My goodness, what are “smart electronic materials”? In his introduction, Dr Singh states that humans have used smart materials for thousands of years. They are materials that respond to input with a well‐defined output. He suggests that the mud on a jungle trail is smart if it takes the imprint of an animal's foot, because a man can later tell what kind of animal it was and even its size and weight. In the case of electronics materials, they are defined as those which undergo a predictable change when subjected to a stimulus. The author divides the subject into semiconductors, ferroelectrics, ferromagnetics, piezoelectrics and some polymers.
He opens the book with a discussion on crystalline and non‐crystalline materials, the latter divided into polycrystalline, amorphous, glassy, liquid crystal and organic materials. This is followed by quantum mechanics and electronic levels, the latter with some emphasis on electrons and charges in crystalline and other solids (conductors, superconductors, insulators, semiconductors). The practical applications of each subject are mentioned, such as the mobility of TFTs in displays or the use of ceramics in gas sensors. Up to this point, though, the treatment has been fairly general.
The fifth chapter deals with devices that absorb and emit light, for example, light detectors, solar cells, LEDS, laser diodes and polymeric devices, such as may be used for backlighting the display of a cellular telephone. I found the next chapter particularly interesting. It is entitled Dielectric response: polarization effects. It is here that I could relate to what I know about the performance of printed circuit substrates and their sometimes apparently anomalous behaviour. Of course, it also deals with piezoelectricity, pyroelectricity and similar effects. Modern communications and electronics depend largely on light propagation in materials, e.g. data switching and modulation in fibre optics and in LCD displays.
Clearly, the magnetic effects in solids play an enormous role in modern electronics, whether in remanent components, such as the surface layers in hard discs, or in “soft” material, such as some ferrites. However, the study goes further into fields from superconductors, magnetic effects in semiconductors and so on. I was not aware that extremely low temperatures could be obtained by switching off the magnetic field in a material, provided the entropy remained constant, or that light polarisation could be rotated by applying magnetic fields to some crystals, such as some garnets.
Appendices offer further information on the properties of semiconductors; a treatise on p‐n junctions; the Fermi Golden Rule; lattice vibrations and phonons; and defect scattering and mobility.
The book is well presented and produced (Plate 1). The many diagrams are clear. The indexing is more than adequate. Each of the eight chapters is concluded with a graphic summary, some problems for the student (the answers can be found on the internet) and some references for further reading. It was a privilege to be able to explore some new fields that I had not studied as an engineer or even in the post‐graduate courses in physics that I took.
This work addresses itself primarily to first‐year graduate students but I feel that it is also of immense interest to those of us in our industry who are concerned with materials. It does require a good grasp of physics and mathematics to fully understand it (I got lost at times!). Having read this impressive work, the question may arise as to when a material can be classified as “smart” because some of the undesirable features of “unsmart” materials may be explained by an unwitting “smartness”!
