MIT has an extraordinarily strong and broad effort in materials science and engineering involving approximately 110 faculty members in 11 departments in the schools of science and engineering. There is great opportunity in this environment to solve problems that address the needs of society more effectively by encouraging collaboration. Thus, CMSE has a special mission: to foster collaborative interdisciplinary research and education in the fundamental science of materials and in the engineering of materials for specific applications. CMSE not only promotes collaboration among MIT faculty trained in different disciplines, but also between MIT researchers and the researchers of other universities, industry, and government and nonprofit laboratories.
Collaborative research is encouraged through several mechanisms: interdisciplinary research groups (IRGs), shared experimental facilities (SEFs), infrastructure enhancement, and outreach programs. The IRGs, described below, are composed of MIT faculty who, with their students and postdoctoral associates, wish to investigate fundamental scientific questions and pathways to reach significant technological goals that can only be properly explored in a collaborative, multidisciplinary mode. These problems are too large in scope to be addressed by individual faculty members and their students. Collaboration is essential for materials-related science and engineering, even for individual investigators, because such research requires very sophisticated equipment and infrastructure. CMSE provides a mechanism for the purchase and supervision of such equipment in its SEFs. The equipment is made available to the members of the IRGs, individual MIT investigators, and researchers from other university, industrial, government, and nonprofit laboratories. In these facilities, students, postdoctoral associates, and industrial researchers working on different topics intermingle and transfer expertise and technology across traditional disciplinary boundaries. CMSE also supervises the operation, maintenance, and improvement of the Vannevar Bush building, thus providing the infrastructure necessary for first class materials research. Researchers from four departments are intermixed in the building, facilitating interdisciplinary cooperation.
CMSE also provides seed and initiative funds. While preference is given to young faculty, CMSE uses seed funds to support research that has the potential of redefining the direction of an existing IRG or leading to the creation of a completely new IRG. Seed funding provides CMSE with the flexibility necessary to initiate high-risk research. During the past year CMSE held its second open competition for seed grants. Eight seeds are now supported. In addition, 14 faculty are active in three initiatives, which are groups of faculty that may become new IRGs.
The purpose of this program is to explore the fundamental nature, synthesis, and properties of Photonic Band Gap (PBG) materials and to exploit these properties for the creation and control of electromagnetic radiation. These materials are a composite of a periodic array of macroscopic dielectric scatterers in a homogeneous dielectric matrix. A PBG material affects the properties of traveling electromagnetic waves in much the same way that a crystal of atoms affects the properties of electron waves. Consequently, photons in PBG materials can have band structures, gaps, localized defect modes, and surface modes. By allowing the trapping, localization, and channeling of light with very low loss, these new materials have the potential of completely revolutionizing the basic elements of photonic and optoelectronic integrated circuits. The bending radius of a conventional planar waveguide is limited to 1 cm by scattering losses; this geometry is incompatible with integrated photon distribution on a chip. A PBG material will allow a 10 um radius bend, and provide a gateway to microphotonics. The research addresses a broad range of fundamental issues in novel synthesis pathways for inhomogeneous microstructures, new photonic phenomena, and components for well-defined systems applications. The group has already fabricated and begun to characterize a one-dimensional PBG waveguide with a bandgap centered at 5 um, composed of a set of colinear air holes in Si. Similar structures in GaAs are being tested.
Participating faculty and departmental affiliations: Professors H. A. Haus, E. P. Ippen, L. A. Kolodziejski, and L. R. Reif (Electrical Engineering and Computer Science); E. R. Brown (Lincoln Laboratory); L. C. Kimerling (Materials Science and Engineering); and J. D. Joannopoulos (Physics).
The objective of this group is to develop the chemistry and molecular-level processing needed to control and manipulate the molecular and supermolecular organizations of macromolecular systems with novel electrical and optical properties. The development and utilization of combined molecular/supermolecular engineering schemes will make it possible to design and fabricate complex, multiphase or multicomponent systems with controllable molecular architectures and well-defined morphological arrangements. Thus, it will be possible to create multi-component systems in which each component serves a well-defined function and is molecularly positioned to achieve a specific and tunable electrical, optical, or chemical response. The juxtaposition of different components, such as semiconductor nanocrystallites and conjugated polymers, may result in new and useful electronic and optical behavior. Applications of interest include highly anisotropic electrically conducting films, photonic devices, periodic dielectrics, and thin film electroluminescent and energy storage devices. This group has recently discovered a new way of making light-emitting polymer films and super-paramagnetic films that may be useful in security applications.
Participating faculty and departmental affiliations: Professors R. E. Cohen (Chemical Engineering); M. Bawendi, R. R. Schrock, and R. J. Silbey (Chemistry); and M. F. Rubner and E. L. Thomas (Materials Science and Engineering).
Cooperative behavior in the presence of frozen-in randomness, i.e. ordering in the presence of quenched disorder, permeates all of materials science. Whereas phase changes in perfect systems are well-understood, the disorder challenges our ability to understand even qualitative effects and to make precise predictions and measurements. Cooperative phenomena in the presence of quenched randomness may also underlie fundamental mechanisms of life sciences and have applications to information sciences in, for example, neural networks or coding-decoding processes. The chief focus of this group is the study of gels with random distributions of positive and negative charges. The gel work recently received the Discover Magazine Technology Award and the R&D Magazine R&D 100 Award.
Participating faculty and departmental affiliations: Professors C. W. Garland (Chemistry); and A. N Berker, R. J. Birgeneau, M. Kardar, J. D. Litster, and T. Tanaka (Physics).
The properties of polycrystalline materials are largely dominated by the properties of their surfaces and grain boundaries. Oxides possess the greatest range of interfacial properties of scientific and technological interest, owing to a richness of chemical and electronic phenomena not found in most other materials. However, due to greater complexity, these materials are at the same time the least understood. The goal of this IRG is to develop a unified and comprehensive understanding of the role of atomic level structure, chemistry, and local electronic structure in determining the physical properties of crystal interfaces. Towards this goal, a collaborative effort in the growth, detailed characterization, and computational modeling of grain boundaries in model oxides is proposed. The two materials chosen for study, TiO2 and ZnO, have technological applications that depend on the behavior of their interfaces: TiO2 is the primary opacifying component in paint and ZnO is the material of which varistors are made. The successful growth of single grain boundaries in these oxides and the use of electron microscopy to study their chemistry on the nm length scale has enabled this group to approach this problem in a way never before possible. This group has recently demonstrated a correlation between the chemistry and electrical properties of interfaces in ZnO varistor material.
Participating faculty and research staff and departmental affiliations: Professors R. W. Balluffi, Y.-M. Chiang, H. L. Tuller, J. B. Vander Sande, and B. J. Wuensch (Materials Science and Engineering); and Dr. A. J. Garratt-Reed (CMSE).
The discovery of high-temperature superconductivity in copper oxides has renewed interest in the more general problem of transition metal oxides, where strong correlations between the electrons are known to play a key role. For example, the parent compound La2CuO4 is an antiferromagnetic insulator, contrary to the prediction of band theory, and becomes metallic and superconducting when doped. Many believe that the superconductivity is a new manifestation of the correlated behavior of the electrons in the two-dimensional copper oxide layers. It follows that the physics of strong correlations must be better understood before the superconductivity can be explained. The goal of this group is, therefore, to study the properties of transition metal oxides in order to guide the development of a theory of correlated systems and ultimately explain the mechanism of high-Tc superconductivity. The group's strategy for reaching its goal has three parts: detailed studies of the magnetic, electronic, and optical properties of single crystals, development of a theoretical framework for the analysis of the data, and a search for new compounds. The growth of large single crystals for neutron scattering experiments is a unique strength of this effort. Using these crystals the group recently discovered the spatial ordering of oxygen used to dope La2CuO4.
Participating faculty and departmental affiliations: Professors R. J. Birgeneau, M. A. Kastner, and P. A. Lee (Physics); and H.-C. zur Loye (Chemistry).
The research focuses on identifying the mechanistic connections between structure, morphology, and macroscopic properties of polymers. The project aims at establishing the fundamental connections between polymer microstructure and mechanical performance, and the design of new forms of heterogeneous polymer systems.
Participating faculty and departmental affiliations: A. S. Argon, M. C. Boyce, and D. M. Parks (Mechanical Engineering); G. C. Rutledge and R. E. Cohen (Chemical Engineering).
This program seeks to couple current techniques in ab-initio electronic structure calculations with Monte-Carlo based simulations in order to relate quantitatively the microscopic information on local bonding and chemistry to the kinetics of defect mobility and microstructural evolution. First-principles quantum mechanical methods and atomistic and mesoscopic simulations will be applied to develop a quantitative description of dislocation nucleation and mobility on epitaxial semiconductor films in order to provide a sound modeling tool.
Participating faculty and research staff and departmental affiliations: T. A. Arias (Physics); Dr. V. Bulatov (Mechanical Engineering); and S. Yip (Nuclear Engineering).
This initiative exploits new capabilities for processing of mesoscopic systems, including self-assembled arrays of semiconductor quantum dots and the fabrication of mesoscopic structures in Ge/Si. The group will study electronic transport in these systems to better understand the fundamental physics of these systems. In addition, the effects of GHz to THz radiation on the conductance of mesoscopic structures will be studied with an eye to possible applications.
Participating faculty and departmental affiliations: R. Ashoori, M. A. Kastner, P. Lee, L. Levitov, X.-G. Wen (Physics); M. G. Bawendi (Chemistry); E. A. Fitzgerald (Materials Science and Engineering); and Q. Hu (Electrical Engineering and Computer Science).
Progress has been made in developing new methods of calculating physical and chemical properties of materials from first principles. These are being applied to corrosion of Cr and dislocation motion in Si. T. A. Arias (Physics).
Calculations are underway to predict the structure and defect chemistry of grain boundaries in ZnO. Predictions of boundary structures and analysis of the thermodynamics of de-segregation of Bi from grain boundaries are being tested by members of IRG-IV. G. Ceder (Materials Science and Engineering).
Recently developed high resolution scattering techniques are used to characterize both the dynamics of spin diffusion and local ordering in condensed phases. It is planned to quantify both the short and long time behavior of spin diffusion in well characterized systems, and to apply these new methods to studies of structural and phase behavior in the presence of quenched disorder. D. G. Cory (Nuclear Engineering).
Centrifugal techniques are used to determine the residual saturation of trapped non-wetting phase following a wetting displacement as a function of pore geometry. The data are used to construct phase diagrams. P. J. Culligan-Hensley (Civil and Environmental Engineering).
Block copolymers with an amorphous block and a ferroelectric liquid crystalline block are being synthesized. Such materials may have useful electro-optical or mechano-optical properties. P. T. Hammond (Chemical Engineering).
Phase transitions in gels discovered by Tanaka and studied intensively by IRG-III, may be useful as synthetic muscles, servomechanisms, and sensors. Gels containing ferrofluids are being synthesized that are sensitive to magnetic fields and gels that are sensitive to specific contaminants in water. S. B. Leeb (Electrical Engineering and Computer Science).
This project is working to establish and demonstrate the guiding principles for the design and synthesis of polymers capable of molecular recognition and enzymatic activity. The research will develop an understanding of the principles that govern the macroscopic phase behavior of gels in terms of molecule-mediated attraction between polymers. S. Masamune (Chemistry).
For thin film organic heterostructures, of the kind fabricated by IRG-II, layering, perfection and interfacial structure are important to device performance. X-ray and neutron reflectometry is used to characterize roughness as a function of the number of polymers layers. A. M. Mayes (Materials Science and Engineering).
CMSE's programs contribute to the education of both undergraduate and graduate students in a variety of ways. A joint program with the Materials Processing Center (MPC) brings students from all across the nation to MIT in the summer to become involved in materials research. The SEFs are also important in undergraduate education. Courses, such as those in X-ray scattering and microfabrication, teach the students to use processing and characterization facilities and to carry out research projects using the equipment. A course entitled Materials Synthesis and Processing, taught by the Department of Materials Science and Engineering and initiated with partial NSF support, uses the SEFs extensively. In addition, short courses are taught using the facilities during the Independent Activities Period. At the graduate level, CMSE plays a critical role in the education of almost all the students at MIT who do materials-related research. In addition to those involved in the IRGs, the shared facilities are used by graduate students from 11 academic departments.
CMSE collaborates with other laboratories and centers at MIT that carry out materials-related research and engineering with direct involvement of industry and other sectors and CMSE facilities are modified in coordination with these organizations to assure that the overall spectrum of facilities offered by MIT is as broad as possible without unnecessary redundancy.
The SEFs are a critical feature of CMSE's collaborations with non-MIT personnel. The facilities are made available to any researcher from a nonprofit institution and to industrial researchers when equivalent facilities are not available commercially. During the past year, CMSE facilities have been utilized by 26 commercial organizations and 11 outside academic institutions. The current CMSE/IBM X-ray participating research team (PRT) at the National Synchrotron Light Source (NSLS) at Brookhaven, the CMSE/IBM/McGill PRT under construction at the Argonne Advanced Photon Source (APS), and the Brookhaven/CMSE/AT&T/Exxon neutron scattering PRT at the Brookhaven High Flux Beam Reactor are very special facilities constructed and operated with direct industrial and government laboratory collaboration. These PRTs and the neutron diffraction PRT at the National Institute of Standards and Technology (NIST) provide time for use of facilities to users from all sectors. Finally, several of the IRGs participate in direct research collaboration with industry and other sectors. This is important for exchange of knowledge and the education of graduate students, for it provides them with direct experience of industrial research.
Two male members were added to the staff during the past year: Dr. Fang Cheng Chou, Research Associate, and Dr. David C. Bell, Postdoctoral Associate, who were both appointed in January, 1996. Departures from the Center's staff over the past year include research staff members Dr. Neil Rowlands, who resigned in March 1996, and René Holaday, who resigned in August, 1995.
Of the 13 students participating in the CMSE Undergraduate Research Opportunities Program, funded by the National Science Foundation as part of the MRSEC Program, eight were women and five were men. Again this summer, CMSE is collaborating with the MPC in sponsoring a joint ten-week summer internship program. Nine interns were selected from applications submitted by over 100 undergraduates from both MIT and other universities from around the country. Four of these scholars are women. The interns include Blake M. Ashby (Utah State University), Anna Domnich (Columbia University), Jay B. Ewing (Reed College), Thomas J. Fennimore (Swarthmore College), Mahesh K. Mahanthappa (University of Colorado), Andrea R. Palmisano (Tulane University), Rachel A. Soltis (Bryn Mawr), Joshua S. Weitz (Princeton University), and Melody T. Yung (MIT).
As part of its outreach program, CMSE participates in the cooperative employment in its shared experimental facilities of students from Northeastern University and Wentworth Institute. Of the six students employed this year, one was a woman and three were African-American men. Peter Bennett, Jeol Holmes, Suzanne Nicol, Sleamms Petit-Maitre, Costas Pitsillides, and Andrew Williamson worked as co-op students in two of the Center's SEFs over the course of the past year.
CMSE also participates in the Cambridge Teenwork program that fosters after school and summer office employment of Cambridge high school students. An African-American young woman, Shani Colleymore, who formerly participated in the science and engineering day camp, worked for the entire school year.
The Center continued its very successful science and engineering summer day camp for seventh- and eighth-grade students from a local public school who are members of underrepresented minority groups, including nine African-Americans and three Hispanic-Americans, of which four were male and eight were female. The students were supervised by volunteer faculty and staff, as well as four MIT students, including one African-American woman, and one Hispanic man. These students were Jaime Amaya, Sharonda Bridgeforth, Merideth Rising, and Peter Tsang.
We continued the CMSE graduate minority research assistant (RA) program to fill the need for support for minority students in their last two years of graduate study. During the 1995-96 academic year, the Center provided RA support to an African-American woman in the Department of Physics and an Hispanic male in the Department of Chemistry. In addition, seed funding was granted to one female faculty member working in the field of materials science and engineering who is a member of an under-represented minority group.
Marc A. Kastner
MIT Reports to the President 1995-96