8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P1.22Fri 911:10-14:00Network of tetrahedral Hg 4 blocks in expanded liquid HgKenji Maruyama, 1 Hirohisa Endo, 2 Hideoki Hoshino, 3 Friedrich Hensel, 4 andTakashi Odagaki 51 Niigata Univ., 8050 Igrashi-2, 950-2181, Niigata, Japan2 Kyoto Univ., Kyoto, Japan3 Hirosaki Univ., Hirosaki, Japan4 Philipps-Universität Marburg, Marburg, Germany5 Tokyo Denki Univ., Hatoyama-Cho, JapanRecent work [1] using the reverse Monte Carlo (RMC) and Voronoi-Delaunay (V-D) analyseshas shown that the structure of expanded liquid Hg can be envisaged in terms of a packing ofsmall voids (S-voids) ∼2.3Å in radius corresponding to the empty space inside of tetrahedral Hg 4blocks and large voids (L-voids) ∼3.1Å in radius supported by the network of tetrahedral Hg 4blocks created in the stage of volume expansion. In the present work the network connectivities oftetrahedral Hg 4 blocks near the metal-nonmetal (M-NM) transition are discussed. We define themetallic domains (M domains) embedded in the nonmetallic domains (NM domains) as consistingof the face- or edge-sharing (F-S, E-S) tetrahedron-based ”clusters” with the number of coordinatedtetrahedra N ≥ 3 at the separation of neighboring tetrahedra, RS = 1.3 - 2.5Å . The numberfraction for M domains estimated from RMC configurations decreases rapidly as the density islowered, correspondingly that for NM domains increases. The ring- or chain-network linked bycorner-sharing (C-S) tetrahedra with N ≤ 9 at the separation RS = 7.2 - 7.5Å corresponding tothe medium-ranged correlation length between tetrahedra on the ring or chain across the L-voidwhich gives a basic structural unit of NM domains, develops near the M-NM transition. Thefindings reveal that ∼9 L-voids are captured around the L-void indicative of chemical orderingof L-voids (microsegregation of NM domains). It is noteworthy that the volume fraction of Mdomains comes to ∼0.2 at the density of 9 gcm −3 near the transition. Assuming that the transitioncould be characterized as a percolation transition in the network of M domains [2], the relativelyhigh threshold fraction may be correlated with long-lived concentration fluctuations of M and NMdomains to support a stable percolation channel.[1] K. Maruyama, et al. , PRB 80, 014201 (2009)[2] W. Ruland, et al. , J. Appl. Cryst. 43, 244 (2010)22