THE ROLE OF THE Sb3+ LONE-ELECTRON PAIRS AND Fe2+ COORDINATION IN THE HIGH-PRESSURE BEHAVIOR OF BERTHIERITE

摘要: A single crystal of natural berthierite, FeSb 2 S 4 , was investigated at high pressure by means X-ray diffraction using a diamond-anvil cell equipped with diamond backing plates. No phase transitions were indicated up to 8 GPa. The third-order Birch–Murnaghan equation state, calculated high-accuracy volume–pressure data 8.05 GPa, gave the following coefficients: V 0 = 608.78(7) 3 K T0 37.2(2) GPa and ′ 7.0(1). evolution structure as function has been determined seven different pressures 7.41 As in other structures stereochemically active lone-electron pairs (LEP), Sb 3+ LEP, influencing long Sb–S bonds accommodate most compression. Fe octahedron, which is stiffest coordination polyhedron increases its distortion until approximately 5 but shows pronounced stiffening higher pressures. This deformation can be related an increase Jahn–Teller effect on 2+ coordination. influence compressional behavior makes distinct difference between compression berthierite that stibnite, . bridging structural rods it stiffer. This, together direct relation analogous PbBi galenobismutite, characteristics more akin those despite quantitative differences stereochemical expression LEP Bi