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New Functionalities in Abundant Element Oxides: Ubiquitous Element Strategy

'Ubiquitous element strategy' for overcoming potential deficiencies of rare elements in the synthesis of industrially important electronic, thermionic, and structural materials

Tsukuba, Japan, July 5, 2011 - (ACN Newswire) - Japanese scientists report on a unique 'ubiquitous element strategy' for synthesizing industrially important electronic, thermionic, and structural materials using naturally abundant elements. This strategy aims to overcome the 'rare-element crisis'that was triggered by increasing demand for such elements as lithium, used in batteries, and dysprosium for Ne-Fe-B permanent magnets.

In the review article published in the journal Science and Technology of Advanced Materials [ http://dx.doi.org/10.1088/1468-6996/12/3/034303 ] scientists from Tokyo Institute of Technology describe their research on the synthesis and applications of oxide materials based on the 2030 most abundant elements including Si, Al, Ca, Na, and Mg. The key to this strategy is an in-depth knowledge of the role of elements in the physical properties of materialsknowledge available from research on the science and technology of nanometer-sized materials.

Research covered in this paper includes:

The conversion of ceramic 12CaOz7Al2O3 (C12A7)interconnected, positively charged nano-cagesinto a chemically and thermally stable transparent conductor which undergoes a metal-superconductor transition at 0.2 K. C12A7 has a wide bandgap of >7 eV and a low work function of 2.4 eV. The authors describe the synthesis, properties, and applicationslight-emitting, electron field emitters, and nonvolatile memoriesof C12A7 based on their own research.

The generation of ionized oxygen is important in the electronicsindustry for applications including the production of silicon diode layers on semiconductors. Conventional methods rely on the catalytic action of Pta metal in scarce supply. Here, the researchers describe the production of large quantities of atomicoxygen by incandescent heating of 2-mm-diameter tube of yttria-doped zirconiaa solid oxide electrolyte that conducts oxygen ions. This method of generating atomic oxygen is more efficient, highly selective in the types of ions generated, and enableslower temperature oxidation of silicon compared with thermal oxidation.

In another example of the 'ubiquitous element strategy' the authors describe the effect of phase transitions on the controlled fracture in mullite ceramics (3Al2O32SiO2), which is crucial for impact-resistant armor and bumper shields for spacecraft. The researchers found that mullite exhibited superior protection as Whipple bumper shields compared to conventional aluminum alloys "tested for the impact by an aluminum alloy flyer at 5.5 km/s".

Other materials discussed include SrTiO3/TiO2, exhibiting a fivefold higher Seebeck effect compared with bulk material; the pulsed laser deposition of flat MgO(111) films on Al2O3(0001) substrates and of atomically flat MgO(111) films on YSZ(111) substrates with NiO(111) buffer layers.

This up to date and highly informative review includes 34 figures and 115 references.

Related information

[1] Hideo Hosono(1),(2),(3), Katsuro Hayashi(2), Toshio Kamiya(2),(3),Toshiyuki Atou(2) and Tomofumi Susaki(2),(4), "New functionalities in abundant element oxides: ubiquitous element strategy",
Science and Technology of Advanced Materials 12 (2011) p. 034303.
[ http://dx.doi.org/10.1088/1468-6996/12/3/034303 ]
(1)Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
(2) Secure Materials Center, Materials and Structures Laboratory, Tokyo Institute of Technology, Nagatsuta, Midori, Yokohama 226-8503, Japan
(3) Materials and Structures Laboratory, Tokyo Institute of Technology, Nagatsuta, Midori, Yokohama 226-8503, Japan
(4) Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan

Press document:
http://iopscience.iop.org/1468-6996/12/3/034303/pdf/1468-6996_12_3_034303.pdf

Media contacts:
Mikiko Tanifuji
National Institute for Materials Science,
Tsukuba, Japan
Email: stam_office@nims.go.jp
Tel. +81-(0)29-859-2494

Source: National Institute for Materials Science