Effect of dilution on the spin pairing transition in rhombohedral carbonates
Abstract
The compressibility of an iron-bearing magnesite (Mg_(0.87)Fe^(2+)_(0.12)Ca_(0.01))CO_3 was determined by means of single crystal diffraction up to 64 GPa. Up to 49 GPa the pressure-evolution of the unit cell volume of the solid solution with 12% of Fe^(2+) can be described by a third-order Birch-Murnaghan equation of state with parameters V_0 = 281.0(5)Å^3, K_0 = 102.8(3) GPa, K'_0 = 5.44. The spin pairing of the Fe^(2+) d-electrons occurs between 49 and 52 GPa, as evidenced by a discontinuous volume change. The transition pressure is increased by about 5 GPa compared with the iron end-member; an effect consistent with a cooperative contribution of adjacent clusters to the spin transition. The trend is, however, opposite in the periclase-wstite solid solution. Differences among the two structures, in particular in the Fe-Fe interactions, that might explain the different behavior are discussed.
Additional Information
© 2010 Taylor & Francis. Received 19 January 2010; final version received 12 April 2010. The UNLV High Pressure Science and Engineering Center is supported by DOE-NNSA Cooperative Agreement DE- FC52-06NA262740. Diffraction data were collected at HPCAT (Sector 16), APS, Argonne National Laboratory. HPCAT is supported by CIW, CDAC, UNLV and LLNL through funding from DOE-NNSA, DOE-BES and NSF. APS is supported by DOE-BES, under Contract No. DE-AC02-06CH11357. We thank GSECARS and COMPRES for the use of the Gas loading System. HPSynC is supported as part of the Efree, an Energy Frontier Research Center funded by DOE-BES under Award DE-SC0001057.Additional details
- Eprint ID
- 18828
- Resolver ID
- CaltechAUTHORS:20100628-100843624
- DE-AC02-06CH11357
- Department of Energy-Office of Basic Energy Sciences (DOE-BES)
- Created
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2010-06-28Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field