THERMODYNAMICS OF CUSICON OXIDATION
R.J. Schaffer
1,2
*, R.V. Kumar
2
, and A.E. Ingham
1
1
Alpha Fry, Tandem House, Marlowe Way, Croydon, Surrey CR0 4XS, UK
2
Department of Materials Science and Metallurgy, University of Cambridge,
Pembroke Street, Cambridge CB2 3QZ, UK
(Refereed)
(Received July 7, 1998; Accepted August 24, 1998)
ABSTRACT
The solid electrolyte CuZr
2
P
3
O
12
was synthesized and its oxidation to
Cu
1/2
Zr
2
P
3
O
12
was investigated between 400 and 800°C. A cell Pt,
O
2
cusicon
YSZO
2
reference
, Pt was used to study the thermodynamics of the
oxidation. It was found that G
O
=-108596 + 87.562 T in the temper-
ature range investigated. © 1999 Elsevier Science Ltd
KEYWORDS: A. oxides, A. ceramics, C. electrochemical measurements, D.
phase equilibria, D. thermodynamic properties
INTRODUCTION
Cusicon (Cu super ionic conductor), CuZr
2
P
3
O
12
, which is isostructural with nasicon [1], was
first discussed by McInerney and Morris [2] and synthesized by Yao and Fray [3] in 1983.
Much interest has centered on the possible use of the material as a solid electrolyte and
cusicon [4 – 8], and other materials with the general formula A'
1
A
2
M
2
(XO
4
)
3
have been the
subject of several studies by different authors [9 –22].
In addition to CuZr
2
P
3
O
12
, there exists a form of cusicon containing divalent copper,
Cu
0.5
Zr
2
P
3
O
12
[15,23–25]. Indeed, it has been suggested [11,26] that there exists a solid
solution Cu
x
Zr
2
P
3
O
12
, where 0.5 x 1. Although details vary considerably between
authors, two synthetic approaches are provided in the literature: a thermal solid state route
[3–5] to Cu
I
Zr
2
P
3
O
12
and a sol-gel route [25,27] to Cu
II
0.5
Zr
2
P
3
O
12
.
*To whom correspondence should be addressed, at Johnson Matthey CMD, Uttoxeter Road, Meir,
Stoke-on-Trent, ST3 7XW, UK.
Materials Research Bulletin, Vol. 34, No. 7, pp. 1153–1164, 1999
Copyright © 1999 Elsevier Science Ltd
Printed in the USA. All rights reserved
0025-5408/99/$–see front matter
PII S0025-5408(99)00101-4
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