Combinatorial Approach to Materials

Throughout the history of mankind, scientists and engineers have relied on the slow and serendipitous trial and error process for materials discovery. This process allows only a small number of materials to be examined in a given period of time. The combinatorial approach provides a means to quickly investigate a large number of previously unexplored compositions. High-throughput synthesis and characterization techniques are implemented to carry out highly integrated search-and-discovery processes. Within the last two decades, combinatorial chemistry and screening for new drugs and biomolecules have already revolutionized the pharmaceutical and DNA-sequencing industries. Its application to inorganic solid-state materials was pioneered at Lawrence Berkeley National Laboratory in the 1990s. The combinatorial methodology is now being implemented in a wide range of materials applications around the world.

In many applications, timely identification and/or availability of a material with specific functionality will make or break the development of future technology. The general trend in materials discoveries is that new materials tend to have increasingly complicated structures, often consisting of a large number of elements. This is clearly illustrated in the case of high-temperature superconductors, where the highest superconducting transition temperature is currently observed in the HgBa2Ca2Cu3O8+d compound with a complicated layered structure. The combinatorial techniques can be used to address materials issues at different levels in a wide range of topics ranging from semiconductor manufacturing and thin-film smart materials to catalytic powders and biomaterials. It is widely anticipated that combinatorial approach to materials will lead to accelerated innovation in various industries broadly benefiting our society.

The application of the combinatorial approach to technologically relevant electronic materials is best implemented in the form of thin-film libraries. Combinatorial thin-film libraries encompassing large compositional variations can be generated using different thin-film deposition techniques. We have developed several newly designed combinatorial deposition chambers at the University of Maryland including (1) versatile pulsed-laser deposition systems with modular combinatorial flanges and (2) multi-gun ultra-high vacuum sputtering systems. There is also a 12-pocket dual electron beam combinatorial deposition system located at NIST which was developed in collaboration with Dan Josell and Leo Bendersky. As a complementary technique to fabricating discrete combinatorial libraries (Figure 1), it has been demonstrated that for select materials systems, entire ternary and/or binary phase-diagrams can be created on individual chips. This continuous phase-spread technique has proven to be a powerful means to map out unexplored regions of materials phase-space (Figure 2).

Often the biggest challenge in the combinatorial approach is to come up with an effective tool for rapid characterization. Parallel detection schemes and non-destructive scanning probe microscopes are implemented to facilitate high-throughput screening of the combinatorial samples in order to identify compositional regions with enhanced physical properties. There are a number of recently invented scanning probe microscopes available at the University of Maryland that are ideal for scanning the libraries. These include the scanning superconducting quantum interference device (SQUID) microscope and scanning microwave microscopes. Our current projects include investigation of novel magnetic shape memory alloys (supported by Office of Naval Research), nanocomposite permanent magnets (supported by DARPA) and functional metal oxide materials (supported by NSF).

For detailed research activities on combinatorial materials research program at the University of Maryland , go to http://www.isr.umd.edu/CoSMIC/

Selected Recent Publications

[1] Hideomi Koinuma and Ichiro Takeuchi, “Combinatorial Solid State Chemistry of Inorganic Materials,” Nature Materials 3, 429 (2004).

[2] K.-S. Chang, M. A. Aronova, C.-L. Lin, M. Murakami, M.-H. Yu, J. Hattrick-Simpers, O. O. Famodu, S. Y. Lee, R. Ramesh, M. Wuttig, I. Takeuchi, C. Gao, L. Bendersky, “Exploration of Artificial Multiferroic Thin Film Heterostructures Using Composition Spreads,” Applied Physics Letters, 84, 3091 (2004) .

[3] Chen Gao, Bo Hu, Pu Zhang, Mengming Huang, Wenhan Liu, and I. Takeuchi, “Quantitative Microwave Evanescent Microscopy of Dielectric Thin Films Using a Recursive Image Charge Approach,” Applied Physics Letters, 84, 4647 (2004).

[4] Combinatorial Materials Syntheses , edited by Ichiro Takeuchi and Xiao-Dong Xiang, publisher: Marcel Dekker, 2003 (ISBN:0-8247-4119-6)

[5] I. Takeuchi, W. Yang, K.-S. Chang, M. Aronova, R. D. Vispute, T. Venkatesan, L. A. Bendersky, “Monolithic Multi-channel UV detector Arrays and Continuous Phase Evolution in Mg x Zn 1-x O Composition Spreads,” Journal of Applied Physics 94, 7336 (2003).

[6] Y. Matsumoto, H. Koinuma, T. Hasegawa, I. Takeuchi, F. Tsui, and Young K. Yoo, “Combinatorial Investigation of Spintronic Materials,” MRS Bulletin 28, 734 (2003).

[7] I. Takeuchi, O. Famodu, J. C. Read, M. Aronova, K.-S. Chang, C. Craciunescu, S. E. Lofland, M. Wuttig, F. C. Wellstood, L. Knouse, A. Orozco, “Identification of Novel Compositions of Ferromagnetic Shape Memory Alloys using Composition Spreads,” Nature Materials 2, 180 (2003).

[8] M. A. Aronova, K. S. Chang, I. Takeuchi, H. Jabs, D. Westerheim, A. Gonzalez-Martin, J. Kim, B. Lewis, “Combinatorial Libraries of Semiconductor Gas Sensors as Inorganic Electronic Noses,” Applied Physics Letters 83, 1225 (2003).

[9] Ichiro Takeuchi, Robert Bruce van Dover, and Hideomi Koinuma, “Combinatorial Synthesis and Evaluation of Functional Inorganic Materials using Thin-Film Techniques,” MRS Bulletin 27, 301 (2002).

[10] K. S. Chang, M. Aronova, O. Famodu, I. Takeuchi , S. E. Lofland, J. Hattrick-Simpers, H. Chang, “Multimode Quantitative Microwave Microscopy of In-situ Grown Epitaxial Ba 1-x Sr x TiO 3 Composition Spreads,” Applied Physics Letters 79, 4411 (2001).

Figure 1. Photograph of an electronic nose: a semiconductor gas sensor library. From reference [8]

Figure 2. Photograph of a micromachined cantilever library for detection of shape memory alloys. Ni-Mn-Ga composition spread is deposited on this library. From reference [7].

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