AVS 51st International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoP

Paper EM-MoP11
Future Super Conducting MeB@sub 2@ Materials

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: I. Arvidssson, Uppsala University, Sweden
Authors: I. Arvidssson, Uppsala University, Sweden
A. Pallas, Uppsala University, Sweden
K. Larsson, Uppsala University, Sweden
Correspondent: Click to Email
Metal diborides (MeB@sub 2@) often have interesting thermal, mechanic and superconducting properties. MgB@sub 2@ was put into focus some years ago for its high transition temperature (39 K) in combination with its simple AlB@sub 2@-structure. The boron structure in MeB@sub 2@, with interesting similarities to graphite structures, is much dependent of the electron transfer from the nearby metal atoms. An electronic and structural comparison has here been performed for various planar and puckered transition metal borides using quantum mechanical calculations. In comparison to MgB@sub 2@ the transition metal diborides MoB@sub 2@, ZrB@sub 2@, RuB@sub 2@, and PdB@sub 2@ have been examined. The first two are planar with AlB@sub 2@ structure and the latter two have in experiments been shown to have a structure similar to puckered CaSi@sub 2@. The theoretical method used in the calculations is the density functional theory (DFT). Calculations were performed for each of the metal diborides as both planar AlB@sub 2@-structures and as puckered CaSi@sub 2@-structure. Extensive test calculations have been performed to ensure the accuracy of the model template and the calculation parameters. The results indicate that there are differences in stability for the planar and puckered structures. This variance in thermal stability was found to strongly correlate to differences in electron transfer between the metal atom and the boron skeleton.