CENTER FOR MATERIALS SCIENCE AND ENGINEERING

In September of 1994, the Center for Materials Science and Engineering (CMSE) at MIT was awarded one of the first National Science Foundation Grants under the new Materials Research Science and Engineering Center (MRSEC) program. After a second competition in 1996, the MRSEC grant at MIT remains the largest of the 24 at universities throughout the nation. We describe below the mission of CMSE and the methods used to reach its goals.

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. Much of the research addresses intermediate-term engineering problems, often with the participation and support of industry. However, the longer-range problems, especially those that require a multi-investigator approach, are often overlooked. In this environment CMSE has a special mission: to encourage research and education in the fundamental science of materials and in the engineering of materials for long range applications that will meet the needs of society. CMSE promotes collaboration among MIT faculty and 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) 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. 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.

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 has begun to prepare for the next MRSEC competition, beginning in September, 1997. An internal competition has been held to determine what IRG's will be proposed. Of the nine candidate groups, five will be chosen for inclusion in the new proposal. Several new groups, initially supported with seed funds, have emerged as outstanding candidates.

INTERDISCIPLINARY RESEARCH GROUPS

Microphotonic Materials and Structures
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 in homogeneous microstructures, new photonic phenomena, and components for well-defined systems applications. The group has recently fabricated and characterized a one-dimensional PBG material consisting of a set of collinear air holes in Si By omitting one of the lasers.

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).

Molecular and Supermolecular Engineering of polymeric Systems with Novel Electronic and Optical Properties
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 A. Mayes, M. F. Rubner, and E. L. Thomas (Materials Science and Engineering).

Phase Behavior in the Presence of Quenched Randomness and Frustration
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.

Participating faculty and departmental affiliations: Professors C. W. Garland (Chemistry); and A. N. Berker, R. J. Birgeneau, M. Kardar, and T. Tanaka (Physics).

Structure, Chemistry, and Transport Properties of Intercrystalline Interfaces
The properties of polycrystalline materials are largely dominated by their surfaces and grain boundaries. For example, TiO₂ is the primary component in paint that makes it opaque, and the yellowing of paint in the presence of sunlight is an example of an interface effect that costs society great sums. However, these same photochemical reactions make TiO₂ useful for degradation of sewage. 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. This group has recently demonstrated a correlation between the chemistry and electrical properties of interfaces in ZnO varistor material.

Participating faculty and departmental affiliations: Professors G. Ceder, Y.-M. Chiang, H. L. Tuller, and J. B. Vander Sande (Materials Science and Engineering); and J. Ying (Chemical Engineering).

Transition Metal Oxides
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, T. Imai, and P. A. Lee (Physics).

INITIATIVES

Microstructure and Mechanical Performance of Polymeric Materials
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. This group has made a breakthrough in the toughening of polyethylene.

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).

Multiscale Materials Modeling from the Electronic Structure-Atomistic Levels
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).

Electronic Transport in Mesoscopic Systems
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).

SEED PROJECTS

During the past year CMSE has supported the following seed projects:

• Ab Initio Study of the Properties of Materials on the Nanoscale, T.A. Arias (Physics)

  
  

• Investigations of Spin Diffusion and Local Ordering by High Resolution Scattering, D. G. Cory (Nuclear Engineering)

  
  

• Investigation into Nonwetting Phase Entrapment During Fluid Transport in Porous Media, P. J. Culligan-Hensley (Civil and Environmental Engineering)

  
  

• Design and Synthesis of Thermoplastic Elastomers with Side Chain Liquid Crystalline Soft Segments, P. T. Hammond (Chemical Engineering)

  
  

• Polymer Gel Actuators and Sensors, S. B. Leeb (Electrical Engineering and Computer Science)

  
  

• Gels for Molecular Recognition, Accumulation, and Release, S. Masamune (Chemistry)

  
  

• Conductive Ladder Polymers: Pre-Assembly in the Synthesis of Complex Supramolecular Materials, T. M. Swager (Chemistry)

CMSE's programs contribute to the education of both undergraduate and graduate students in a variety of ways. The CMSE colloquium series has provided an opportunity for graduate students from many departments to learn about the broad range of research activities at MIT. 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 electron microscopy, 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.

COLLABORATION WITH INDUSTRY AND OTHER SECTORS

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. A new grant from the DoE has made possible the purchase of magnets to carry out neutron and x-ray measurements at fields that had been previously inaccessible. 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.

AFFIRMATIVE ACTION

CMSE is committed to providing opportunities to women and minorities through hiring and educational and research programs. During the past year, we hired one African-American woman, and promoted one woman and three men. Debra Henry was appointed to the support staff in July 1996. Departures from the Center's staff over the past year include research staff members Virginia Esau, Administrative Officer for the past nine years who transferred to the Physics Department as Administrative Officer in May 1997; and Richard Perilli, who resigned in July 1996.

Of the seventeen students participating in the CMSE Undergraduate Research Opportunities Program, funded by the National Science Foundation as part of the MRSEC Program, six were women and eleven were men. For the fourth summer, CMSE is collaborating with the MPC in sponsoring a joint ten-week summer internship program. Eight interns were selected from applications submitted by over 100 undergraduates from both MIT and other universities from around the country. Two of these scholars are women and one is an African-American. The interns include Bababunmi Adekore (North Carolina State University), Ian Appelbaum (Rensselear Polytechnic Institute), Jennifer Craft (Mississippi State University), Jenny Cutler (Brigham Young University), Jeffrey Gore (MIT), Christopher Leitz (Pennsylvania State University), Andrew Read (University of Illinois), and Miroslav Shverdinovsky (Cornell University).

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. Three students were employed this year. One is a woman and two are men. One of the students is African-American. Suzanne Nicol, Nikolay Pokrovskiy, and Patrick Boisvert have worked as co-op students in two of the Center's SEFs over the course of the past 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. This year's students included six African-Americans and four Hispanic-Americans, of which seven were male and three were female. The students were supervised by volunteer faculty and staff, as well as four MIT undergraduates, including one of Hispanic ethnic origin. These students were Julieann Villa, Melody Kuroda, Farzana Mohamed, and Elaine Haberer.

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 1996-97 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.

More information about the Center for Materials Science and Engineering can be found on the World Wide Web at the following URL: http://web.mit.edu/cmse/www/

Marc A. Kastner

MIT Reports to the President 1996-97