R. Cava et al. Progress in Solid State Chemistry 30(2002)1-101 language and research culture. However, the need for increasing interaction is seen by both sides. The participants in the workshop strongly felt that areas of mutual interest can be further established, and that the development of multidisciplinary education programs is essential. One of the areas of potential common interest is the development of biosensors-in which biological components are joined to microelectronic substrates on order sense or relay signals or to initiate mechanical or biological activity. This area is only in its infancy and is clearly of great potential The interaction of living cells with solid state materials seems to offer limitless possibilities for the future. The nature of the interface between biological and solid state materials, and the design and manipulation of that interface to enhance function or interaction, are virtually completely unexplored. Finally, biology can impact solid state chemistry by influencing the design of materials to mimic the function of com- plex biological materials 1. 4. Energy storage and comversion The development of viable, long-term solutions to meet our energy needs that also maintain the quality of our environment remains one of the most critical challenges facing the scientific community. Solutions to this challenge increasingly depend on electrochemical processes in solids. Photovoltaics, fuel cells, thermoelectrics and bat- teries are all devices in which energy storage or conversion relies on a coupling of chemical and electrical phenomena within the solid state. Accordingly, advances in energy technology require that fundamental questions of charge and mass transfer through complex solids be answered, and that novel processing techniques be developed to implement strategies for micro-structure and/or crystal structure modi- fication. These themes arise in each of the many energy systems described in this section, specifically, membrane reactors, fuel cells, thermoelectrics, batteries, capaci- tors, photovoltaics, hydrogen storage media and superconductors While each type of energy conversion or storage device faces its own unique hallenges, each is in critical need of new materials with improved properties. Thus, a broad-based effort in materials discovery, guided by computational chemistry, and complemented with a similar effort in comprehensive architectural control of known materials is essential. The solid state chemist brings to bear on this problem the unique ability to synthesize new compounds which may exhibit inherently unusual properties, not only leading to improvements to conventional devices, for example better cathodes for lithium ion batteries, but also rendering entirely new and as of-yet un-envisioned devices possible. Fundamental advances, however, require the cooperative efforts of experts in fields ranging from solid state chemistry and electro- chemistry to solid state physics and materials science to ensure that material behav- is understood at the most fundamental level while potential new devices are rapidly developed The present status of those collaborations and future possibilities were discussed
6 R.J. Cava et al. / Progress in Solid State Chemistry 30 (2002) 1–101 language and research culture. However, the need for increasing interaction is seen by both sides. The participants in the workshop strongly felt that areas of mutual interest can be further established, and that the development of multidisciplinary education programs is essential. One of the areas of potential common interest is the development of biosensors—in which biological components are joined to microelectronic substrates on order sense or relay signals or to initiate mechanical or biological activity. This area is only in its infancy and is clearly of great potential. The interaction of living cells with solid state materials seems to offer limitless possibilities for the future. The nature of the interface between biological and solid state materials, and the design and manipulation of that interface to enhance function or interaction, are virtually completely unexplored. Finally, biology can impact solid state chemistry by influencing the design of materials to mimic the function of complex biological materials. 1.4. Energy storage and conversion The development of viable, long-term solutions to meet our energy needs that also maintain the quality of our environment remains one of the most critical challenges facing the scientific community. Solutions to this challenge increasingly depend on electrochemical processes in solids. Photovoltaics, fuel cells, thermoelectrics and batteries are all devices in which energy storage or conversion relies on a coupling of chemical and electrical phenomena within the solid state. Accordingly, advances in energy technology require that fundamental questions of charge and mass transfer through complex solids be answered, and that novel processing techniques be developed to implement strategies for micro-structure and/or crystal structure modi- fication. These themes arise in each of the many energy systems described in this section, specifically, membrane reactors, fuel cells, thermoelectrics, batteries, capacitors, photovoltaics, hydrogen storage media and superconductors. While each type of energy conversion or storage device faces its own unique challenges, each is in critical need of new materials with improved properties. Thus, a broad-based effort in materials discovery, guided by computational chemistry, and complemented with a similar effort in comprehensive architectural control of known materials is essential. The solid state chemist brings to bear on this problem the unique ability to synthesize new compounds which may exhibit inherently unusual properties, not only leading to improvements to conventional devices, for example, better cathodes for lithium ion batteries, but also rendering entirely new and asof-yet un-envisioned devices possible. Fundamental advances, however, require the cooperative efforts of experts in fields ranging from solid state chemistry and electrochemistry to solid state physics and materials science to ensure that material behaviour is understood at the most fundamental level while potential new devices are rapidly developed. The present status of those collaborations and future possibilities were discussed
R. Cava et al. Progress in Solid State Chemistry 30(2002)1-101 1. 5. Molecular. hybrid, and macromolecular materials The design, preparation, and study of physical properties of molecular assemblies nd polymeric molecule-based materials exhibiting useful magnetic, electrical, or optical properties is a very active area of worldwide research. The quest in this area is not just to obtain molecule-based compounds than can behave like classical materials, but also to produce materials that may exhibit completely new physical properties or those in which several properties are combined. Examples of such sys- tems could be materials showing electrical or magnetic bistability, tunable magnetic ordering temperatures, discrete molecules showing magnetic hysteresis (nanomagnets), and hybrid materials coupling more than one property, e.g. magnet- ism with conductivity/superconductivity, or magnetism with optical properties. Other interesting phenomena that may be studied are quantum tunneling effects, long-live hoto- optical excited states, and solids with restricted magnetic dimensionalities One frontier area in this research field is the evolution of new synthetic strategies to construct molecules at the mesoscale level and to specifically control their organi zation in solution and/or in the solid state. This includes the formation of thin layers and organized films, or their encapsulation/intercalation, etc, into solids. A second key area is the application of frontier experimental techniques to characterize the resulting materials and allow for the identification of the most interesting phenomena Finally, it is important to develop suitable theoretical models based on solid-state approaches as well as on molecular orbital approaches(ab initio and density func tional theory). The ultimate goal is an understanding of the properties of the materials that will lead to predictions about the nature of interactions in molecular/macromolecular assemblies. All these areas of research have been. and continue to be, of great interest in the study of the solid state chemistry of non- molecular compounds. There is an immeasurable potential benefit to both the solid state chemistry and molecular chemistry communities in greatly increasing the inter actions between these two areas of research The structural and chemical diversity of molecular compounds is unparalleled in the world of solid state chemistry. Mor be syr sized by rational synthetic strategies that are impossible to implement in the solid state. In light of these attributes, molecular compounds present almost unlimited possibilities for development of new materials with novel and complex physical properties. The potential for fruitful interactions with the solid state chemistry com munity also appear to be limitless, as molecular chemists become increasingly inter ested in the synthesis of new compounds with exotic magnetic and electronic proper ties and the correlation of those properties with chemistry and structure-areas of research that are at the very heart of traditional solid state chemistry. This section describes the potential for interactions in the areas of molecular precursor routes to materials, self-assembled and organic materials, molecular nanomagnets, composite and hybrid molecular materials (such as templated materials)and finally inorganic/organic hybrid materials
R.J. Cava et al. / Progress in Solid State Chemistry 30 (2002) 1–101 7 1.5. Molecular, hybrid, and macromolecular materials The design, preparation, and study of physical properties of molecular assemblies and polymeric molecule-based materials exhibiting useful magnetic, electrical, or optical properties is a very active area of worldwide research. The quest in this area is not just to obtain molecule-based compounds than can behave like classical materials, but also to produce materials that may exhibit completely new physical properties or those in which several properties are combined. Examples of such systems could be materials showing electrical or magnetic bistability, tunable magnetic ordering temperatures, discrete molecules showing magnetic hysteresis (nanomagnets), and hybrid materials coupling more than one property, e.g. magnetism with conductivity/superconductivity, or magnetism with optical properties. Other interesting phenomena that may be studied are quantum tunneling effects, long-lived photo-optical excited states, and solids with restricted magnetic dimensionalities. One frontier area in this research field is the evolution of new synthetic strategies to construct molecules at the mesoscale level and to specifically control their organization in solution and/or in the solid state. This includes the formation of thin layers and organized films, or their encapsulation/intercalation, etc., into solids. A second key area is the application of frontier experimental techniques to characterize the resulting materials and allow for the identification of the most interesting phenomena. Finally, it is important to develop suitable theoretical models based on solid-state approaches as well as on molecular orbital approaches (ab initio and density functional theory). The ultimate goal is an understanding of the properties of the materials that will lead to predictions about the nature of interactions in molecular/macromolecular assemblies. All these areas of research have been, and continue to be, of great interest in the study of the solid state chemistry of nonmolecular compounds. There is an immeasurable potential benefit to both the solid state chemistry and molecular chemistry communities in greatly increasing the interactions between these two areas of research. The structural and chemical diversity of molecular compounds is unparalleled in the world of solid state chemistry. Moreover, molecular compounds can be synthesized by rational synthetic strategies that are impossible to implement in the solid state. In light of these attributes, molecular compounds present almost unlimited possibilities for development of new materials with novel and complex physical properties. The potential for fruitful interactions with the solid state chemistry community also appear to be limitless, as molecular chemists become increasingly interested in the synthesis of new compounds with exotic magnetic and electronic properties and the correlation of those properties with chemistry and structure—areas of research that are at the very heart of traditional solid state chemistry. This section describes the potential for interactions in the areas of molecular precursor routes to materials, self-assembled and organic materials, molecular nanomagnets, composite and hybrid molecular materials (such as templated materials) and finally inorganic/organic hybrid materials
R. Cava et al. /Progress in Solid State Chemistry 30(2002)1-101 1.6. Nanoscale science and technology The synthesis and characterization of materials at the nanometer length scale has been an area of increasing vitality and importance in the past five years. New phenomena arise because the size of the resulting materials is on the same order as the fundamental interaction distances that give rise to physical properties. Great opportunities for the investigation of both fundamentally new physical phenomena and enabling new technologies lie ahead. At the heart of the revolution in nanoscale science has been the development by chemists of synthesis and assembly methods for making and manipulating new molecular and extended-structure materials on length scales previously inaccessible through conventional pathways. Sophisticated assembly methods allow for the synthesis and exploration of non-thermodynamic phase assemblages with designed-in physical properties. The potential for the devel opment of new materials with new properties appears almost limitless Synthesis of new materials and characterization of their properties is at the heart of solid state chemistry, and solid state chemists have had a significant role in the development of this area of research. The nanoscale science community extends well beyond the borders of the solid state chemistry community, however, and most of the important developments so far have been outside the traditional boundaries of our field. Significant opportunities lie in the further integration solid state community into the developments in nanoscale science The interactions between nanoscale science and solid state chemistry are strong Nanoscale science concerns itself with synthesizing and assembling matter at mul- tiple length scales-from atomic and molecular species, to individual nanoscale building blocks such as nanocrystals and nanowires, and then from these building blocks to larger scale e assem blies and systems. Solid important role in the first step of this process: putting atoms together into ordered 3-dimensional crystal lattices. The manner in which the properties of those crystalline structural units change their properties on changing their physical size into the nano- meter regime is of mutual interest to solid state chemists and nanoscale scientists Described in this section is state of the art knowledge in semiconductor nanoparticles, nanowires, nanotubes, and photonic crystals. The central challenge of the continued development of this field-the assembly of such nanoscale components into systems with unique physical properties or functions, an area of great potential interest to solid state chemists. is described 1.6.1. Theory and condensed matter physics Progress in understanding new phenomena in condensed matter physics is bes achieved through ingenious synthesis, in-depth characterization, and theoretical analysis of high quality, complex new materials. Through the process of materials synthesis, intimately linked to materials theory and definitive characterization, further new phenomena are dreamed of, pursued, discovered, characterized, and ultimately extrapolated to even more surprising discoveries. High temperature superconductors and quantum spin liquid magnetic insulators provide examples of unexpected proper ties that emerge only when the systems become sufficiently complex, but this com-
8 R.J. Cava et al. / Progress in Solid State Chemistry 30 (2002) 1–101 1.6. Nanoscale science and technology The synthesis and characterization of materials at the nanometer length scale has been an area of increasing vitality and importance in the past five years. New phenomena arise because the size of the resulting materials is on the same order as the fundamental interaction distances that give rise to physical properties. Great opportunities for the investigation of both fundamentally new physical phenomena and enabling new technologies lie ahead. At the heart of the revolution in nanoscale science has been the development by chemists of synthesis and assembly methods for making and manipulating new molecular and extended-structure materials on length scales previously inaccessible through conventional pathways. Sophisticated assembly methods allow for the synthesis and exploration of non-thermodynamic phase assemblages with designed-in physical properties. The potential for the development of new materials with new properties appears almost limitless. Synthesis of new materials and characterization of their properties is at the heart of solid state chemistry, and solid state chemists have had a significant role in the development of this area of research. The nanoscale science community extends well beyond the borders of the solid state chemistry community, however, and most of the important developments so far have been outside the traditional boundaries of our field. Significant opportunities lie in the further integration of the solid state community into the developments in nanoscale science. The interactions between nanoscale science and solid state chemistry are strong. Nanoscale science concerns itself with synthesizing and assembling matter at multiple length scales—from atomic and molecular species, to individual nanoscale building blocks such as nanocrystals and nanowires, and then from these building blocks to larger scale assemblies and systems. Solid state chemistry plays an important role in the first step of this process: putting atoms together into ordered 3-dimensional crystal lattices. The manner in which the properties of those crystalline structural units change their properties on changing their physical size into the nanometer regime is of mutual interest to solid state chemists and nanoscale scientists. Described in this section is state of the art knowledge in semiconductor nanoparticles, nanowires, nanotubes, and photonic crystals. The central challenge of the continued development of this field—the assembly of such nanoscale components into systems with unique physical properties or functions, an area of great potential interest to solid state chemists, is described. 1.6.1. Theory and condensed matter physics Progress in understanding new phenomena in condensed matter physics is best achieved through ingenious synthesis, in-depth characterization, and theoretical analysis of high quality, complex new materials. Through the process of materials synthesis, intimately linked to materials theory and definitive characterization, further new phenomena are dreamed of, pursued, discovered, characterized, and ultimately extrapolated to even more surprising discoveries. High temperature superconductors and quantum spin liquid magnetic insulators provide examples of unexpected properties that emerge only when the systems become sufficiently complex, but this com-
R. Cava et al. Progress in Solid State Chemistry 30(2002)1-101 plexity can make further progress very difficult. The solid state chemistry community has the potential to play a much more active role in this process Solid state physics and solid state chemistry have long had strongly overlapping interests, and have been growing closer together for a few decades. Many of the materials of intense current interest in condensed matter physics are also of interest to solid state chemists. This section describes materials such as manganites, novel superconductors, multiferroics, dilute magnetic semiconductors, magnetic insulators, half metallic ferromagnets, correlated electron materials, and battery materials, appearing certain to attract growing mutual interest in the near future. The impact of theory, modeling, and computation have been growing rapidly in solid state chem istry, but their potential to change the field profoundly is yet to be fully exploited Finally, the central importance of new materials to condensed matter physics can hardly be overstated. Great opportunities in materials exploration lie in strengthening es between solid state chemistry and solid state physics, building more intimate connections, and establishing strong feedback between computation and experiment Finally, solid state chemists have the potential to impact condensed matter physics deeply through the growth of high quality single crystals and ultrapure materials 1.7. National facilities The Us has made a considerable investment in synchrotron X-ray and neutron scattering capabilities, as well as other facilities such as the National High Field Magnet Laboratory. They represent a valuable resource for the characterization of new and potentially technologically important materials. However, the use of these facilities by solid-state chemists is not as widespread as it could be. This may in part be because solid-state chemists are not aware of the contributions that such facilities can make to their research. However, it also seems likely that the"activation barrier"associated with central facility use deters many scientists from using them Our national facilities generally do a good job of serving expert users, but they do not al ways meet the needs of occasional (and inexperienced)users with good scientific problems. This session examined how we can improve the link between solid-state chemists and the national facilities community. Current and future capabilities that may be of interest to solid-state chemists were described, and possible strategies for improving accessibility and ease of use were presented Major research facilities, such as the high field magnet laboratory, and the nations neutron and synchrotron X-ray centers, are very important resources for the solid state chemistry community. The participants in the workshop emphasized the impor tance of using these facilities effectively and productively. This section of the report outlines the variety of such facilities, and suggests some measures to enhance the fficiency and productivity of these facilities. The issues discussed include training and supporting users while they are working at facilities, the effective education of potential users, tailoring the user access process to better meet the needs of the scientific community, the development of new instrumentation, dedicated versus multipurpose instrumentation, and remote access to instruments. A series of rec-
R.J. Cava et al. / Progress in Solid State Chemistry 30 (2002) 1–101 9 plexity can make further progress very difficult. The solid state chemistry community has the potential to play a much more active role in this process. Solid state physics and solid state chemistry have long had strongly overlapping interests, and have been growing closer together for a few decades. Many of the materials of intense current interest in condensed matter physics are also of interest to solid state chemists. This section describes materials such as manganites, novel superconductors, multiferroics, dilute magnetic semiconductors, magnetic insulators, half metallic ferromagnets, correlated electron materials, and battery materials, appearing certain to attract growing mutual interest in the near future. The impact of theory, modeling, and computation have been growing rapidly in solid state chemistry, but their potential to change the field profoundly is yet to be fully exploited. Finally, the central importance of new materials to condensed matter physics can hardly be overstated. Great opportunities in materials exploration lie in strengthening ties between solid state chemistry and solid state physics, building more intimate connections, and establishing strong feedback between computation and experiment. Finally, solid state chemists have the potential to impact condensed matter physics deeply through the growth of high quality single crystals and ultrapure materials. 1.7. National facilities The US has made a considerable investment in synchrotron X-ray and neutron scattering capabilities, as well as other facilities such as the National High Field Magnet Laboratory. They represent a valuable resource for the characterization of new and potentially technologically important materials. However, the use of these facilities by solid-state chemists is not as widespread as it could be. This may in part be because solid-state chemists are not aware of the contributions that such facilities can make to their research. However, it also seems likely that the “activation barrier” associated with central facility use deters many scientists from using them. Our national facilities generally do a good job of serving expert users, but they do not always meet the needs of occasional (and inexperienced) users with good scientific problems. This session examined how we can improve the link between solid-state chemists and the national facilities community. Current and future capabilities that may be of interest to solid-state chemists were described, and possible strategies for improving accessibility and ease of use were presented. Major research facilities, such as the high field magnet laboratory, and the nation’s neutron and synchrotron X-ray centers, are very important resources for the solid state chemistry community. The participants in the workshop emphasized the importance of using these facilities effectively and productively. This section of the report outlines the variety of such facilities, and suggests some measures to enhance the efficiency and productivity of these facilities. The issues discussed include training and supporting users while they are working at facilities, the effective education of potential users, tailoring the user access process to better meet the needs of the scientific community, the development of new instrumentation, dedicated versus multipurpose instrumentation, and remote access to instruments. A series of rec-
R. Cava et al. Progress in Solid State Chemistry 30(2002)1-101 ommendations are made that focus on increasing the value of these facilities to the scientific community in general and solid state chemists in particular 2. Earth, planetary, and environmental science Alexandra Navrotsky. Peter Burns 2. 1. Linking Earth science and solid state chemistry Mineralogical research largely focuses on the structures, chemistry and occur- rences of naturally occurring inorganic compounds. It is, in a sense, inorganic natural products chemistry. Minerals are unique in that they are the subset of inorganic compounds that are sufficiently compatible with their surroundings to persist for geologic time and that have compositions compatible with the elemental abundances and geochemistry of the Earth. Thus it is no surprise that mineralogy has many commonalities with solid state chemistry, especially in the realm of materials charac terization. Mineralogists typically are expert crystallographers, and contribute a unique understanding of complex inorganic structures. They deal with diverse chemi- cal systems, and have an appreciation of the interaction between complex mineral assemblages and geologic fluids. Earth scientists deal with time scales and distance scales far more diverse than those accessed by direct human experience or by techno- logical processes A Many materials are important both in the Earth and in technological applications ble 1 lists some of these Furthermore. minerals are the raw materials on which technology depends. The distribution, discovery and mining of ores and other raw materials pose critical technological, social, and political issues. Impending real or Table Materials of interest to both Earth science and materials science Material Nature of interest and application Earth science Solid state chemistry Hydrogen Jupiter and other giant planets energy storage Earth’ s core Perovskites Iron oxides nvironmental science nagnetic recording Manganese oxides nvironmental science Zeolites on exchange Clays nvironmental science structural materials Silicate melts Titania nmental science paints, solar cells, catalysts
10 R.J. Cava et al. / Progress in Solid State Chemistry 30 (2002) 1–101 ommendations are made that focus on increasing the value of these facilities to the scientific community in general and solid state chemists in particular. 2. Earth, planetary, and environmental science Alexandra Navrotsky, Peter Burns 2.1. Linking Earth science and solid state chemistry Mineralogical research largely focuses on the structures, chemistry and occurrences of naturally occurring inorganic compounds. It is, in a sense, inorganic natural products chemistry. Minerals are unique in that they are the subset of inorganic compounds that are sufficiently compatible with their surroundings to persist for geologic time and that have compositions compatible with the elemental abundances and geochemistry of the Earth. Thus it is no surprise that mineralogy has many commonalities with solid state chemistry, especially in the realm of materials characterization. Mineralogists typically are expert crystallographers, and contribute a unique understanding of complex inorganic structures. They deal with diverse chemical systems, and have an appreciation of the interaction between complex mineral assemblages and geologic fluids. Earth scientists deal with time scales and distance scales far more diverse than those accessed by direct human experience or by technological processes. Many materials are important both in the Earth and in technological applications. Table 1 lists some of these. Furthermore, minerals are the raw materials on which technology depends. The distribution, discovery and mining of ores and other raw materials pose critical technological, social, and political issues. Impending real or Table 1 Materials of interest to both Earth science and materials science Material Nature of interest and application Earth science Solid state chemistry Hydrogen Jupiter and other giant planets energy storage Iron Earth’s core steel industry Perovskites Earth’s mantle electronic materials Iron oxides environmental science magnetic recording Manganese oxides environmental science catalysts Zeolites environmental science catalysts ion exchange ion exchange Clays environmental science ceramics industry petroleum structural materials Silicate melts volcanism slags, glasses Titania environmental science paints, solar cells, catalysts