Reviews & Analysis

Colloidal crystals assembled on the surface of a spherical water droplet contain 'scars', a macroscopic equivalent of conventional grain boundaries. Direct observation of these grain-boundary scars provides a new way of studying dislocation dynamics

The properties of most materials are intimately connected to the way in which they are ordered on the atomic scale. A new study suggests that in materials made from the regular three-dimensional arrangement of discrete nanocrystals, control of order and periodicity could be exploited at a whole new level.

Genetic algorithms prove useful to distil a complex quantum mechanical calculation of interatomic interactions down to its simplest mathematical expression. This makes it possible to predict the structure of new compounds from first principles.

The investigation of geometrically frustrated magnets can be complicated by crystalline disorder. New high-quality crystals of a Kagomé antiferromagnet offer neutrons a clearer path for determining their intrinsic order.

Materials that undergo a structural transformation between amorphous and crystalline phases under the influence of an electrical current have been known for decades. But with the discovery of new phase-change materials and new device configurations to make them switch, interest in them is being rejuvenated.

A new design of a gas cell based on advanced fibre-optic solutions overcomes the practical difficulties that have so far hindered the use of gas-phase materials in optical science and technology.

Wrinkling is a ubiquitous form of mechanical instability, occurring in such widely different systems as skin and lava flows. Hierarchical wrinkling leading to topographical features, with length scales spanning five orders of magnitude, has now been observed and harnessed in an artificial skin.

The concept of a Luttinger liquid has recently been established as vital to our understanding of the behaviour of one-dimensional quantum systems. Although this has led to a number of theoretical breakthroughs, only now has its descriptive power been confirmed experimentally.

The performance of conventional longitudinal and perpendicular magnetic recording media will soon reach their limits. The use of tilted media should allow unprecedented storage densities, thermal stability and fast switching speeds.

Reversible photochromism — based on a simple isomerization reaction — is heavily hindered when photochromic dyes are enclosed in polymer matrices. Tethering the dye to a flexible low-melting-point oligomer solves the problem.

Immobilization of membrane-bound proteins in inorganic matrices could allow creation of materials capable of mimicking biological processes. Advances in sol–gel biocomposites have now allowed development of a material that can use light to drive biosynthesis of ATP.

To date, nanoparticles and their simple assemblies have attracted interest from many branches of science. The next step entails building complex structures with these particles in the way that atoms and molecules are put together in nature. Materials scientists may soon find a whole new set of building blocks in their toolbox.

Silicon nanocrystals provide efficient means of generating light that is both tunable and compatible with conventional microelectronics. However, progress has been hampered by difficulties in achieving efficient carrier injection. A new approach could provide the solution.