Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
American Mineralogist Don't get GSW? Talk to your librarian.
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
American Mineralogist; August-September; v. 93; no. 8-9; p. 1260-1272; DOI: 10.2138/am.2008.2690
© 2008 Mineralogical Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Burton, B. P.
Right arrow Articles by Ballaran, T. B.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

A low-temperature phase diagram for ilmenite-rich compositions in the system Fe2O3-FeTiO3

Benjamin P. Burton1,*, Peter Robinson2, Suzanne A. McEnroe2, Karl Fabian2 and Tiziana Boffa Ballaran3

1 NIST, 100 Bureau Drive, Gaithersburg, Maryland 20878, U.S.A.
2 Geological Survey of Norway, N-7491, Trondheim, Norway
3 Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany

Correspondence: * E-mail: benjamin.burton{at}nist.gov

An approximate low-temperature, metastable phase diagram is drawn for the system (1 – X) Fe2O3-(X)FeTiO3. It is based on published and new magnetic data from nine synthetic samples with bulk compositions in the range 0.6 < X < 1.0. Fields are plotted for (1) the paramagnetic phase (PM); the Fe2O3-rich ferrimagnetic phase (FM); (2) the FeTiO3-rich antiferromagnetic phase (AF); and (3) a re-entrant spin-glass phase (RSG). In addition, two subfields are plotted: (1) FM', a subfield of the FM-phase, which occurs below a characteristic temperature TK, at which the magnetic susceptibility drops sharply on cooling, and (2) PM', a subfield of the PM-phase (traditionally called superparamagnetic) forms below a sharp rise in susceptibility at TS, and exhibits measurable dispersion in the magnetic susceptibility at T < TS.

The diagram is drawn with a bicritical point, T{lambda}{lambda}', at X {approx} 0.87, T {approx} 39 K, which is the intersection of second-order magnetic phase boundaries for the paramagnetic -> ferrimagnetic [PM(PM') -> FM] transition, TC(X), and the PM(PM') -> AF transition, TN(X). In addition, the RSG phase is plotted as one of four stable phases at T{lambda}{lambda}', a construction that is not required by the phase rule, but is strongly favored by the physics of competition between the incompatible magnetically ordered structures of the FM- and AF-phases.

These phase relations are at such low temperature as to be of little consequence for terrestrial magnetism, however, they may well be essential for interpreting the magnetism of the Moon, Mars, and other cold planets. These phase relations are also essential for the characterization of fine natural and synthetic intergrowths, and for understanding magnetic materials for low-temperature technological applications.

Key Words: Hematite-ilmenite • magnetic properties • spin glass • phase diagram






JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2009 by Mineralogical Society of America