Difference in the outermost layer betweenTaB2(0001)andHfB

Abstract

Atomic and electronic structures of TaB 2 (0001) and HfB 2 (0001) surfaces are investigated with use of the first-principles pseudopotential calculations. Our calculated surface formation energies indicate that the graphitic-boron-terminated TaB 2 (0001) surface is energetically more favorable, whereas the HfB 2 (0001) surface prefers termination with a close-packed Hf layer. These findings are consistent with experimental facts. We have also found the difference in the surface relaxation between them. The first interlayer spacing of the B-terminated TaB 2 surface is expanded by 0.39%. On the other hand, the outermost Hf-terminated HfB 2 surface is contracted by 4.8%.

Electronic States of NbB2(0001), TaB2(0001) and ZrB2(0001) Surfaces Studied by Angle-resolved Ultraviolet Photoelectron Spectroscopy

“…The binding energies of the B-σ bonds of ZrB 2 (0001) is about 1 eV lower than those of NbB 2 (0001) and TaB 2 (0001), which are related with the difference of the E F level. The surface electronic structures of MB 2 (0001) observed in this work were consistent with the surface structures determined experimentally, and the theoretical results by Yamamoto et al [4].…”

“…The surface properties have been widely investigated experimentally and theoretically [4][5][6][7]. The surfaces of ZrB 2 (0001) and HfB 2 (0001) are terminated with the metal layer [8,9], and the surfaces of NbB 2 (0001) and TaB 2 (0001) are terminated with the B layer [8,10].…”

“…Here, M IV and M V mean the metal atoms of group IV and group V in the periodic table, respectively. In previous work, Yamamoto et al indicated theoretically that the surface termination is closely related to the amount of valence electrons of the metal atom [4]. While the electronic structure of TaB 2 (0001) surface has been * This paper was presented at International Symposium on Surface Science and Nanotechnology (ISSS-4), Saitama, Japan, 14-17 November, 2005.…”

Interactions of water molecule with HfB2 and TaB2 (0001) surfaces: A first-principles investigation

“…Some experiments and theoretical calculations have demonstrated that the terminated (0 0 0 1) surfaces of HfB 2 and TaB 2 are different [14][15][16]. For HfB 2 , the Hf-terminated (0 0 0 1) surface is more favorable than B-terminated surface, while B-terminated surface is favorable for TaB 2 .…”

“…Among the surfaces of HfB 2 and TaB 2 crystals, the (0 0 0 1) surfaces have been the most studied to date. However, the Hf-terminated (0 0 0 1) surface of HfB 2 is different from the B-terminated (0 0 0 1) surface of TaB 2 [14]. The (0 0 0 1) surfaces exhibit different chemical reactivity.…”