Preface: Overview of the forum on functional inorganic materials.

Inorganic Chemistry is pleased to present a Forum on Functional Inorganic Materials. A recent workshop sponsored by the National Science Foundation highlighted these materials and their technological impact (Prog. Solid State Chem. 2008, 36, 1-133). As the report makes clear, we are presently at the halfway point of the solid-state century [The Solid State Century. Sci Am. 1997, 8 (1)], in which, to date, functional inorganic materials have played profound societal and technological roles. It is without question that new functional inorganic materials will be indispensible during the second half of the solid-state century. In addition, the Department of Energy recently published their Grand Challenges for Basic Energy Sciences (http://www.science. doe.gov/bes/reports/list.html). Successfully meeting the challenges described in their report will require the synthesis and characterization of new and advanced functional inorganic materials. Rapidly changing technologies, for example, associated with cell phones, digital video devices, and computers, continue to drive the discovery of new materials. The replacement of SiO2 as a high dielectric constant (high-κ) material in transistors is crucial if additional microelectronic miniaturization is to be achieved. Currently, hafnium-based oxides and oxynitrides show promise, but it remains an ongoing challenge to discover new high-κ materials. What exactly defines an inorganic material, or for that matter any material, as functional? One broad definition would encompass materials that exhibit properties important to a new or changing technological advance. Functional inorganic materials encompass a vast and growing field, and it is not possible to present all of the ongoing research in one Forum. As part of this important multidisciplinary subject, this Forum on Functional Inorganic Materials deals mainly with oxides and other solid-state materials. Functional inorganic materials are found in batteries and fuel cells, computer memories, sensors, and thermoelectrics. In addition, microporous and open-framework materials including zeolites and metalorganic framework (MOF) compounds increasingly are used in heterogeneous catalysis and gas storage. Materials such as Nd:YAG and GaN are utilized for infrared and blue laser applications. Functional inorganic materials are not limited to nonmolecular compounds and also include numerous molecular compounds. A. F. Wells in his fifth edition of Structural Inorganic Chemistry stated that “the structural [functional] side of inorganic chemistry cannot be put on a sound basis until the knowledge gained from the study of the solid state [molecular and nonmolecular] has been incorporated into chemistry as an integral part of the subject”. A host of other attributes including the oxidation state, ion size, crystallographic order or disorder, coordination number, and symmetry, play a key role in determining the functionality of an inorganic material. The complex associations between these attributes and compound functionality must be fully understood if “rational materials design” is to be achieved.