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Title: Ni{sub 7-{delta}}SnTe{sub 2}: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity

Abstract

Single crystals of Ni{sub 7-{delta}}SnTe{sub 2} were grown during re-crystallization of the presynthesized powder in a two zone furnace. The modulated structure was solved and refined in the (3+2)-dimensional superspace group I4/mmm(0-{alpha}0, {alpha}00)0.ss.mm with lattice parameters a=3.759(1) and c=19.410(2)A (measured at 153K) and Z=2. Satellite reflections observed in the diffraction images can be assigned to the incommensurate modulation vectors q{sub 1}=da* and q{sub 2}=db* with d=0.410(1). The composition resulting from X-ray structure refinement is Ni{sub 5.81}SnTe{sub 2}. The structure model has been also developed in the orthorhombic (3+1)-dimensional superspace group Immm({alpha}00)00s assuming twinning according to [110], giving thus the composition Ni{sub 5.79}SnTe{sub 2}. The origin of the modulation can be attributed to a variation of the occupancy of the Ni(3) site in Ni/Te slabs of the structure. Band structure calculations on a commensurate approximant and single crystal electrical resistivity measurements reveal anisotropic metallic conductivity for this compound.

Authors:
 [1];  [2];  [3];  [4];  [5];  [5];  [5];  [6]
  1. Department of Materials Science, Moscow State University, Leninskie Gory, Moscow 119992, GSP-2 (Russian Federation)
  2. Max Planck Institute for Chemical Physics of Solids, Noethnitzer Strasse, 40, 01187 Dresden (Germany)
  3. Institute of Inorganic Chemistry, Dresden University of Technology, 01062 Dresden (Germany)
  4. Department of Chemistry, Moscow State University, Leninskie Gory, Moscow 119992, GSP-2 (Russian Federation), E-mail: popovkin@inorg.chem.msu.ru
  5. Department of Physics, Moscow State University, Leninskie Gory, Moscow 119992, GSP-2 (Russian Federation)
  6. Department of Chemistry, Moscow State University, Leninskie Gory, Moscow 119992, GSP-2 (Russian Federation)
Publication Date:
OSTI Identifier:
21015641
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 1; Other Information: DOI: 10.1016/j.jssc.2006.09.003; PII: S0022-4596(06)00505-6; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANISOTROPY; CHALCOGENIDES; CHEMICAL BONDS; CRYSTALLIZATION; DIFFRACTION; ELECTRIC CONDUCTIVITY; ELECTRONIC STRUCTURE; LATTICE PARAMETERS; MONOCRYSTALS; ORTHORHOMBIC LATTICES; POWDERS; TETRAGONAL LATTICES; TWINNING

Citation Formats

Isaeva, A.A., Baranov, A.I., Doert, Th., Popovkin, B.A., Kulbachinskii, V.A., Gurin, P.V., Kytin, V.G., and Shtanov, V.I.. Ni{sub 7-{delta}}SnTe{sub 2}: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.09.003.
Isaeva, A.A., Baranov, A.I., Doert, Th., Popovkin, B.A., Kulbachinskii, V.A., Gurin, P.V., Kytin, V.G., & Shtanov, V.I.. Ni{sub 7-{delta}}SnTe{sub 2}: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity. United States. doi:10.1016/j.jssc.2006.09.003.
Isaeva, A.A., Baranov, A.I., Doert, Th., Popovkin, B.A., Kulbachinskii, V.A., Gurin, P.V., Kytin, V.G., and Shtanov, V.I.. Mon . "Ni{sub 7-{delta}}SnTe{sub 2}: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity". United States. doi:10.1016/j.jssc.2006.09.003.
@article{osti_21015641,
title = {Ni{sub 7-{delta}}SnTe{sub 2}: Modulated crystal structure refinement, electronic structure and anisotropy of electroconductivity},
author = {Isaeva, A.A. and Baranov, A.I. and Doert, Th. and Popovkin, B.A. and Kulbachinskii, V.A. and Gurin, P.V. and Kytin, V.G. and Shtanov, V.I.},
abstractNote = {Single crystals of Ni{sub 7-{delta}}SnTe{sub 2} were grown during re-crystallization of the presynthesized powder in a two zone furnace. The modulated structure was solved and refined in the (3+2)-dimensional superspace group I4/mmm(0-{alpha}0, {alpha}00)0.ss.mm with lattice parameters a=3.759(1) and c=19.410(2)A (measured at 153K) and Z=2. Satellite reflections observed in the diffraction images can be assigned to the incommensurate modulation vectors q{sub 1}=da* and q{sub 2}=db* with d=0.410(1). The composition resulting from X-ray structure refinement is Ni{sub 5.81}SnTe{sub 2}. The structure model has been also developed in the orthorhombic (3+1)-dimensional superspace group Immm({alpha}00)00s assuming twinning according to [110], giving thus the composition Ni{sub 5.79}SnTe{sub 2}. The origin of the modulation can be attributed to a variation of the occupancy of the Ni(3) site in Ni/Te slabs of the structure. Band structure calculations on a commensurate approximant and single crystal electrical resistivity measurements reveal anisotropic metallic conductivity for this compound.},
doi = {10.1016/j.jssc.2006.09.003},
journal = {Journal of Solid State Chemistry},
number = 1,
volume = 180,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • X-ray single crystal diffraction data were used for structural refinement of the title compounds with different {ital x} (0.15, 0.27, 0.49 and 0.89). Crystals were grown in alumina crucibles using self-flux method. Aluminum, which originates from the crucibles, substitutes only Cu(1), and thus induces tetragonal symmetry which was observed in all four crystals. The main structural effect of praseodymium is an increased separation of superconducting layers. Substituent concentrations ({ital x} and {ital y} in the formula) have been refined and compared with the values obtained by EDX (energy dispersive x-ray analysis) in an electron microscope. It was indicated that themore » refined values of Y:Pr ratio and the oxygen content are more reliable than those obtained by EDX while the refinement is less sensitive for Cu(1):Al ratio and this value is more uncertain. This is in accordance with the result of wet chemical analysis. {copyright} {ital 1996 Materials Research Society.}« less
  • X-ray powder diffraction data of NiAs/Ni{sub 2}In-type Ni{sub 1.60}Sn and Ni{sub 1.63}Sn alloys annealed at or below about 573 K reveal the development of an incommensurately ordered phase called LT''. In this phase Ni(2) atoms occupy partially the trigonal-bipyramidal interstices formed by five Sn within an NiAs-type arrangement Ni(1)Sn. The modulated occupational ordering of Ni(2) in the LT'' phase can be described in the superspace group Cmcm(alpha00)0 s 0, and the parameters describing this occupational modulation were refined together with atomic displacement modulations using the Rietveld method. The structure parameters revealed close structural analogies of the LT'' phase with themore » previously reported commensurate LT-Ni{sub 1+{delta}}Sn and incommensurate LT'-Ni{sub 1+{delta}}Sn phases (A. Leineweber, J. Solid State Chem. 177 (2004) 1197-1212), which both occur for lower Ni contents than the LT'' phase. The 1st-order satellite reflections visible in the powder-diffraction patterns exhibit, with respect to the fundamental reflections, a considerable diffraction-line broadening, caused by a small size of the particularly ordered domains. This small-domain-size broadening was successfully described by a recently developed reflection-index (hklm) dependent (anisotropic) line-broadening model (A. Leineweber, V. Petricek, J. Appl. Crystallogr. 40 (2007) 1027-1034) designed to consider the effect of fluctuations of the lattice metrics on the peak widths in powder diffraction patterns of incommensurately modulated crystal structures. The small domain sizes encountered for the LT'' phase indicate that domain coarsening is much more difficult than for the LT and LT' phases. This special feature of the LT'' phase goes along with a compared to the LT and LT' phases absent orthorhombic distortion and the low ordering temperature, which are discussed as a consequence of the ordering patterns due to the Ni(2) atoms. - Graphical abstract: Approximant structure of incommensurately modulated LT''-Ni{sub 1.60}Sn, forming below 573 K from the disordered phase. The phase has a close structural relationship to the LT and LT' phases occurring at lower Ni contents.« less
  • La{sub 3}Fe{sub 2-{delta}}S{sub 7} (delta=0.042(6)) was synthesized through a reaction of the elements in a LiCl/KCl flux at 970 K, and its structure was determined by single-crystal X-ray diffraction. The compound crystallizes in the polar hexagonal space group P6{sub 3} with a=10.1906(6), c=5.9543(4) A and Z=2, and adopts the Ce{sub 6}Al{sub 10/3}S{sub 14} structure type. The structure contains both octahedral and tetrahedral iron sites: one-dimensional rods of face-sharing FeS{sub 6} octahedra run along the 6{sub 3} screw axis of the cell; FeS{sub 4} tetrahedra, all pointing in the same direction, are stacked along the threefold rotation axes. The iron-centered polyhedramore » are linked by lanthanum atoms, which are coordinated by [7+1] sulfur atoms in a bicapped trigonal prismatic arrangement. {sup 57}Fe Moessbauer spectroscopy confirms that Fe{sup III} and Fe{sup II} cations occupy the tetrahedral and octahedral iron sites, respectively. Magnetic susceptibility data indicate an antiferromagnetic transition at T{sub N}{approx}155 K. Density functional band structure calculations within the local density approximation reveal two covalent Fe-S subsystems within the compound that mix only weakly. A large anisotropy is indicated by bands that disperse predominantly along the hexagonal axis. The electronic band structure suggests pseudo-one-dimensional metallic conductivity along the rods of face-sharing FeS{sub 6} octahedra. However, due to the defects on the Fe{sup II} positions, La{sub 3}Fe{sub 2-{delta}}S{sub 7} shows an activated conducting behavior. - Graphical Abstract: Rods of face-sharing [Fe{sup II}S{sub 6}]-octahedra and [Fe{sup III}S{sub 4}]-tetrahedra, all pointing in the same direction, dominate the polar structure. Vacancies in the octahedral Fe positions downgrade one-dimensional metallic conductivity to an activated semi-conducting behavior.« less
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