November 2012 Volume 11, Issue 11

Editorial

Alternative metrics   p907
doi:10.1038/nmat3485
As the old 'publish or perish' adage is brought into question, additional research-impact indices, known as altmetrics, are offering new evaluation alternatives. But such metrics may need to adjust to the evolution of science publishing.

Correspondence

Progress towards an all-renewable electricity supply   pp908 - 909
Keith Barnham, Kaspar Knorr and Massimo Mazzer
doi:10.1038/nmat3466

Research Highlights

Rust shines in new light | Particle perfection | Defect-less melting | Enzyme catalysis | Frosty reaction

News and Views

Review

From metamaterials to metadevices   pp917 - 924
Nikolay I. Zheludev and Yuri S. Kivshar
doi:10.1038/nmat3431
Metamaterials are man-made structures that allow optical properties to be shaped on length scales far smaller than the wavelength of light. Although metamaterials were initially considered mainly for static applications, this Review summarizes efforts towards an active functionality that enables a much broader range of photonic device applications.

Letters

Hidden polymorphs drive vitrification in B₂O₃    pp925 - 929
Guillaume Ferlat, Ari Paavo Seitsonen, Michele Lazzeri and Francesco Mauri
doi:10.1038/nmat3416
Whether a liquid forms a crystal or a glass on solidification depends on many factors. The finding now that a disordered structure is favoured in B₂O₃ because the system cannot choose between several crystalline polymorphs of similar energy highlights a link between glass formation and crystallization.

Atomic-scale determination of surface facets in gold nanorods   pp930 - 935
Bart Goris, Sara Bals, Wouter Van den Broek, Enrique Carbó-Argibay, Sergio Gómez-Graña, Luis M. Liz-Marzán and Gustaaf Van Tendeloo
doi:10.1038/nmat3462
The atomic structure of nanoparticles considerably influences their properties. A new methodology that is now able to measure the full three-dimensional atomic structure of free-standing nanoparticles will therefore provide a much better connection between their structure and properties.

See also: News and Views by Arslan & Stach

Switching terahertz waves with gate-controlled active graphene metamaterials   pp936 - 941
Seung Hoon Lee, Muhan Choi, Teun-Teun Kim, Seungwoo Lee, Ming Liu, Xiaobo Yin, Hong Kyw Choi, Seung S. Lee, Choon-Gi Choi, Sung-Yool Choi, Xiang Zhang and Bumki Min
doi:10.1038/nmat3433
The properties of graphene have been widely studied for applications in electronics. Expanding its use in photonics as well, it is now demonstrated that the propagation of terahertz waves can be electronically switched by such a single atomic layer of carbon.

Nanostructured high-energy cathode materials for advanced lithium batteries   pp942 - 947
Yang-Kook Sun, Zonghai Chen, Hyung-Joo Noh, Dong-Ju Lee, Hun-Gi Jung, Yang Ren, Steve Wang, Chong Seung Yoon, Seung-Taek Myung and Khalil Amine
doi:10.1038/nmat3435
Nickel-rich layered lithium transition metal oxides have been investigated as high-energy cathode materials for rechargeable lithium batteries because of their high specific capacity and relatively low cost. Such an oxide with high capacity (215 mA h g^-1), where the nickel concentration decreases linearly whereas the manganese concentration increases linearly from the centre to the outer layer of each particle, is now proposed.

Fractionalization of interstitials in curved colloidal crystals   pp948 - 951
William T. M. Irvine, Mark J. Bowick and Paul M. Chaikin
doi:10.1038/nmat3429
Understanding the consequences of the interplay of defects and local curvature in crystals is far from complete despite the considerable influence that a defect has on the crystal’s local properties. It is now found that interstitials inserted in curved crystals at oil/glycerol interfaces can fractionate into two dislocations, which glide through the lattice in opposite directions until they get absorbed into existing dislocations, scars or pleats.

See also: News and Views by Reichhardt & Reichhardt

Articles

Role of vacancies in metal–insulator transitions of crystalline phase-change materials   pp952 - 956
W. Zhang, A. Thiess, P. Zalden, R. Zeller, P. H. Dederichs, J-Y. Raty, M. Wuttig, S. Blügel and R. Mazzarello
doi:10.1038/nmat3456
Phase-change materials show an unusual metal–insulator transition that is induced by disorder in the crystalline state. Numerical computations now show how the transition to the metallic state proceeds from the dissolution of electronic states situated at vacancy clusters to the formation of ordered vacancy layers.

Bulk electronic structure of the dilute magnetic semiconductor Ga_1−xMn_xAs through hard X-ray angle-resolved photoemission   pp957 - 962
A. X. Gray, J. Minár, S. Ueda, P. R. Stone, Y. Yamashita, J. Fujii, J. Braun, L. Plucinski, C. M. Schneider, G. Panaccione, H. Ebert, O. D. Dubon, K. Kobayashi and C. S. Fadley
doi:10.1038/nmat3450
The origin of the magnetism in manganese-doped gallium arsenide has been the subject of much debate. Now, hard X-ray angle-resolved photoemission has been used to probe the electronic structure of this material and clarify the mechanism through which the magnetism arises.

Engineering the surface structure of MoS₂ to preferentially expose active edge sites for electrocatalysis   pp963 - 969
Jakob Kibsgaard, Zhebo Chen, Benjamin N. Reinecke and Thomas F. Jaramillo
doi:10.1038/nmat3439
Controlling surface structure at the atomic scale is paramount to developing effective catalysts. The surface structure of MoS₂ is now engineered to preferentially expose edge sites by successfully synthesizing contiguous large-area thin films of a highly ordered double-gyroid MoS₂ bicontinuous network with nanoscale pores.

Tuning the catalytic activity of Ag(110)-supported Fe phthalocyanine in the oxygen reduction reaction   pp970 - 977
F. Sedona, M. Di Marino, D. Forrer, A. Vittadini, M. Casarin, A. Cossaro, L. Floreano, A. Verdini and M. Sambi
doi:10.1038/nmat3453
A major obstacle to fully understanding the catalytic mechanisms of oxygen reduction reactions and to designing more efficient catalysts is the lack of detailed information about the active site structure. Molecular local chemisorption sites and the long-range supramolecular arrangement of metallophthalocyanine molecules on a metal surface can now be controlled by the fine tuning of the overlayer coverage.

Ultrasensitive detection of toxic cations through changes in the tunnelling current across films of striped nanoparticles   pp978 - 985
Eun Seon Cho, Jiwon Kim, Baudilio Tejerina, Thomas M. Hermans, Hao Jiang, Hideyuki Nakanishi, Miao Yu, Alexander Z. Patashinski, Sharon C. Glotzer, Francesco Stellacci and Bartosz A. Grzybowski
doi:10.1038/nmat3406
Solid-state sensors for the detection of heavy-metal cations require for the most part sophisticated chemistry and equipment. It is now shown that toxic cations in environmental samples can be detected with ultrahigh sensitivity and over a broad range of cation concentrations by measuring the tunnelling current across films of nanoparticles decorated with striped monolayers of organic ligands.

See also: News and Views by Rurack

Macroporous nanowire nanoelectronic scaffolds for synthetic tissues   pp986 - 994
Bozhi Tian, Jia Liu, Tal Dvir, Lihua Jin, Jonathan H. Tsui, Quan Qing, Zhigang Suo, Robert Langer, Daniel S. Kohane and Charles M. Lieber
doi:10.1038/nmat3404
Three-dimensional bioactive scaffolds can support tissue growth for studies in cellular biophysics and regenerative medicine. Such scaffolds have now been integrated with semiconductor nanowires to probe their porous interior, allowing for real-time monitoring of signals such as the response of neural and cardiac tissue models to drugs.