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Title: Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition

Abstract

In order to understand the structural transformations leading to high ionic conductivity of Cu{sup +} ions in Cu{sub 6}PS{sub 5}I argyrodite compound, the detailed structure analysis based on single-crystal X-ray diffraction has been performed. Below the phase transition at T{sub c}=(144-169)K Cu{sub 6}PS{sub 5}I belongs to monoclinic, ferroelastic phase (space group Cc) with ordered copper sublattice. Above T{sub c} delocalization of copper ions begins and crystal changes the symmetry to cubic superstructure with space group F-43c (a{sup '}=19.528A, z=32). Finally, above T{sub 1}=274K increasing disordering of the Cu{sup +} ions heightens the symmetry to F-43m (a=9.794A, z=4). In this work, the final structural model of two cubic phases is presented including the detailed temperature evolution of positions and site occupation factors of copper ions (R{sub 1}=0.0397 for F-43c phase, and 0.0245 for F-43m phase). Possible diffusion paths for the copper ions are represented by means of the atomic displacement factors and split model. The structural results coincide well with the previously reported non-Arrhenius behavior of conductivity and indicate significant change in conduction mechanism.

Authors:
 [1];  [2];  [3]
  1. W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. box 937, 50-204 Wroclaw (Poland). E-mail: a.gagor@int.pan.wroc.pl
  2. W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. box 937, 50-204 Wroclaw (Poland)
  3. Uzhhorod State University, Uzhhorod (Ukraine)
Publication Date:
OSTI Identifier:
20784771
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 178; Journal Issue: 11; Other Information: DOI: 10.1016/j.jssc.2005.08.015; PII: S0022-4596(05)00379-8; Copyright (c) 2005 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; ATOMIC DISPLACEMENTS; COPPER COMPOUNDS; COPPER IONS; DIFFUSION; IODIDES; IONIC CONDUCTIVITY; MONOCLINIC LATTICES; MONOCRYSTALS; PHASE SPACE; PHASE TRANSFORMATIONS; PHOSPHORUS COMPOUNDS; SPACE GROUPS; STRUCTURAL MODELS; SULFIDES; X-RAY DIFFRACTION

Citation Formats

Gagor, A., Pietraszko, A., and Kaynts, D. Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition. United States: N. p., 2005. Web. doi:10.1016/j.jssc.2005.08.015.
Gagor, A., Pietraszko, A., & Kaynts, D. Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition. United States. doi:10.1016/j.jssc.2005.08.015.
Gagor, A., Pietraszko, A., and Kaynts, D. Tue . "Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition". United States. doi:10.1016/j.jssc.2005.08.015.
@article{osti_20784771,
title = {Diffusion paths formation for Cu{sup +} ions in superionic Cu{sub 6}PS{sub 5}I single crystals studied in terms of structural phase transition},
author = {Gagor, A. and Pietraszko, A. and Kaynts, D.},
abstractNote = {In order to understand the structural transformations leading to high ionic conductivity of Cu{sup +} ions in Cu{sub 6}PS{sub 5}I argyrodite compound, the detailed structure analysis based on single-crystal X-ray diffraction has been performed. Below the phase transition at T{sub c}=(144-169)K Cu{sub 6}PS{sub 5}I belongs to monoclinic, ferroelastic phase (space group Cc) with ordered copper sublattice. Above T{sub c} delocalization of copper ions begins and crystal changes the symmetry to cubic superstructure with space group F-43c (a{sup '}=19.528A, z=32). Finally, above T{sub 1}=274K increasing disordering of the Cu{sup +} ions heightens the symmetry to F-43m (a=9.794A, z=4). In this work, the final structural model of two cubic phases is presented including the detailed temperature evolution of positions and site occupation factors of copper ions (R{sub 1}=0.0397 for F-43c phase, and 0.0245 for F-43m phase). Possible diffusion paths for the copper ions are represented by means of the atomic displacement factors and split model. The structural results coincide well with the previously reported non-Arrhenius behavior of conductivity and indicate significant change in conduction mechanism.},
doi = {10.1016/j.jssc.2005.08.015},
journal = {Journal of Solid State Chemistry},
number = 11,
volume = 178,
place = {United States},
year = {Tue Nov 15 00:00:00 EST 2005},
month = {Tue Nov 15 00:00:00 EST 2005}
}
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  • The {sup 1}H and {sup 87}Rb spin-lattice relaxation and spin-spin relaxation times in superionic Rb{sub 3}H(SeO{sub 4}){sub 2} single crystals grown by the slow evaporation method were measured over the temperature range 160-450 K. The temperature dependencies of the {sup 1}H T {sub 1}, T {sub 1} {sub {rho}} , and T {sub 2} are measured. In the ferroelastic phase, T {sub 1} differs from T {sub 1} {sub {rho}} , which is in turn different from T {sub 2}, although these three relaxation times converge to similar values near 410 K. This transition seems to occur at temperature whichmore » is about 40 K lower than the superionic transition temperature. The observation of liquid-like values of the {sup 1}H T {sub 1}, T {sub 1} {sub {rho}} , and T {sub 2} in the high temperature is compatible with the phase being superionic, indicating that the destruction and reconstruction of hydrogen bonds does indeed occur at high temperature. In addition, the {sup 87}Rb T {sub 1} and T {sub 2} values at high temperature were similar (on the order of milliseconds), a trend that was also observed for {sup 1}H T {sub 1} and T {sub 2}. This behavior is expected for most hopping-type ionic conductors, and could be attributed to interactions between the mobile ions and the neighboring group ions within the crystal. The motion giving rise to this liquid-like behavior is related to the superionic motion.« less