Paper SS-TuP21
Comparative Study of the Electronic Structure of ZrB₂ and ZrB₁₂

Tuesday, October 16, 2007, 6:00 pm, Room 4C

X-ray photoemission spectroscopy (XPS) and Ultraviolet photoemission spectroscopy (UPS) are used to compare the electronic structures of ZrB₂ and ZrB₁₂. The Zr 3d and B 1s core levels associated with the chemical states of ZrB₂ and ZrB₁₂ were identified, the Zr 3d core level shows a spin-orbit split 3d_5/2 and 3d_3/2 while that the B 1s core levels exhibit a single asymmetric peak typical of a metallic boride. Comparing with Zr metallic, boron and ZrO₂ reference materials, for ZrB₂ we observed a positive chemical shift for B 1s and a negative chemical shift for Zr 3d_3/2 while that in ZrB₁₂ the chemical shift in B 1s and Zr 3d_3/2 is inverse, suggesting that a some charge transfer occurred from the Zr atoms to the B atoms in the ZrB₂ and from the B atoms to the Zr atoms in ZrB₁₂. The measured valence bands using UPS and XPS are consistent with band-structure calculations indicating a higher density of states (DOS) at E_F for ZrB₁₂ compared to ZrB₂. That’s suggesting that the T_c in ZrB₁₂ is due to B 2p and Zr 4d-derived DOS at E_F.