book review

Nanomaterials: An introduction to synthesis, properties, and applications, 2e
by Dieter Vollath
Wiley-VCH, 2013, 375 pages

Reviewed by T. Nelson

A nanomaterial is a material with building blocks smaller than 100 nanometers and whose properties depend on the small size. The goal of the author is to make the subject accessible to non-specialists without bogging the reader down with theory or quantum mechanics. The result is a highly readable and informative discussion of materials with amazing properties.

In fact, thin films, an early form of nano­mater­ials, have been around since the 1960s. One edition of Engineering Opportun­ities (a magazine that was so nicely illustrated my 7th grade art teacher tried to steal my copy) told us how they'd be the miracle material of the future. And sure enough, only sixty years later we now have nanodots, nanorods, and nanotubes.

This book has chapters on synthesis of nano­par­ticles, nanotubes, nanorods, nanofluids, and nanoplates, followed by chapters on their phase transfor­mations, magnetic, optical, electrical, and mechanical properties.

The author says that in many cases, nanoparticles have to be coated with a diffusion barrier like tin oxide, alumina, or PMMA to prevent them from touching and messing up the nano properties. A big challenge in synthesizing nanoparticles is that the materials tend to aggregate. The solution is to give them an electrical charge so the repelling force increases if they get bigger.

Nanomaterials have unexpected properties. Surface tension in multiwall fullerenes, for instance, causes the carbon to collapse to diamond. Fullerenes made of WS₂ vastly outper­form conven­tional lubricants even at low concentrations.

Normal graphite conducts electricity within its layers but not between them due to charged atoms on each layer. A single layer of graphite is called ‘graphene’ and is absolutely flat. Nanowires made of carbon nanotubes have enormously high conduc­tiv­ity, on the order of a trillion (10¹²) amperes per square meter. This happens because electrons in a nanowire move ballis­tic­ally, not by diffusion and scattering. So conduct­iv­ity is propor­tional to electron velocity and it depends only on the number of modes. That means it is stepwise or quantized instead of linear.

Quantum dots are superior to ordinary fluores­cent dyes because their emission is in a narrower band and because they're tunable. Aniso­tropic shapes like rods have two plasmon resonance modes: transverse and longitudinal. They interact with other molecules, making them good biosensors.

Photochromic materials such as WO₃, Nb₂O₅, and MoO₃ change color reversibly as a function of light intensity, making them useful as auto-dimming sunglasses and windows.

Perhaps the most interesting nano­materials are super­para­mag­netic particles, which allow the creation of enormously powerful magnets. They're also useful in magnetic cooling. In a magnetic fridge, particle spins heat up in a magnetic field. The excess heat is expelled in heat exchanger and the particles are allowed to cool down adiabat­ically. You can get cooling almost to absolute zero. A magnetic refriger­ator avoids the need for freon and uses 40% less power than a regular fridge. The only disadvan­tage is the need for a 1 Tesla magnetic field, which is in the range of a small MRI machine, so if you put one in your kitchen you'd have to be careful about metal objects like forks and frying pans suddenly launching themselves into the air. But that happens a lot in many homes already.

To measure whether a particle is super­para­mag­netic, you need to do Möss­bauer spectro­scopy, which is nicely explained as well. Almost no math is used, except as an aid to under­standing. All in all, an outstanding introduction to a fascinating branch of technology.

aug 08, 2025