Inorganic Materials, Vol. 40, No. 10, 2004, pp. 1095–1096. Translated from Neorganicheskie Materialy, Vol. 40, No. 10, 2004, pp. 1247–1248.
Original Russian Text Copyright © 2004 by Gasymov, Gasymova, Aliev.
Synthesis and X-ray Diffraction Characterization
of FeNdSbS4, an Analog of Berthierite
V. A. Gasymov*, G. N. Gasymova**, and O. M. Aliev*
* Institute of Chemical Problems, Academy of Sciences of Azerbaijan,
pr. Javida, 29, Baku, AZ1143 Azerbaijan
** Tusi State Pedagogical University, ul. Gajibekova 34, Baku, AZ1060 Azerbaijan
e-mail: v-gasymov@rambler.ru
Received November 12, 2003; in final form, May 14, 2004
Abstract—A rare-earth-containing analog of the mineral berthierite, with the composition FeNdSbS4, was
synthesized for the first time. FeNdSbS4 is isostructural with FeSb2S4 and crystallizes in orthorhombic symme-
try (sp. gr. Pbam, Z = 4) with lattice parameters a = 11.395 Å, b = 14.136 Å, and c = 3.747 Å.
The crystal-chemical prediction and synthesis of
new compounds with a particular structure is of major
practical importance. The preparation of analogs of
some minerals, in particular berthierite, FeSb2S4, is of
special interest since it allows one to extend the range
of known multicomponent compounds [1].
FeNdSbS4 was synthesized by the sealed-ampule
technique from stoichiometric mixtures of NM-O
neodymium (99.7+% Ln), carbonyl iron, Su-O anti-
mony (99.999%), and V4 sulfur (99.9999%).
The mixtures (4–5 g) were sealed in silica tubes
pumped down to 0.13 Pa and loaded into an electric fur-
nace preheated to 750 K. At this temperature, the reac-
tion, stirred by rotating the tube, took 1 h to reach com-
pletion. The furnace was then brought to a vertical posi-
tion, and the samples were heated to 1250 K and held
there for 1 h. Next, the temperature was lowered to
870 K at a rate of 50 K/h, and the samples were homog-
enized by annealing at this temperature.
FeSb2S4 occurs in nature as the mineral berthierite
and crystallizes in orthorhombic symmetry [2]. In the
structure of berthierite, Sb is in fivefold coordination
and sits in two positions 4c of the space group Pbam.
The Sb(1) atom (figure) resides off the base of the
hemioctahedron and is slightly displaced toward the
center of the adjacent “vertical” trigonal prism. In addi-
tion, the vertical trigonal prism shares faces with two
empty hemioctahedra. The Sb(2) atom at z = 3/4 lies in
the base of a hemioctahedron, which shares this face
with a “horizontal” trigonal prism. In addition, the hor-
izontal trigonal prism shares one of its rectangular faces
with a hemioctahedron occupied by Sb(2) at z = 1/4. It
is easily seen that a further displacement of Sb(1)
toward the center position of the vertical trigonal prism
may increase the coordination number (CN) of Sb(1)
up to nine. The unit cell of FeSb2S4 contains four struc-
tural units displayed in the figure (not including the
hemioctahedron shown by dashed lines).
The annealing temperature and duration were cho-
sen on the basis of x-ray diffraction (XRD) and micro-
structural examination results: annealing for 15 days
yielded dark gray needle-like crystals of stoichiometric
composition.
Sb(2)
As is known, lanthanides in mixed sulfides may be
in octahedral, trigonal prismatic, and mono-, bi-, and
tricapped trigonal prismatic coordination (CN = 6 to 9).
This suggests that Sb(1) in FeSb2S4 can be partially
substituted by rare-earth elements to give new com-
pounds.
Sb(1)
z
S
1/4
Fe
3/4
The purpose of this work was to prepare a rare-
earth-containing analog of berthierite via partial neody-
mium substitution for antimony in hemioctahedra.
Structural unit of berthierite, FeSb S .
2
4
0020-1685/04/4010-1095 © 2004 MAIK “Nauka/Interperiodica”
Gasymov
