Other| April 01, 1996 Magnetic properties of the magnetite-spinel solid solution; Curie temperatures, magnetic susceptibilities, and cation ordering Richard J. Harrison; Richard J. Harrison University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom Search for other works by this author on: GSW Google Scholar Andrew Putnis Andrew Putnis Search for other works by this author on: GSW Google Scholar American Mineralogist (1996) 81 (3-4): 375–384. https://doi.org/10.2138/am-1996-3-412 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Richard J. Harrison, Andrew Putnis; Magnetic properties of the magnetite-spinel solid solution; Curie temperatures, magnetic susceptibilities, and cation ordering. American Mineralogist 1996;; 81 (3-4): 375–384. doi: https://doi.org/10.2138/am-1996-3-412 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Curie temperatures (Tc) of the (Fe3O4)x(MgAl2O4)1–x solid solution have been determined from measurements of magnetic susceptibility (χ) vs. temperature. The trend in Tc vs. composition extrapolates to 0 K at x = 0.27. This behavior is rationalized in terms of the trend in cation distribution vs. composition suggested by Nell and Wood (1989), with Fe occurring predominantly on tetrahedral sites for x < 0.27.High-temperature x-T curves are nonreversible because of the processes of cation ordering and exsolution, which occur in the temperature range 400–650 °C. The Curie temperature of single-phase material is shown to be sensitive to the state of nonconvergent cation order, with a difference in Tc of more than 70 °C being observed between a sample quenched from 1400 °C and the same sample after heating to 650 °C. This interaction between magnetic and chemical ordering leads to thermal hysteresis behavior such that Tc measured during heating experiments is approximately 10 °C higher than that measured during cooling. The hysteresis is due to a reversible difference in the state of cation order during heating and cooling caused by a kinetic lag in the cation-ordering behavior.Samples with compositions in the range 0.55 < x < 0.1 undergo exsolution to a mixture of ferrimagnetic and paramagnetic phases after heating to 650 °C. Room-temperature hysteresis loops of the starting material and the high-temperature experiment products are compared. All starting materials are multidomain with coercivities Hc < 1.26 mT and Mrs/Ms < 0.051. Samples that exsolved during the experiments have coercivities up to 20 mT and Mrs/Ms up to 0.36. This change in hysteresis properties is caused by grain subdivision during exsolution and implies a transition in the magnetic domain state from multi- to single-domain. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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Harrison et al. (1996) studied this question.