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Title: The iron potassium diarsenate KFeAs{sub 2}O{sub 7} structural, electric and magnetic behaviors

Crystals of a new potassium iron (III) diarsenate (KFeAs{sub 2}O{sub 7}) have been grown and characterized by single crystal X-ray diffraction. It crystallizes in the triclinic space group P1-bar, with a=7.662(1) A, b=8.402(2) A, c=10.100(3) A, {alpha}=90.42(3){sup o}, {beta}=89.74(2){sup o}, {gamma}=106.39(2){sup o}, V=623.8(3) A{sup 3} and Z=4. The final agreement factors are R=0.0342, wR=0.0889, S(F{sup 2})=1.01; the structural model is validated by bond valence sum (BVS) and charge distribution (CD) methods. The structure consists of corner-sharing FeO{sub 6} octahedra and As{sub 2}O{sub 7} diarsenate groups, the three-dimensional framework delimits tunnels running along [0 1 0] direction where the potassium ions reside. The crystal structure of the title compound is different from that of the monoclinic KAlP{sub 2}O{sub 7} type but structural relationships exist between the frameworks. Impedance measurements (frequency/temperature ranges: 5-13,000 Hz/526-668 K) show KFeAs{sub 2}O{sub 7} an ionic conductor being the conductivity 2.76x10{sup -7} S cm{sup -1} at 568 K and E{sub a} is 0.47 eV. The BVS model suggests that the most probable potassium conduction pathway is along b-direction. Magnetic measurements reveal the Curie-Weiss type paramagnetic behavior over the range 30-300 K and ferromagnetic below 29.3 K. - Graphical abstract: Optimized trajectory for K1-K2-K1 jump as determined bymore » BVS analysis.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ; ;  [1]
  1. Laboratoire de Materiaux et Cristallochimie, Faculte des Sciences, El Manar, 2092 Tunis (Tunisia)
  2. Laboratoire de Materiaux et Cristallochimie, Faculte des Sciences, El Manar, 2092 Tunis (Tunisia), E-mail: gabderrahmen@yahoo.fr
  3. Institut des Materiaux Jean Rouxel, UMR CNRS 6502, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France)
  4. Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)
Publication Date:
OSTI Identifier:
21049530
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 10; Other Information: DOI: 10.1016/j.jssc.2007.08.011; PII: S0022-4596(07)00328-3; Copyright (c) 2007 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; ARSENATES; CHARGE DISTRIBUTION; ELECTRIC CONDUCTORS; IMPEDANCE; IONIC CONDUCTIVITY; IRON COMPOUNDS; MAGNETIC PROPERTIES; MILLI EV RANGE; MONOCLINIC LATTICES; MONOCRYSTALS; PARAMAGNETISM; POTASSIUM COMPOUNDS; POTASSIUM IONS; SPACE GROUPS; STRUCTURAL MODELS; TEMPERATURE RANGE 0013-0065 K; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0273-0400 K; TRICLINIC LATTICES; X-RAY DIFFRACTION