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Recently a group of scientists from Bayerisches Geoinstitut (Natalia Dubrovinskaia and Leonid Dubrovinsky) and Université Paris Nord (Vladimir Solozhenko ) succeeded in synthesis of a new composite superhard material, which consists of intergrown boron carbide B4C and heavily B-doped diamond (with 1.8 at% B).
Bayreuth (UBT). Due to combination of unique physical and chemical properties such as hardness, high thermal conductivity, wide band gap, high electron and hole mobility, chemical inertness, diamond found wide applications in modern science and technology. There is growing demand in diamond-like materials in electronic applications. Although there are little prospects of diamond-based microelectronics ousting silicon totally, diamond devices could function in situations when silicon electronics fails. For example, diamond chips potentially could still work at temperatures of several hundred degrees, whereas silicon devices generally fail above 450 K. Electrochemical applications of diamond-based films have been developed significantly in the last few years and are considered as a promising research area. Pure diamond is a perfect insulator and conducts electricity very poorly. But, like silicon, it can be turned into a semiconductor by traces of boron or nitrogen impurities.
Recently a group of scientists from Bayerisches Geoinstitut (Natalia Dubrovinskaia and Leonid Dubrovinsky) and Université Paris Nord (Vladimir Solozhenko ) succeeded in synthesis of a new composite superhard material, which consists of intergrown boron carbide B4C and heavily B-doped diamond (with 1.8 at% B). For the synthesis they used a unique 5000-tonn multianvil press operated at BGI. The results were published in Applied Physics Letters (Ref. 1).
Synthesis of new classes of hard and superhard materials provide new challenges for the measurement of hardness. N. Dubrovinskaia contributed to the development of methodology of the measurement of hardness of superhard materials summarized and just published in Nature Materials (Ref. 2). The hardness measurements of the new composite B-C material, carried out according to the newly developed methodology, have shown that the new material exhibits extreme hardness (88 GPa) comparable with that of single-crystal diamond. Synthesis of composite ceramics with hardness approaching that of diamond suggests that new superhard materials could be not only among monophases that opens new perspectives for synthesis of materials with unique properties. Moreover, combination of semiconducting properties and extreme hardness makes the synthesised material potentially very important for precision machining and electronic (high-power, high-frequency) applications due to it can be easily processed (polished and shaped) using electrochemical methods (Fig. 1).
References
Ref. 1. V. Solozhenko, N.A. Dubrovinskaia, L.S. Dubrovinsky. Synthesis of bulk superhard semiconducting B-C material. Applied Physics Letters, 2004, 85, 9, 1508- 1510.
Ref. 2. V. Brazhkin, N. Dubrovinskaia, M. Nicol, N. Novikov, R. Riedel, V. Solozhenko, and Y. Zhao. What does "Harder than Diamond" mean? Nature Materials, 2004, 3, 576- 577.
Fig. 1
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Natalia Dubrovinskaia and Leonid Dubrovinsky
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Fig. 1
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Natalia Dubrovinskaia and Leonid Dubrovinsky
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