Recently a new progress on metallic Boron Nitride (BN) has been made by Prof. Qian Wang’s group at the Center for Applied Physics and Technology (CAPT), College of Engineering at Peking University and her collaborators. With the aid of state-of-the-art theoretical calculations, they proposed new BN allotropes which exhibit unusual metallicity. This work is recently published in Journal of the American Chemical Society (J. Am. Chem. Soc.2013, 135, 18216？18221).
How to convert an insulator or semiconductor into a metal is an important and fundamental topic. Much of the current electronics depend upon this. For nearly a century this is primarily accomplished by doping. Manipulating their structure to induce a metallic transition, however, has not been a common practice. It is in this aspect that Wang and co-workers focused on BN which is a chemical analogue of Carbon and shares with it similar structures such as one-dimensional nanotube, two-dimensional nanosheet characterized by sp2 bonding, and three-dimensional (3D) diamond structure characterized by sp3 bonding. However, unlike Carbon which can be metallic in certain forms, BN is an insulator, irrespective of its structure and dimensionality. Taking the advantage of boron’s capacity to form multielectron-multicenter bonds, Wang and co-workers designed the tetragonal structures of BN containing both sp2 and sp3 hybridizations based on first-principle density-functional calculations. The new phases of BN are both dynamically stable and metallic. Analysis of their electronic structures reveals the metallic behavior comes from the delocalized B 2p electrons. The metallicity exhibited in the studied 3D BN structures can lead to materials beyond conventional ceramics as well as to materials with novel transport properties and potential for applications in electronic devices. High-temperature insulator has metallic potential. This work may stimulate experimentalists to synthesize these novel forms of metallic BN and once that is achieved, it will have transformative impact on science and technology.
This work has been highlighted by “Spotlights on Recent JACS Publications” and Chemistryviews:
No comments:
Post a Comment