TY - JOUR

T1 - Hydrostatic compression of galenobismutite (PbBi2S4)

T2 - elastic properties and high-pressure crystal chemistry

AU - Olsen, Lars Arnskov

AU - Balic Zunic, Tonci

AU - Makovicky, Emil

AU - Ullrich, Angela

AU - Miletich, Ronald

PY - 2007

Y1 - 2007

N2 - A single-crystal sample of galenobismutite was subjected to hydrostatic pressures in the range of 0.0001 and 9 GPa at room temperature using the diamond-anvil cell technique. A series of X-ray diVraction intensities were collected at ten distinct pressures using a CCD equipped 4-circle diVractometer. The crystal structure was reWned to R1(|F0| > 4s) values of approximately 0.05 at all pressures. By Wtting a third-order Birch-Murnaghan equation of state to the unit-cell volumes V0 = 700.6(2) Å3, K0 = 43.9(7) GPa and dK/dP = 6.9(3) could be determined for the lattice compression. Both types of cations in galenobismutite have stereochemically active lone electron pairs, which distort the cation polyhedra at room pressure. The cation eccentricities decrease at higher pressure but are still pronounced at 9 GPa. Galenobismutite is isotypic with CaFe2O4 (CF) but moves away from the idealised CF-type structure during compression. Instead of the two octahedral cation sites and one bi-capped trigonal-prismatic site, PbBi2S4 attains a new high-pressure structure characterised by one octahedral site and two mono-capped trigonal-prismatic sites. Analyses of the crystal structure at high pressure conWrm the preference of Bi for the octahedral site and the smaller one of the two trigonal-prismatic sites.

AB - A single-crystal sample of galenobismutite was subjected to hydrostatic pressures in the range of 0.0001 and 9 GPa at room temperature using the diamond-anvil cell technique. A series of X-ray diVraction intensities were collected at ten distinct pressures using a CCD equipped 4-circle diVractometer. The crystal structure was reWned to R1(|F0| > 4s) values of approximately 0.05 at all pressures. By Wtting a third-order Birch-Murnaghan equation of state to the unit-cell volumes V0 = 700.6(2) Å3, K0 = 43.9(7) GPa and dK/dP = 6.9(3) could be determined for the lattice compression. Both types of cations in galenobismutite have stereochemically active lone electron pairs, which distort the cation polyhedra at room pressure. The cation eccentricities decrease at higher pressure but are still pronounced at 9 GPa. Galenobismutite is isotypic with CaFe2O4 (CF) but moves away from the idealised CF-type structure during compression. Instead of the two octahedral cation sites and one bi-capped trigonal-prismatic site, PbBi2S4 attains a new high-pressure structure characterised by one octahedral site and two mono-capped trigonal-prismatic sites. Analyses of the crystal structure at high pressure conWrm the preference of Bi for the octahedral site and the smaller one of the two trigonal-prismatic sites.

KW - Faculty of Science

KW - Lone electron pair

KW - High pressure

KW - Galenobismutite

KW - Equation of state

KW - Calcium ferrite structuretype

U2 - 10.1007/s00269-007-0163-9

DO - 10.1007/s00269-007-0163-9

M3 - Journal article

VL - 34

SP - 467

EP - 475

JO - Physics and Chemistry of Minerals

JF - Physics and Chemistry of Minerals

SN - 0342-1791

IS - 7

ER -