1. Introduction. There is much interest in the general subject of porous inorganic materials with respect to their use as sorbents or catalysts. Such inorganic solids may be microporous, mesoporous or macroporous according to the sizes of the pores within the solid. Often there is a range of pore sizes within any given solid and so there is special interest in the synthesis, characterisation and application of porous inorganic solids with well defined pores. Pores of diameter larger than 50 nm are generally termed macropores. Those with diameters of less than 2 nm are micropores and pores of intermediate size are called mesopores. Solids, which contain only mesopores, are correctly called mesoporous but very often there is a combination of different types of porosities within one given solid. The synthesis, characterisation and application of microporous solids is much more advanced than is the case with mesoporous substances. Moreover, the synthesis of crystalline mesoporous materials is one clear goal for the future but which has not been attained so far. Consequently, it is of interest to examine the current state of our knowledge of microporous materials and to examine how this may apply to mesoporous materials. Both catalytic and sorption processes could benefit from studies of mesoporous solids because the mesopores could permit diffusion of larger reactants or products than is the case in microporous materials. 2.

The holding of an Advanced Study Institute on the topic of "Solid State Batteries" at this time represented a logical progression in a series of NATO-sponsored events. Summer Schools at Belgerati, Italy in 1972 and Ajaccio, Corsica in 1975 on the topic of "Solid -State IOllics" dealt with fundamental aspects of solid-state electro chemistry and materials science. The application of specific solid ionic conductors played a significant role in the Science Committee Institute on "Materials for Advanced Batteries" held at Aussois, France in 1979. Interest in these and related fields has grown substantially over this period, and is sustained today. Research and development programmes exist within universities, governmental research laboratories and industry, worldwide and a series of international conferences and collaborations have been set up. Advanced batteries, both secondary and primary, have a potentially important role o play in the development of many areas of tech nology in the late 20th century and beyond. Applications include stationary storage, vehicle traction and remote power sources, as well as industrial and domestic cordless products and consumer and military electronics. The concept of an all-so lid-state battery is not new but, until recently, their performance has precluded their use in other than specialist low power, primary, applications. Recent materials' developments, however, make the solid-state battery a real possibility in all of the application sectors mentioned above. Further, such cells offer many attractive features over alternative present-day and advanced systems."

The holding of an Advanced Study Institute on the topic of "Solid State Batteries" at this time represented a logical progression in a series of NATO-sponsored events. Summer Schools at Belgerati, Italy in 1972 and Ajaccio, Corsica in 1975 on the topic of "Solid -State IOllics" dealt with fundamental aspects of solid-state electro chemistry and materials science. The application of specific solid ionic conductors played a significant role in the Science Committee Institute on "Materials for Advanced Batteries" held at Aussois, France in 1979. Interest in these and related fields has grown substantially over this period, and is sustained today. Research and development programmes exist within universities, governmental research laboratories and industry, worldwide and a series of international conferences and collaborations have been set up. Advanced batteries, both secondary and primary, have a potentially important role o play in the development of many areas of tech nology in the late 20th century and beyond. Applications include stationary storage, vehicle traction and remote power sources, as well as industrial and domestic cordless products and consumer and military electronics. The concept of an all-so lid-state battery is not new but, until recently, their performance has precluded their use in other than specialist low power, primary, applications. Recent materials' developments, however, make the solid-state battery a real possibility in all of the application sectors mentioned above. Further, such cells offer many attractive features over alternative present-day and advanced systems."

1. Introduction. There is much interest in the general subject of porous inorganic materials with respect to their use as sorbents or catalysts. Such inorganic solids may be microporous, mesoporous or macroporous according to the sizes of the pores within the solid. Often there is a range of pore sizes within any given solid and so there is special interest in the synthesis, characterisation and application of porous inorganic solids with well defined pores. Pores of diameter larger than 50 nm are generally termed macropores. Those with diameters of less than 2 nm are micropores and pores of intermediate size are called mesopores. Solids, which contain only mesopores, are correctly called mesoporous but very often there is a combination of different types of porosities within one given solid. The synthesis, characterisation and application of microporous solids is much more advanced than is the case with mesoporous substances. Moreover, the synthesis of crystalline mesoporous materials is one clear goal for the future but which has not been attained so far. Consequently, it is of interest to examine the current state of our knowledge of microporous materials and to examine how this may apply to mesoporous materials. Both catalytic and sorption processes could benefit from studies of mesoporous solids because the mesopores could permit diffusion of larger reactants or products than is the case in microporous materials. 2.