Glasses and the glass transition
Published:January 01, 2001
Silicate glasses have existed for eons. The oldest specimens, which have been lying on the surface of the Moon for 4 billion years, display a wide range cf chemical compositions (Reid et al., 1973) and are a testimony of the early, intensive volcanic activity of our satellite. On the Earth the geological conditions for glass preservation are of course less good, bu; glasses bearing a few hundred million years are not uncommon. Better known are obsidians, which have been used very early by Man for making tools, or the basaltic glasses formed at the surface of pillow lavas when the magmas coming up at the mid-ocean ridges are suddenly cooled by oceanic waters (e.g., Langmuir et al., 1977). Geochemical interest in glasses dates back only to the 1970’s, however, and it mainly stems from the fact that glasses constitute a fruitful starting point for investigating the structure and properties of melts (e.g., Stebbins et al., 1995).
Ever since they were first produced in the Middle East 4000 years ago, glasses have indeed been known to form through cooling of liquids. Glasses, in fact, gained a widespread practical importance only at the beginning of the present era when a major technological revolution resulted from the discovery in Syria–Palestine that they could be blown. But it is much later that a great many advances in the understanding of their properties have been brought by their innumerable practical uses.
Figures & Tables
Solid Solutions in Silicate and Oxide Systems
The EMU book series or notes, as they are called, were introduced to provide university teachers with up-to-date reviews in important, rapidly evolving areas of mineralogy, petrology and geochemistry. They are also meant to introduce scientists into special and often interdisciplinary fields of research. In this regard, a volume on solid solutions is current and sorely needed. The solid Earth, as well as many meteorites and the other solid planets, consists for the most part of mineral solid solutions. Research on solid solutions is extremely broad encompassing work in physics and chemistry, metallurgy, materials science and, last but not least, mineralogy and petrology. Hence, because the theme is so strongly interdisciplinary in nature, the workshop was organised to include solid state physicists, physical chemists, crystallographers, mineralogists and petrologists. The various chapters reflect some of this diversity and show what mineralogy has become. Experimental investigations in mineralogy now routinely include different types of spectroscopies along with more traditional phase equilibrium, X-ray diffraction, calorimetry, and TEM methods. There have also been new and impressive developments in theory and computation. Many computational approaches relating to the study of solid solutions, for example, the Cluster Variation Method or Monte Carlo simulations, have been brought in from materials science, chemistry and physics. It can be concluded that the traditional or historical, and perhaps artificial, boundaries between the various disciplines are disappearing. Many current research efforts in mineralogy are similar to those in chemistry, materials science and physics.