Structure of a new high-pressure–high-temperature modification of antimony(III) oxide, γ-Sb₂O₃, from high-resolution synchrotron powder diffraction data

A quenchable new high-pressure–high-temperature modification of antimony(III) oxide, γ-Sb₂O₃, has been obtained at hydrostatic pressures of 9–11 GPa and temperatures of 573–773 K. Its crystal structure has been determined from high-resolution synchrotron powder diffraction data. γ-Sb₂O₃ consists of three-dimensionally cross-linked infinite chains of SbO₃E units (E = lone pair) with the chains forming tetragonal rod-packing. The underlying topology of γ-Sb₂O₃ (3,3T8) is found very rarely in inorganic structures; it is realised only for the polyanion [Si₄O₄N₆]¹⁰⁻ that occurs in the Ce₄(Si₄O₄N₆)O structure type. The structural relation to the two previously known polymorphs of Sb₂O₃ at ambient pressure, valentinite and senarmontite is discussed.

Computing details

Cell refinement: TOPAS v4.1, Bruker-AXS, 2007; program(s) used to solve structure: Endeavour v1.4, Cyrstal-Impact, 2000-2006; program(s) used to refine structure: TOPAS v4.1, Bruker-AXS, 2007; molecular graphics: Diamond v3.1, Crystal Impact, 2011.

Antimony (III) trioxide

Crystal data

O3Sb2	c = 7.4771 Å
Mr = 291.50	V = 658.6 Å^3
Orthorhombic, P212121	Z = 8
Hall symbol: P_2ac_2ab	Synchrotron radiation
a = 11.6411 (1) Å	T = 298 K
b = 7.5666 Å

Data collection

Multianalyser stage diffractometer	Si(111) monochromator
Radiation source: ESRF ID31	2θmin = 1.0°, 2θmax = 25.84°, 2θstep = 0.002°

Refinement

Rp = 0.043	Rexp = 0.021
Rwp = 0.067	82 parameters

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Sb1	0.2342 (2)	0.4688 (2)	0.4711 (3)	0.5 (1)
Sb2	0.5116 (2)	0.1844 (2)	0.2784 (2)	0.7 (1)
Sb3	0.0050 (2)	0.2450 (2)	0.2421 (3)	0.7 (1)
Sb4	0.2382 (2)	0.0095 (3)	0.0142 (3)	0.7 (1)
O1	0.4097 (14)	0.4768 (19)	0.162 (2)	0.2 (3)
O2	0.1540 (14)	0.403 (2)	0.263 (2)	1.4 (4)
O3	0.1029 (14)	0.0264 (18)	0.1951 (19)	0.1 (3)
O4	0.0043 (18)	0.1803 (15)	0.5063 (19)	1.5 (3)
O5	0.2481 (16)	0.2408 (19)	0.6186 (19)	1.1 (4)
O6	0.3596 (16)	0.0479 (19)	0.301 (3)	1.4 (4)