Layer silicate materials and clays

Clay science covers an extensive array of basic, applicative and interconnected subject areas. These subjects range from quantum-mechanical modelling of the structure of layer silicates to industrial applications of clays and the origin of life on Earth, from clay–mineral relationships to terrestrial climate change, and from clay minerals to extraterrestrial environments, to mention a few.

However, have all the definitive questions on clays been answered? Have all crucial observations been performed? Have the stability fields of clay minerals been adequately described? Are the chemical and physical properties of clays understood, and can these properties be engineered and exploited for useful applications? In addition, has our knowledge of clays been sufficiently communicated to the wider scientific community and the general public?

These and other questions were examined and debated during the 14th International Clay Conference (ICC) “Micro et Nano - Scientiae Mare Magnum”, which was held in Castellaneta Marina (Taranto province), Italy, between 14th and 20th June 2009. The conference offered the scientific community an opportunity to review and update the progress made in clay science over the last few years and to identify the goals to be set for future clay research.

The 14th ICC was organised by the Associazione Italiana per lo Studio delle Argille (AISA), on behalf of the “Association Internationale pour l’Étude des Argiles–AIPEA” 1,2.

Saverio Fiore, the Conference Chair, and the dynamic local organising committee (Angelo Aromando, Jessica Bellanova, Claudia Belviso, Francesco Cavalcante, Fortunato De Santis, Felice Finizio, Gina Giannossi, Rocco Laviano, Antonio Lettino, Luca Medici, Donato Perniola, Piero Ragone, Maria Cristi Sansone, Vito Summa, Fabio Tateo) hosted one of the largest clay conferences ever, with 1028 submitted abstracts. Over 600 clay scientists from 49 countries were present, with six plenary lectures, 42 keynote lectures, 24 invited presentations, and 408 oral and 548 poster contributions; the scope of the conference demonstrated the vitality of the international clay-science community.

Contributions were organised into eight main themes: Bio-clays interface and life's origin, Ceramics and engineering, Geology and geochemistry, Health and environment, Mineralogy and crystallography, Nano and porous materials, Soils and sediments, and Miscellanea. The themes were further subdivided to produce a total of 43 sessions. The sessions covered topics such as Clays and biomolecules: from the origin of life to medical applications; Colloids and rheology; Clay minerals and climate change; Stability of clay minerals in geological radioactive waste disposal; Interaction of CO₂ with clay minerals; Clay minerals in extraterrestrial environments; Simulation of clay mineral structures and interfaces; Polymer–clay nanocomposites; Industrial application of nanoclays. Of course, this list does not encompass all the topics covered during the conference. However, the list represents a general overview of the subjects and gives a flavour of the variability and intriguing characteristics of clay science and its applications.

Philosophical Magazine publishes contributed articles in the field of condensed matter, describing original results, theories and concepts relating to the structure and properties of crystalline materials, ceramics, polymers, glasses, amorphous films, composites, and soft matter. Coverage of phase transitions, nanotechnology, and novel materials is envisaged and further development is expected on, for example, soft condensed matter and, in particular, the interface between hard and soft matter.

This Special Issue collects some selected works of “Clay Science” with the purpose of showing the wide range of applications and/or new fields, or recent relevant achievements in traditional, well-established subjects, or prospects for future developments, all related to material sciences. These works were submitted to the following sessions: Bio-clays interface and life's origin, Mineralogy and crystallography, Ceramics and engineering, and Nano and porous materials.

In more detail, this issue includes the following contributions: Sources and sinks of clay minerals on Mars, presented by R. Milliken and D. Bish 3; Biomass and habitability potential of clay minerals- and iron-rich environments: Testing novel analogs for the Mars Science Laboratory landing sites candidates, by R. Bonaccorsi and co-workers 4; Role of clays in the prebiotic synthesis of sugar derivatives from formamide, by R. Saladino and co-workers 5; Supercritical fluid behavior at nanoscale interfaces: Implications for CO₂ sequestration in geologic formations, by D.R. Cole and co-workers 6; Mobility of adsorbed Cry1Aa insecticidal toxin from Bacillus thuringiensis (Bt) on montmorillonite measured by fluorescence recovery after photobleaching (FRAP), by H. Quiquampoix and co-workers 7; Mg- and K-exchange cation effects on the XRD analysis of soil clays, by P. Aparicio and co-workers 8; Effect of chemical composition and swelling on acid dissolution of 2 : 1 clay minerals, by P. Komadel and co-workers 9; Dielectric properties of micaceous clays determined by terahertz time-domain spectroscopy, by M. Janek and co-workers 10; Structure and cleavage energy of surfactant-modified clay minerals: Influence of CEC, head group, and chain length, by H. Heinz and Y.T. Fu 11; Phase transitions in natural zeolites and the importance of P(H₂O), by D. Bish and H.W. Wang 12; On the high-temperature structural behaviour of talc, Mg₃Si₄O₁₀(OH)₂ up to 1600°C: Effect of mechanical deformation and strain, by F. Dellisanti and G. Valdrè 13; Ab initio molecular dynamics study of hydronium complexation in Na-montmorillonite, by S. Churakov and G. Kosakowsky 14; Molecular dynamics computer simulations of the effects of hydrogen bonding on the properties of layered double hydroxides intercalated with organic acids, by A. Kalinichev and co-workers 15; Clay exfoliation in polymer nanocomposites: Specific chemical reactions and exchange of specialty modifications on clay surface, by V. Mittal 16; Phase transition of conducting polymer/clay nanocomposite suspensions under electric field, by H.J. Choi and co-workers 17; Fabrication of composites consisting of clay mineral–dye composites as nonlinear optical materials, by J. Kawamata and co-workers 18; Ultrathin films of clay–protein composites, by R. Schooneydt and co-workers 19.

I thank all the contributors for their enthusiastic participation and support for this issue. I also express sincere thanks to the 50 referees for their invaluable help during the reviewing process.

Special thanks are due to the Chair of the 14th International Clay Conference, Saverio Fiore, and to the Editorial Board of Philosophical Magazine for affording me the opportunity to organise this special issue “Layer silicate materials and clays” of Philosophical Magazine.

Finally, I gratefully acknowledge financial support from The University of Bologna “Alma Mater Studiorum”, Italy.