materials, in collaboration with Professor Jackie Y. Ying of the Chemical Engineering Department and the Energy Lab at MIT.
Professor Joel P. Clark has established a major research program in Life Cycle Analysis (LCA) of automotive materials and products, working with most of the automotive assemblers in the U.S. Europe and Japan. This LCA framework is being used to analyze the costs and highlights of: (1) substituting light weight (e.g., aluminum and polymer composite designs) structures for steel, (2) electric vehicles vs. low emissions IC vehicles, and (3) recycling technologies and policies.
Professor David C. Dunand's research in metallurgy focuses on high-temperature, high-strength alloys, intermetallics and composites. His group is investigating the superplasticity and recrystallization of metal matrix composites; the high temperature deformation of dispersion-strengthened aluminum and intermetallics; the mechanisms of creep in fiber-reinforced intermetallics; and the physical and mechanical behavior of particle-reinforced intermetallic NiTi shape-memory alloys.
During the past year, Professor Thomas W. Eagar has developed the first dynamic model of droplet detachment during gas metal arc welding. This model incorporates the effects of surface tension and electromagnetic forces in a comprehensive description of the various modes of metal transfer during arc welding. He has also demonstrated a new variation of diffusion bonding which is capable of producing thick joints in advanced alloys and intermetallics. This process which has been named Liquid Infiltration Powder Bonding (LIPB) uses a powder interlayer of base metal composition which is infiltrated with a liquid forming a fully dense liquid phase sintered structure. The elimination of all porosity in thick joints makes this a significant improvement over previous processes.
This year Professor Eugene A. Fitzgerald's work concentrated on the improvement of UHVCVD growth of relaxed GeSi/Si structures for GeSi/Si IR detectors, GeSi/Si Field Effect Transistors and III-V Integration. He has discovered that the electrical properties of the dislocations in the relaxed graded GeSi layer are extremely sensitive to growth temperature. Low temperature growth (650[[ring]]C) results in p-type point defect production, whereas high temperature (900[[ring]]C) structures show the intrinsic n-type background. These results improve our ability to estimate the effect of threading dislocations on FET and detector performance.
Dr. John Haggerty's current research focuses on the processing and properties of monolithic and composite ceramics made from high purity ceramic powders and polymeric precursors. Additionally, he has initiated research programs in growth of oxide single crystals for use as reinforcements of metal and ceramic matrix composites and as high TC superconductors.
Professor Linn W. Hobbs has continued with his studies in the H.H. Uhlig Corrosion Laboratory of high-temperature oxidation and sulfidation of metal alloys. NSF-supported acquisition of kinetic data for oxidation-sulfidation of a range of Cr-Nb and Fe-Cr-Nb alloys in H2-H2O-H2S gas mixtures has confirmed earlier static oxidation and static sulfidation results on Nb-45wt%Cr. The measurements show that the pure sulfidation resistance of the Nb-45wt%Cr composition almost equals that of pure Nb, while the corrosion resistance Cr-40wt%Nb is somewhat poorer in pure sulfidation, though much better than Cr alone, and close to that of Cr in pure oxidation and in oxidation-sulfidation. A patent application has been granted for the Nb-Cr alloy compositions exhibiting corrosion resistance over an unprecedented range of oxygen and sulfur partial pressures. Professor Lionel C. Kimerling's silicon microphotonics program developed a process simulator for the Si:Er-F system to yield a demonstrated x100 increase in luminescence intensity. He has fabricated a one dimensional Photonic Band Gap structure consisting of Si/SiO2/air dielectrics, and used it to demonstrate photon coupling into a silicon waveguide and photon scattering for energies greater than the structure's photonic band gap. He has also developed a thermodynamic model based on Pourbaix diagrams to define the phase fields (pH vs. oxidation potential) for metal adsorption on silicon surfaces from standard cleaning solutions.
Professor Kirk Kolenbrander's greatest success in 1994 was his development of a silicon nanocrystallite solid state electroluminescent light emitting device. This room temperature device emits visible (orange-red) light, and appears to be indefinitely stable. The device combines his semiconductor nanocrystallite synthesis and processing capabilities with thin film conducting polymers to yield a unique polymer/semiconductor heterostructure. These efforts on the electroluminescence of silicon nancrystallites are a part of his more general effort on exploring the luminescence mechanisms available to quantum confined silicon nanocrystallites.
Professor Ronald M. Latanision is engaged in a DOD (US Army) University Research Initiative oriented toward the destruction of chemical waste by means of supercritical water oxidation. This dual-use technology applies to both civilian and military wastes. Chlorinated feed streams are found to be particularly troublesome and lead to accelerated wastage as well as to stress corrosion cracking in materials such as Inconel 625 and Hastelloy C-276, both typically very corrosion resistant alloys.
Professor Heather N. Lechtman continues her research in the field of prehistoric technologies of the Andean culture area, with an emphasis on the early metallurgies of those societies. She is currently investigating the properties of Cu-As alloys and the prehistoric smelting regimes used to win copper-arsenic bronze from Andean tetrahedrite ores.
Professor Anne M. Mayes has recently completed the construction of a state-of-the-art x-ray reflectometer, built off a dedicated port of an 18kw rotating anode generator in the CMSE X-ray Analysis Facility. This highly versatile instrument will serve as a principal tool for surface/interface investigations by her group and by others in the MIT materials community. The intrinsic horizontal geometry of the instrument will allow for liquid surface investigations, while a more conventional vertical geometry is easily adopted for the study of solid films. She has performed investigations on the first known block copolymer to exhibit an ordering transition with increasing temperature. The rheological and scattering properties of the high temperature ordered phase of poly(styrene-b-n-butyl methacrylate) are observed to be analogous to those of block copolymers which order with decreasing temperature. In the ordered state, the locally segregated copolymer blocks act as "thermodynamic crosslinks," inhibiting macroscopic flow of the polymer. Professor Frederick J. McGarry developed and validated a method to predict certain types of cracking in electronic packages, and developed a new technique for adhesives testing.
The past year has been a year of progress in several projects for Professor Andreas Mortensen with the completion of a project on reinforcement architecture on thermal expansion of reinforced metals, a problem of significant practical importance in electronic packaging applications of these materials. Achievements of this past year in micromechanical studies of reinforced metals have comprised (i) the final development of a technique for imaging and measuring stress and strain distributions within the bulk of microscopic elastoplastic materials, with a focus on micromechanics of two-phase alloys, and (ii) the development of a method for producing pore-free silver-chloride samples for dislocation decoration under stress.
Dr. O'Handley's new data shows for the first time that magnetoelastic coupling in polycrystalline thin films differs from that of bulk material by the addition of a term proportional to inverse film thickness. Subsequently, two other groups have reported similar findings. He has shown that the same effect must be present in single crystal, epitaxial Cu/Ni/Cu films.
Professor Uday B. Pal has designed and developed a novel electrochemical device (made of conducting ceramic oxides) for inclusion free refining of molten metals. The device operates as a current producing galvanic cell. The refining process with the device has been modeled and optimized. A scale-up trial of the process with a prototype of the device, which will be supplied by Norton Corporation, will be conducted at Reading Tube Corporation. Based on his work on the elucidation of the role of electrochemical transport in FeO containing slags during recarburization of suspended iron droplets he has designed an environmentally sound method and apparatus for enhancing reaction rates in metals extraction, refining and recycling operations involving ionic melts like slags, mattes, and fluxes. Briefly, it involves application of an electric potential and/or the formation of an electronic pathway across the ionic melt through the use of plasma or electric arcs. A patent has been filed and industrial scale trials will be conducted in the coming year.
Professor David I. Paul analyzed the temperature dependence of the magnetization reversal process in thin film and granular ferromagnetic materials, continued work on the "phase transition" for magnetic reversal mechanism and hysteresis as a function of the magnetic anisotropy sample size, and temperature. Professor Regis M. N. Pelloux's research work is centered around the study of the mechanical behavior of fatigue, creep, and fracture of advanced engineering alloys. His research on the aging of aircraft fuselage structures led to measurements of the fatigue crack growth rates in thin gauge aluminum alloys as a function of frequency and stress level in a corrosive environment, which is key to improved prediction methodology.
Professor Robert M. Rose had two major developments in his research work this past year, (1) elastic radiation (magnetacoustic emission) was predicted for accelerating 180[[ring]] domain walls in magnetic materials, and (2) electropexis was predicted theoretically for polar liquids in high electric fields, and confirmed for pure water by the use of a modified scanning tunneling microscope. Professor Roylance's research has centered on process - structure - property investigations of polymers and composite materials, dealing especially with mechanical properties. Among these topics have been the durability of filled elastomers subjected to large cyclic loads, the role of chain extension versus crosslinking in high-temperature polymer matrix resins, the role of processing variables on the morphology and properties of toughened polyamide resins, the modeling of flow and heat transfer during infiltration processing of composites, and the response of ultraoriented fibers to high-speed impact.
Professor Kenneth C. Russell has developed a theory for the unusual nucleation processes which occur in such non-equilibrium materials as fine-scale nanostructures in vapor deposited thin films, in mechanically alloyed metals, and in alloys under irradiation. The theory has been successfully applied to ion mixing in thin film deposition and irradiation-induced pressure vessel embrittlement in light water reactors. He has successfully analyzed the thermodynamics and kinetics of bubble formation and growth in controlled porosity alloys. Conditions for bubble nucleation and coupled eutectic zone growth have been derived.
Professor Donald R. Sadoway received certification of a new apparatus for measuring the electrical conductivity of liquids. He has now demonstrated its capabilities both with aqueous KCl solutions at room temperature and this past year with molten KCl and KNO3. All the active parts of the cell are made of metal, not dielectric material; thus, the apparatus can measure the electrical properties of highly aggressive liquids at temperatures exceeding 2000[[ring]]C.
Professor Chris E. Scott's work on the compounding of low viscosity, immiscible fluids with polymeric matrices involves using a model system to investigate of the processing behavior of formulations involving compounding of a low viscosity, immiscible additive into a polymer matrix. The model systems consist of a series of different molecular weight polyethylene waxes in polystyrene. The melting behavior during compounding is dependent on the molecular weight, and thus the melt viscosity, of the polyethylene. A critical polyethylene molecular weight exists, below which the softening (melting) of the polystyrene, and thus mixing of the two components, is greatly retarded.
Professor Subra Suresh developed a new analytical model for predicting the plastic response of multi-layered materials and a new constitutive formulations, computational tools and engineering diagrams for modelling and designing for the mechanical response of graded materials. He was co-developer, of MuliTherm, a software for analyzing the thermomechanical response of layered and graded materials using a personal computer. This software is now licensed by the Technology Licensing Office at MIT.
Professor Julian Szekely developed a mathematical model of bump soldering operations and this model is now being used as part of a major R&D effort by AT&T. He has also developed a mathematical representation of droplet oscillation in microgravity. These results were used in a space shuttle flight in 1994.
Professor Edwin L. Thomas' roll casting process has been utilized to produce near-single-crystal-like materials of hexagonally packed cylindrical domains in triblock A/B/A polystyrene-polybutadiene-polystyrene copolymers. The microstructural changes accompanying the large strain deformation behavior are being investigated by a combination of TEM and SAXS of deforming samples at the National Synchotron Light Source (NSLS) at Brookhaven, NY. These studies have revealed a heretofore un-resolved (spatially and temporally) wealth of information concerning the details of how the applied strain influences the rubber matrix and the glassy polystyrene cylinders. A mechanical instability analysis of the axially compressed cylinders provides an excellent description for deformation normal to the cylinder axis.
Professor Carl V. Thompson has developed analytic models and computer simulations of the effects of strain on grain growth and texture evolution in polycrystalline thin films. The crystallographic texture resulting in experiments on grain growth in thin films has been shown to be a predictable function of the deposition temperature and the film thickness. He has developed the ability to create single crystal aluminum thin film electromigration test structures on oxidized Si wafers. This has allowed him to characterize transgranular electromigration failure mechanisms in isolation from other failure mechanisms.
Professor Harry L. Tuller investigated single electrically active grain boundaries in ZnO, developed processing "tools" for photoassisted micromachining of silicon, and continued development of the science and technology of pyrochlore compounds for use in solid oxide fuel cells.
Professor August F. Witt directed his efforts at exploring the potential of reduced gravity environment for research concerned with property control during growth of opto-electronic materials (BSO: Bi12SiO20), focus was placed on the development of non-invasive property analysis. In his NASA sponsored research a method was developed which results in self-decoration of dislocations in BSO and permits (for the first time) their direct observation in conventional (polarized light) transmission microscopy. Professor Wuensch has synthesized isolated tilt boundaries of controlled geometry in ultra pure bicrystals of MgO and NiO. Chemical vapor transport with HC1 was used to deposit epitaxial or heteroepitaxial NiO specimens with neutron activation analysis and mass spectrometry showed the content of all impurities to be below the level of their detectability (typically 10ppm).
Andrew Y. Kim was invited to join Phi Beta Kappa. The spring initiates for The Tau Beta Pi Engineering Honor Society were: Paul S. Minson, Pradeep R. Sreekanthan and Benjamin C. Yu. The fall initiates were: John Guzek, Uday Jhunjhunwala, Sandra K. Joung, Erin B. Lavik, Julie Ngau, and Benjamin C. Yu.
Six seniors were accepted as associate members in the Society of Sigma Xi, The Scientific Research Society of North America: Sandra Joung, Andrew Kim, Erin Lavik, Cynthia Mowery, Julie Ngau, and Benjamin Wu.
Andrew P. Phelps '95 was awarded The Admiral Edward L. Cochrane Award, presented annually to a male senior who has shown the highest qualities of humility, leadership, and inspiration in intercollegiate athletics. The Program in Polymer Science and Technology (PPST) held its first annual student poster session contest in February, 1995. Industrial sponsor Hoechst-Celanese offered cash prizes for the best four posters on a polymer-related research topic. Fifteen posters were entered in the contest by studetns from five different departments at MIT. Seven Materials Science and Engineering students participated, and the research groups of Professors Cebe, Mayes, Rubner and Thomas were represented. Orhun Muratoglu, a Course III/PPST student working ofr Professor Robert Cohen of Chemical Engineering, won the $500 first prize for his poster, " Microstructural Fracture Processes Accompanying Growing Cracks in Tough Rubber Modified Polyamides." Thomas Schaub, a Course III student in Professor Mayes' group, won second prize for his poster "Chain End Segregation Studies in Thin Film Polymer Systems," and John Chen, of Professor Thomas' group, won one of two third prizes for his poster, "A Study of the Optical Waveguiding Properties of Polymer and Block Copolymer Thin Films." Dr. Rich Straff of Hoechst-Celanese, a Course III graduate, served as judge. Surekha Vajjhala, a junior in Course III, is one of 16 students in the country to win the Beinecke Memorial Scholarship, which awards $32,000 for graduate study. Candidates are considered for strength of character, intellectual ability, sense of purpose, creativity and leadership. Ms. Vajjhala went through an internal selection process and was selected as MIT's nominee this year, the first in which MIT was invited to submit a nominee. She will use the award to fund medical school, which she hopes to begin in 1996.
Seven graduate students were accepted as associate members in the Society of Sigma Xi: Y.-K. Chiang, Marcos G. Fernandes, James Foresi, Robert Hyers, Yingchung Liu, Ren-Kae Shiue, and Arvind Sundarrajan. Six graduate students were accepted as full members: Roland Carel, Andrew C.-S. Chen, Katherine Chen, Filippos Patsiogiannis, Hua Shen, and Shi Yuan.
Ali Farah was accepted in the Scholarship Program of King Faisal Foundation for the Ph.D. degree in materials science. Julie Tsai, one of Professor Rafael Reif's graduate students, received an "Outstanding Research Presentation: award for a presentation she gave at the eighth annual Graduate Fellowship Program Annual Conference held in North Carolina this past November. The award-winning presentation was entitled, "Polycrystalline Silicon-Germanium Alloys for Thin-Film Transistor Applications."
Fellowship Awards for one or more semester were held during academic year 1994-1995 by 44 students: Adrian F. Kohan, David V. Ragone Fellowship, Class of '39 Fellowship and the Gilbert Y. Chin Fellowship; David G. Walton, The Lord Foundation Fellowship; Robert W. Hyers, NASA Fellowship; Naomi A. Fried, NASA Space Grant Fellowship; Darren T. Castro, NDSEG Fellowship; Brian J. Gally, NDSEG Fellowship; Arun A. Seraphin, NDSEG Fellowship; Luis D. German, Roberto Rocca Fellowship; Julia A. Tsai, SRC Fellowship; F. Patsiogiannis, SIDOR Fellowship; Peter Zwigl, SIDOR Fellowship; Ann M. Redsten, SIDOR Fellowship; Stephen C. Britten, Starr Foundation Fellowship; Yorl Fink, Starr Foundation Fellowship; Philip P. Soo, Starr Foundation Fellowship; Matthieu Rolland, 3M Fellowship; Charles W. Rowe, 3M Fellowship; Laura M. Giovane, 3M Fellowship; Robert Calhoun, Loeb Fellowship; Janelle Greer, US Air Force Fellowship; and Ramabhadra Ratnagiri, John F. Elliott Fellowship. Adam Powell, AT&T Coop Research Fellowship; Scott E. Deering, AT&T Coop Research Fellowship; Michael T. Morse, AT&T Bell School Program Fellowship; Eric Werwa, AT&T Bell School Program Fellowship; James E. Neely III, DOE Fellowship; Jeffrey Nystrom, DOE Fellowship; Stephen Britten, NDSEG Fellowship; Tracey Burr, NDSEG Fellowship; Edison C. Chu, NDSEG Fellowship; Jason Gratt, NDSEG Fellowship; Oliveria E. Kesler, NDSEG Fellowship; Lynn Calfoun, NSF Fellowship; David W. Pratt, NSF Fellowship; Vanessa Z.-H. Chan, NSF Fellowship; Benita J. Dair, NSF Fellowship; Michael F. Durstock, NSF Fellowship; Randolph Kirchain, Jr., NSF Fellowship; Martin L. Panchula, NSF Fellowship; Michael J. Fasolka, NSF Fellowship; Erika Abbas, ONR Fellowship; Valerie Benezra, ONR Fellowship; Kevin W. Eberman, ONR Fellowship; Alice M. Man, ONR Fellowship; and Isako Hoshino, AT&T Bell Labs Fellowship;
Challenges for the future include the completion of our textbook initiative, the revamping of our graduate curriculum and the general re-engineering of our research programs to fit with the ever-changing sources of research funding. In this latter area, I believe we will need to be much more attentive to the needs of our sponsors, while maintaining the academic rigor and educational opportunities for our students. The hardening of the faculty salaries by the MIT administration and the significant number of the graduate fellowships raised primarily by Professor Flemings provide us with a firm base to approach these changing times. Nonetheless, the needs of our students and their potential for initial employment will require changing attitudes, educational curriculum and research modes on the part of our faculty members. During the coming fall, we expect to initiate a long-range planning exercise to help develop consensus about the ways in which we must change to meet these new challenges while maintaining the academic excellence which has brought us to where we are today.
A particular concern, is the difficulty with which young faculty face the raising of research funds. This may require a shift from the somewhat entrepreneurial, individualistic approach, which has served this Department so well for the past 30 years, to a model involving significantly more interaction and cooperation between groups of faculty members. Currently, I believe the faculty of the Department recognize the need for change, but they are still in the process of determining what form the change will take. Given the quality of the faculty which we have and their commitment to excellence in education and research, I have no doubt that we will evolve a new model for continuation of our current education and research in the future.
Thomas W. Eagar
MIT Reports to the President 1994-95