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Title: Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/)

Abstract

It is shown that Hong's NASICON solid solution range is intrinsically stable for T > 600 K. With the help of electrochemical and calorimetric experiments, complete thermochemical information of Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/ (0 less than or equal to x less than or equal to 3) compositions has been elucidated, i.e., formation enthalpies, standard entropies, and molar volume (1.5-1000K). For the purpose of a precise evaluation of the electrochemical values the specific heats of ZrP/sub 2/O/sub 7/ and Na/sub 2/ZrSi/sub 2/O/sub 7/ have also been determined. A thermodynamic mixture model is constructed showing that the solid solution is entropy stabilized. The energetic interaction has a destabilizing influence. The zero-point entropy and the excess entropy at higher temperatures suggest a partial ordering (Si/P) at higher temperatures. A miscibility gap, however, which is predicted for T less than or equal to 600 K by the model, could not be found due to the slow kinetics or because of a simultaneous phase transformation. The obtained values clearly show that NASICON is thermodynamically unstable with respect to a reaction with elementary sodium. The instability increases with increasing P content.

Authors:
; ;
Publication Date:
Research Org.:
Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany, F.R.)
OSTI Identifier:
7201613
Resource Type:
Journal Article
Journal Name:
J. Solid State Chem.; (United States)
Additional Journal Information:
Journal Volume: 72:1
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; PHOSPHORUS OXIDES; PHASE STUDIES; THERMODYNAMIC PROPERTIES; SILICON OXIDES; SODIUM OXIDES; ZIRCONIUM OXIDES; INFRARED SPECTRA; SOLID SOLUTIONS; THEORETICAL DATA; THERMODYNAMICS; ALKALI METAL COMPOUNDS; CHALCOGENIDES; DATA; DISPERSIONS; INFORMATION; MIXTURES; NUMERICAL DATA; OXIDES; OXYGEN COMPOUNDS; PHOSPHORUS COMPOUNDS; PHYSICAL PROPERTIES; SILICON COMPOUNDS; SODIUM COMPOUNDS; SOLUTIONS; SPECTRA; TRANSITION ELEMENT COMPOUNDS; ZIRCONIUM COMPOUNDS; 360204* - Ceramics, Cermets, & Refractories- Physical Properties

Citation Formats

Warhus, U, Maier, J, and Rabenau, A. Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/). United States: N. p., 1988. Web. doi:10.1016/0022-4596(88)90014-X.
Warhus, U, Maier, J, & Rabenau, A. Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/). United States. https://doi.org/10.1016/0022-4596(88)90014-X
Warhus, U, Maier, J, and Rabenau, A. 1988. "Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/)". United States. https://doi.org/10.1016/0022-4596(88)90014-X.
@article{osti_7201613,
title = {Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/)},
author = {Warhus, U and Maier, J and Rabenau, A},
abstractNote = {It is shown that Hong's NASICON solid solution range is intrinsically stable for T > 600 K. With the help of electrochemical and calorimetric experiments, complete thermochemical information of Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/ (0 less than or equal to x less than or equal to 3) compositions has been elucidated, i.e., formation enthalpies, standard entropies, and molar volume (1.5-1000K). For the purpose of a precise evaluation of the electrochemical values the specific heats of ZrP/sub 2/O/sub 7/ and Na/sub 2/ZrSi/sub 2/O/sub 7/ have also been determined. A thermodynamic mixture model is constructed showing that the solid solution is entropy stabilized. The energetic interaction has a destabilizing influence. The zero-point entropy and the excess entropy at higher temperatures suggest a partial ordering (Si/P) at higher temperatures. A miscibility gap, however, which is predicted for T less than or equal to 600 K by the model, could not be found due to the slow kinetics or because of a simultaneous phase transformation. The obtained values clearly show that NASICON is thermodynamically unstable with respect to a reaction with elementary sodium. The instability increases with increasing P content.},
doi = {10.1016/0022-4596(88)90014-X},
url = {https://www.osti.gov/biblio/7201613}, journal = {J. Solid State Chem.; (United States)},
number = ,
volume = 72:1,
place = {United States},
year = {1988},
month = {1}
}