Kenneth R. Poeppelmeier, Ph.D. - US grants

It is proposed that the PI be Kenneth Poeppelmeier (Northwestern) and an executive committee consisting of J. M. Honig (Purdue), Jeremy Burdett (Chicago), Robert McCarley (Iowa State) have the major responsibility of administering the grant. The funds from this grant would be made available to cover travel and living expenses of student and faculty participants during the entire period of the program, and travel and subsistence for scientists chosen as lecturers during the first week of the program. Funds also would provide for travel of all student and faculty participants to return to Northwestern at the end of the summer period, when each participant can present a report on the results of his or her project in a symposium format. This symposium would be held over two day period, and would be vital in furthering the participant's overview of the program, their ability to organize and report research results, and to impart a professional orientation to further work in the field of solid state chemistry.

Reactions of one solid with another that occur at room temperature are not common in solid state chemistry. The reaction of metal hydroxides with salts is a particularly unusual example. This reaction they have called salt imbibition and it provides a new synthetic method for the preparation of high surface area (HSA) mixed metal oxides. Such compound precursors can be decomposed to give mixed oxides. Because all reactions can be carried out at low temperature, the products will not sinter and will retain their porous character and relatively high surface area. Compared to commercially available HSA oxides (e.g. aluminas, silicas and zeolites) mixed metal oxides offer an entirely new range of materials for applications in ceramics, catalysis and emerging materials science applications. Because HSA mixed oxides have not been widely available their surface chemistry is unknown. Ion-exchange, a diffusion dependent reaction, occurs not only near the surace but can be an important reaction in the interior of a mixed metal oxide crystallite. A related intrinsic characteristic of a HSA oxide is its solid-acid chemistry. To distinguish the type of surface chemistry that can be expected from these novel materials well known reactions such as the isomerization of 3,3-dimethylbutene to 2,3- dimethylbutenes, 2- and 3-methylpentenes, and n-hexenes will be investigated.

Cohen 9304725 Northwestern University, E.I. Du Pont de Nemours and Dow Chemical have formed a Collaborative Access Team, known as DUNU, and are proposing to instrument and operate a sector at the Advanced Photon Source. A funding schedule, with costs to be shared equally by both parties has been agreed upon, covering both a five year construction phase, as well as a ten year minimum operations phase. Currently DUNU employs three full-time senior scientists and engineers headquartered at Northwestern (a nationwide search is on for a fourth senior scientist), with extensive experience in beam line construction and operations both at the Cornell High Energy Synchrotron Source (CHESS) and the National Synchrotron Light Source (NSLS Brookhaven), plus management of one of the largest x-ray diffraction laboratories in the country. The purpose of this Collaborative Access Team is to carry out research on the structure of advanced materials. Our understanding of the structure (atomic to micron level) is a crucial prerequisite to the development of new materials with enhanced properties. Synchrotron radiation has become an essential tool in every aspect of structural analysis and has revolutionized many subfields of science and engineering. Many members of our CAT have been very active users of our national facilities. The vastly increased capabilities of "third generation" machines, such as the APS and similar storage rings in Europe and Japan, promise a second revolution. A broad research program has been formulated, involving currently more than 30 principal investigators from Du Pont and Northwestern. At least fifty other scientists and engineers, students and post-doctoral fellows will ultimately be involved. Although many fields of materials science and engineering are represented in this research program, the research to be supported by the instrumentation in this project has a particular focus: It deals with materials, whose intermediate scale structure (nanometer to micrometer) has a profound influence on their properties. Such materials are of immense technological importance and include precipitation-hardening alloys, ceramics, polymers, cement and composite materials. Many elements of this research program are totally beyond current capabilities at available x-ray sources (conventional and synchrotron). The instrumentation that we will develop depends heavily (or crucially) on the characteristics of the APS. It is grouped in two experimental stations, both utilizing undulator radiation: 1. General purpose scattering instrument, suitable for all types of diffraction experiments (amorphous, powder and single crystal work, surface and interface diffraction, standing waves etc.). Collimated beams (0.1-1 mm) and microbeams will be available for diffraction and microprobe work. The microbeam capability is of particular interest in the context of this proposal. 2. Small Angle X-ray Scattering microtomography instrument equipped with 2-D position sensitive detector and environmental chamber with multiple attachments (low and high temperature, UHV, sample changer). This may be the first x-ray instrument with sufficient imaging and scattering resolution to allow the two techniques to overlap in studying micron- sized structural features. We believe that DUNU possesses all the key ingredients of a productive and strong Collaborative Access Team. Northwestern University anchors an interactive research community through its interdisciplinary research centers (many of which, such as the Materials Research Center and the Center for Advanced CementBased Materials are supported by the National Science Foundation) and individual faculty research. E.I. Du Pont de Nemours & Co. brings its immense capabilities in scientific research and development. It is a world leader in process chemistry and engineering and t he manufacturing of high technology products. It is the intent of this collaboration not only to share a station at this major facility, but to develop interactive, collaborative research between the two institutions (we have installed a videoconferencing link to aid this interaction).

9412971 Poeppelmeier The primary focus of this research is to develop the concept of salt imbibition for the purpose of generating new synthetic methods and chemical reactions that lead to novel precursors for high surface area mixed metal oxides that are catalytically active. An emphasis will be on transforming the precursors at low temperatures to mixed metal oxides, characterizing the solid-state products, and studying the nature of acidic and basic sites at the surface and their role on surface reactivity. %%% The synthesis and characterization of new materials is one of the major forces in science that causes change and leads to advances in technology. Solid-state chemical approaches to generating novel catalytic materials such as the high surface area metal oxides that are the subject of this research are offering new applications in emerging areas of heterogeneous catalysis.

9727516 Poeppelmeier The preparation of new materials is one of the most challenging problems in modern solid-state chemistry. The research objective over the period of the next three years is to synthesize a large number of mixed metal oxyfluorides prepared from (hydrogen fluoride) x pyridine/pyridine/water solution (150 degrees centigrade, autoclave autogenous pressure) using metal oxides as reagents. The "composition space" approach will establish individual regions of stability (crystallization fields) and enable the selective crystallization of different phases within each system studied. Structures are expected which range from polynuclear clusters to one dimensional chains, two-dimensional layers and three dimensional frameworks. The hydrolytic chemistry of multi-cation precursors, templating methodology, and pH controlled oxolation (polyanions) and olation (polycations) reaction chemistry under study will advance our understanding of inorganic chemistry. %%% The design of inorganic solids is the important step in the development of materials that enhance our living standards. Research is proposed to develop new methodologies for inorganic chemistry leading to more complex inorganic solids compared to those that are presently available for use in computers, automobiles and as catalysts in the chemical and petroleum industry. ***

Technical Summary
Technologies that require high-performance nonlinear optical (NLO) materials with enhanced optical properties at the microscopic and macroscopic level depend on inorganic materials that exhibit large optical nonlinearities (possessing a dipole). The rational design of crystal structures, in particular noncentrosymmetric materials, and how to differentiate polar, polar-chiral, and chiral structures, is an ongoing theme in crystal engineering. These materials are essential for the modification of the amplitude, phase, or frequency of an optical signal. Polar distortions in metal centered octahedra are the origin of the nonlinear optical response in metal oxides. Octahedrally coordinated transition metal cations in groups 4,5,6 are unstable in mixed metal oxides with respect to intraoctahedral distortions, which can be understood through the second order Jahn-Teller theorem. This program explores research on noncentrosymmetric structures based on acentric transition metal oxyfluorides. These materials will provide a large and new class of solids with properties associated with piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG), all properties associated with noncentrosymmetric space groups. This work is supported by a grant from the Solid State and Materials Chemistry Program in the Division of Materials Research.

Non-technical Summary
The rational design of structures based on the chemical nature of molecular components, a longstanding and exciting research topic in organic solid-state chemistry, is an emerging theme of crystal engineering. Technologies that require high-performance nonlinear optical (NLO) materials with enhanced optical properties, however, depend on inorganic materials that exhibit large optical nonlinearities. Structures lacking inversion symmetry are a requirement for important current and future technologies that have been created by numerous inventions during the past two decades. These materials provide a large and new class of solids for studies in basic science associated with the noncentrosymmetric space groups. We propose an exploratory research program on these materials, which were highlighted recently in an article entitled "China's Crystal Cache" (Nature 2009, 457, 953-955). In this Nature article the critical national need for synthesis-based efforts to discover and to grow suitable crystals of these new materials was emphasized. This work is supported by a grant from the Solid State and Materials Chemistry Program in the Division of Materials Research at the National Science Foundation (DMR-1005827).

Non-technical abstract

Solid State Chemistry continues to undergo dramatic growth and increasingly active involvement in emerging interdisciplinary research areas. This is due to many factors. These include the widespread appreciation of the importance of new materials in many areas of basic science and technology, the recent opening of the nanometer length scale for chemical reaction and molecular manipulation, the realization that complex molecular systems can be designed to display properties with characteristics unique or complimentary to those in the traditional solid state, and many other factors as well. The field has been continuously open to the accommodation of new ideas and directions as they develop. As a consequence of this continuing growth and redefinition, it is important for to us to periodically consider our current directions and future goals as a community. In response to this need, the goal for this workshop titled Third NSF Workshop: The Status of Solid State Chemistry and its Impact in the Physical Sciences is to assess the current state of solid state chemistry and explore its impact on neighboring disciplines and industry. This workshop follows the first workshop held in 1998 on The Present Status and Future Directions of Solid State Chemistry and Materials and focused discussion on the core of our discipline. Continuing developments of the field, especially in nanoscale science and a variety of highly interdisciplinary areas, became the topic of a second workshop held in 2001 at UC-Davis on Future Directions in Solid State Chemistry. The results of our discussions will be disseminated to the community as a whole through publication in a materials chemistry journal and on the internet.

Technical abstract

The goal of the third NSF workshop on The Status of Solid State Chemistry and its Impact in the Physical Sciences is to assess the current state of solid state chemistry and explore its impact on neighboring disciplines in the physical sciences and industry. We plan to articulate the solid state chemistry communitiess sense of the opportunities and directions it wishes to take in the future, and to seek insights into how students ought to best be trained. The findings of the workshop could act as a vehicle for informing the solid state chemistry community of programs and opportunities for support at NSF and elsewhere. The workshop will produce a report that will be available to the scientific community and the funding agencies, in particular to NSF. In contrast to the two workshops that have preceded the proposed one in 1998 and 2001, and focused respectively on the core of our discipline and the interfaces of solid state chemistry with other disciplines in both the biological and physical sciences, the focus of the proposed workshop will be two-faceted: (i) we will seek a close look at the discipline of solid state chemistry in the beginning of the third millennium and (ii) we will explore its continued impact and relationship to neighboring disciplines in the physical sciences and also industry. Topics to be discussed include accomplishments, emerging research directions and underdeveloped areas. Furthermore, an assessment of how solid-state chemistry is impacting the physical sciences, through continuing advances and the many ways of interacting across disciplinary boundaries, would help the NSF and the scientific community better appreciate its value and contributions in the greater scientific and societal context. Important community input for the workshop will also include the discussion of existing and new modes for educating students, and the development and use of national facilities for performing state-of-the-art research in our field.

TECHNICAL SUMMARY

Emerging technologies require high-performance nonlinear optical (NLO) materials that exhibit enhanced optical properties at the microscopic and macroscopic level. The rational design of crystal structures, in particular noncentrosymmetric (NCS) materials, and how to target polar, polar-chiral, and chiral structures, is an ongoing theme in crystal engineering. A new class of potentially high performance NLO inorganic materials, solid-state oxide-fluorides, has been identified with the synthesis of new compounds containing [MOxF6-x]2- units in inorganic, solid-state environments. In the process it has been discovered that i) the use of fluoride ligands with early-transition metals (ETMs) enhances the second-order Jahn-Teller distortion in comparison to pure oxide ETM compounds, ii) the synthesis of NCS materials can be achieved with the use of polar basic-building units (BBUs), iii) design of NCS BBUs can predictably lead to NCS structures, iv) the synthesis of compounds that contain two, separate anionic BBUs is likely to result in an NCS compound, and v) the synthesis of ETM oxide-fluoride compounds can produce energy-storage materials such as high-potential primary batteries. Drawing from these learned principles, a program of discovery-based research on NCS structures based on acentric ETM oxide-fluorides (ETMOFs) is planned. These materials comprise a large and new class of solids with properties associated with piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG). The structural-property relationships that give rise to high, low, or null nonlinearities of the NLO material are examined. Finally, the growth of large crystals (on the order of 1 cm3) allows detailed analysis with measurements of the NLO tensor and phase-matchability properties, and other properties of interest such as piezoelectricity. The materials synthesized will have potential use in relaxor ferroelectrics and non-linear optics. These materials will have a high damage threshold and the potential for bulk growth to create large, single crystals suitable for optical use and examination. This work is supported by the Solid State and Materials Chemistry Program.

NON TECHNICAL SUMMARY
As recently described in a Nature News Feature, the highly-efficient non-linear optical (NLO) oxide-fluoride material KBe2BO3F4 and other NLO materials are essential to act as wave guides for the modification of the amplitude, phase, and/or frequency of an optical signal. Such materials are used in femtosecond laser spectroscopy and-more recently-to generate UV laser light for nanolithography. Such NLO materials are increasingly needed to upconvert laser light to higher energies by second-harmonic generation (SHG). Current research and engineering activities in the field of NLO materials typically concern synthesis of NLO crystals; however, research is lacking in understanding how to design NLO materials and why materials exhibit a particular NLO response. While exploring the fundamental driving factors that create NLO materials, research will be performed to grow large (on the order of cm3) single crystals with a floating zone image furnace to allow a quantitative understanding of the interaction of light with the NLO material. This project concerns such analyses and progress made towards rational synthesis of solid-state inorganic materials and analysis of their structure-property relationships. These analyses of basic principles of the chemistry by graduate students and postdoctoral associates - who are engaged in local education, teaching, mentoring, and leadership - will facilitate broad understanding of stable solid-state compounds.

This award is supported by the Major Research Instrumentation and the Chemistry Instrumentation Programs. Professor Mercouri Kanatzidis from Northwestern University and colleagues Kenneth Poeppelmeier, Sossina Haile, Steven Jacobsen and Danna Freedman are acquiring a single crystal X-ray diffractometer equipped with a silver micro-source, goniometer, and an efficient detector optimized for silver-radiation. In general, an X-ray diffractometer allows accurate and precise measurements of the full three-dimensional structure of a molecule, including bond distances and angles, and provides accurate information about the spatial arrangement of a molecule relative to neighboring molecules. The studies described here impact many areas, including organic and inorganic chemistry, materials chemistry and biochemistry. This instrument is an integral part of teaching as well as research and research training of undergraduate and graduate students in chemistry and biochemistry at this institution where students receive hands-on access to the diffractometers and collect data on their own experimental samples. The new diffractometer is also used for the biannual international Summer School co-organized with the American Crystallographic Association and Northwestern University. Collaborations are in place with other research institutions such as the University of Chicago, the Ohio State University, Illinois Institute of Technology, Loyola University Chicago, Lake Forest College and Roosevelt University.

The award is aimed at enhancing research and education at all levels. It is especially used for exploring solid state chemistry of chalcogenides and analyzing solid-state-related electrochemical processes. The diffractometer is also utilized for the analyses of synthesized compounds and minerals as well as synthesized oxides and oxide-fluorides. The instrument is employed in projects with applications in sustainable energy, geology, planetary sciences, ceramics and nanomaterials.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.