Download citation
Download citation
link to html
The structure of pyrrhotite (Fe1 − xS with 0.05 ≤ x ≤ 0.125) has been reinvestigated in the framework of the superspace formalism. A common model with a centrosymmetric superspace group is proposed for the whole family. The atomic domains in the internal space representing the Fe atoms are parametrized as crenel functions that fulfil the closeness condition. The proposed model explains the x-dependent space groups observed and the basic features of the structures reported up to now. Our model yields for any x value a well defined ordered distribution of Fe vacancies in contrast to some of the structural models proposed in the literature. A new (3 + 1)-dimensional refinement of Fe0.91S using the deposited dataset [Yamamoto & Nakazawa (1982). Acta Cryst. A38, 79–86] has been performed as a benchmark of the model. The consistency of the proposed superspace symmetry and its validity for other compositions has been further checked by means of ab initio calculations of both atomic forces and equilibrium atomic positions in non-relaxed and relaxed structures, respectively.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks global, I


Structure factor file (CIF format)
Supplementary material

Computing details top

Program(s) used to refine structure: (Jana2000; Petricek and Dusek, 2000); software used to prepare material for publication: (Jana2000; Petricek and Dusek, 2000).

(I) top
Crystal data top
Fe0.91SV = 473.15 (11) Å3
Mr = 82.9Z = 16
Orthorhombic, (000???†F(000) = 1269
q = 0.18050c*Dx = 4.652 Mg m3
a = 6.892 (1) ÅMo Kα radiation, λ = 0.71069 Å
b = 11.952 (1) ŵ = 12.54 mm1
c = 5.744 (1) ÅT = 293 K
† Symmetry operations: (1) x1, x2, x3, x4; (2) 1/4+x1, −x2, 1/2+x3, 1/4+x4; (3) x1, 1/4−x2, −x3, 1/4−x4; (4) 1/4+x1, 1/4+x2, 1/2−x3, −x4; (5) −x1, −x2, −x3, −x4; (6) 1/4−x1, x2, 1/2−x3, 1/4−x4; (7) −x1, 1/4+x2, x3, 1/4+x4; (8) 1/4−x1, 1/4−x2, 1/2+x3, x4; (9) 1/2+x1, 1/2+x2, x3, x4; (10) 3/4+x1, 1/2−x2, 1/2+x3, 1/4+x4; (11) 1/2+x1, 3/4−x2, −x3, 1/4−x4; (12) 3/4+x1, 3/4+x2, 1/2−x3, −x4; (13) 1/2−x1, 1/2−x2, −x3, −x4; (14) 3/4−x1, 1/2+x2, 1/2−x3, 1/4−x4; (15) 1/2−x1, 3/4+x2, x3, 1/4+x4; (16) 3/4−x1, 3/4−x2, 1/2+x3, x4; (17) x1, 1/2+x2, x3, 1/2+x4; (18) 1/4+x1, 1/2−x2, 1/2+x3, 3/4+x4; (19) x1, 3/4−x2, −x3, 3/4−x4; (20) 1/4+x1, 3/4+x2, 1/2−x3, 1/2−x4; (21) −x1, 1/2−x2, −x3, 1/2−x4; (22) 1/4−x1, 1/2+x2, 1/2−x3, 3/4−x4; (23) −x1, 3/4+x2, x3, 3/4+x4; (24) 1/4−x1, 3/4−x2, 1/2+x3, 1/2+x4; (25) 1/2+x1, x2, x3, 1/2+x4; (26) 3/4+x1, −x2, 1/2+x3, 3/4+x4; (27) 1/2+x1, 1/4−x2, −x3, 3/4−x4; (28) 3/4+x1, 1/4+x2, 1/2−x3, 1/2−x4; (29) 1/2−x1, −x2, −x3, 1/2−x4; (30) 3/4−x1, x2, 1/2−x3, 3/4−x4; (31) 1/2−x1, 1/4+x2, x3, 3/4+x4; (32) 3/4−x1, 1/4−x2, 1/2+x3, 1/2+x4.

Data collection top
605 measured reflectionsθmax = 26.0°, θmin = 2.6°
588 independent reflectionsh = 05
391 reflections with I > 3σ(I)k = 014
Rint = 0.786l = 40
Refinement top
Refinement on F588 reflections
R[F2 > 2σ(F2)] = 0.11546 parameters
wR(F2) = 0.096Unit
S = 4.81(Δ/σ)max = 0.017
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
Fe10.1264 (4)0.12500.0120 (10)
S10.1250.0426 (2)0.750.0073 (9)*
Atomic displacement parameters (Å2) top
Fe10.0102 (19)0.0160 (11)0.0098 (19)000.0002 (10)

Follow Acta Cryst. B
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds