Study of the precise location of the wustite phase boundaries and the dependence of the partial pressure of oxygen on the temperature and composition of the solid phase was made. From the pressure of oxygen, the temperature and the composition thermodynamic quantities can be determined

Ackerman, R. J.

Sandford, R. W., Jr.

English

NASA Technical Reports Server

December 1968	 Brief 68-10408 
•	 AEC-NASA TECH BRIEF 
ij755
- 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
The Thermodynamic Properties of the Wustite Phase Are Studied 
The thermodynamic properties of the wustite 
(FeOi+) phase have been measured over a tempera-
ture range of 970-1280 1 K by determining the values of 
x for known oxygen pressures. The study was con- 
ducted by R. J. Ackermann and R. W. Sandford, Jr. 
of Argonne National Laboratory, Argonne, Illinois, 
and their complete findings have been published in 
"A Thermodynamic Study of the Wustite Phase," 
ANL-7250, September 1966. In the report, free ener-
gies, ènthalpies and entropies, as well as their respec-
tive trends with composition and temperature, were 
derived from the measured quantities, the Gibbs-
Duhem equation and colorimetric data. The behavior 
of the partial molar quantities of oxygen and iron sug-
gest the existence of a complicated temperature-de-
pendent microstructure or superstructure. 
The immediate goals of the present study were to 
determine: 1) the precise location of the wustite phase 
boundaries, and 2) the dependence of the partial pres-
sure of oxygen on the temperature and composition of 
the solid phase. The concentration of effort was in the 
range of 9500 to 13001 K where the behavior is of ma-
jor interest. 
The characteristics of the vaporization behavior of 
refractory metal-oxide systems have been a problem 
extensively studied in high-temperature chemistry. 
This involves not only the identification of the various 
vapor species over a condensed phase, but also the 
determination of the chance in free energy, enthalpy, 
and entropy that accompany vaporization. The prob-
lem which has complicated the thermodynamic anal-
ysis of almost every vaporization study. is the uncer-
tainty of the thermodynamic properties of the solid 
phase which result from its deviation from known 
stoichiometry at the high temperatures necessary to 
produce measurable vaporization. 
Many investigators have studied the iron-oxygen 
system, particularly the FeOl+X region. Nevertheless 
a clear understanding of the system required further 
study, especially at temperatures less than 1000°C, 
because of numerous discrepancies in previous studies 
and because of the current use of an iron-wustite 
electrode as a standard for the high-temperature, sol-
id-galvanic-cell determinations of the partial molar 
free energy of oxygen in nonstoichiometric metal 
oxides. 
To determine the partial pressure of oxygen over a 
known composition of wustite at a given temperature, 
a system was devised for controlling and determining 
the three experimental variables of the macroscopic 
system (the pressure of oxygen, the temperature, and 
the composition of the solid phase). By applying the 
phase rule, the wustite phase was known to have two 
degrees of freedom. Thus when any two of the three 
variables are controlled, the third is fixed. The experi-
ment was designed to control the pressure of oxygen 
and the temperature, and to determine the composi-
tion of FeOl+X as a function of these controlled var-
iables. 
From the pressure of oxygen, the temperature and 
the composition, the thermodynamic quantities in-
cluding the free energy, enthalpy, and entropy can be 
determined.	 (continued overleaf) 
This document was prepared under the sponsorship of the Atomic 	 liability resulting from the use of the information contained in this 
Energy Commission and/or the National Aeronautics and Space document, or warrants that the use of any information, apparatus, 
Administration. Neither the United States Government nor any per- 	 method, or process disclosed in this document may not infringe pri-
son acting on behalf of the United States Government assumes any vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19680000408 2020-03-12T05:56:17+00:00Z
Notes: 
I. A better understanding of the FeO system may 
be of interest to metallurgists and those using re-
fractories. 
2. The report is available from Clearinghouse for 
Federal Scientific and Technical Information, 
Springfield, Va., 22151: price $3.00 (microfiche 
$0.65). Inquiries may also be directed to: 
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B68-10408 
Source: R. J. Ackerman, R. W. Sandford, Jr.

of the Chemistry Division

(ARG- 10200)
Patent status: 
Inquiries about obtaining rights for commercial use 
of this innovation may be made to: 
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 68-10408	 Category 03


The thermodynamic properties of the wustite phase are studied

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server