Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan.
J Am Chem Soc. 2012 Feb 8;134(5):2516-9. doi: 10.1021/ja211293x. Epub 2012 Jan 24.
Various layered boronitrides (LaN)(n)(T(M2)B(2)) (T(M) = transition metal; n = 2, 3) have been prepared using a high-pressure synthesis technique in which an inverse α-PbO-type T(M2)B(2) layer is separated by two or three rock salt-type LaN layers and these layers are connected through linear (BN) units. The electronic states of the distinguishing (BN) unit and intermediate rock salt-type LaN layer are discussed on the basis of density functional theory calculations. Bulk superconductivity has been found in LaNiBN (T(c) ≈ 4.1 K), CaNiBN (T(c) ≈ 2.2 K), and LaPtBN (T(c) ≈ 6.7 K), where the Fermi level E(F) is located in the bands composed of the T(M)(d)-B(2p) antibonding state and the main T(M)(d) band resides well below E(F). The non-superconductive T(M)-based compounds exhibit Pauli paramagnetic behavior, in which the highly itinerant nature of the electrons caused by strong T(M)(d)-B(2p) covalent bonding suppresses the long-range magnetic ordering.
各种层状硼氮化物 (LaN)(n)(T(M2)B(2)) (T(M) = 过渡金属; n = 2, 3) 已通过高压合成技术制备，其中反α-PbO 型 T(M2)B(2)层被两个或三个岩盐型 LaN 层隔开，这些层通过线性 (BN) 单元连接。基于密度泛函理论计算，讨论了区分 (BN) 单元和中间岩盐型 LaN 层的电子态。在 LaNiBN（T(c) ≈ 4.1 K）、CaNiBN（T(c) ≈ 2.2 K）和 LaPtBN（T(c) ≈ 6.7 K）中发现了体超导性，其中费米能级 E(F) 位于由 T(M)(d)-B(2p)反键态组成的能带中，并且主要 T(M)(d) 带位于 E(F) 以下。非超导性的 T(M)基化合物表现出 Pauli 顺磁行为，其中由强 T(M)(d)-B(2p) 共价键引起的电子的高度离域性质抑制了长程磁有序。
