Abstract
The thermal expansion, structural changes and the site partitioning of Co and Mg in synthetic CoMgSiO4 olivine have been studied by in situ time-of-flight neutron powder diffraction as a function of temperature, between 25 and 1,000°C. Thermal expansion of the unit cell dimensions and volume are linear within this temperature range and give no indications of a phase transition, although the thermoelastic behaviour indicates a slight strain minimum around 700°C. Co2+ shows a strong preference for the M1 site throughout this temperature range with an oscillatory behaviour; it decreases slightly at about 300°C, climbing up to nearly its original value at around 800°C and then decreasing by about 30% at 1,000°C. This behaviour is in contrast with that of (Fe, Mg)2SiO4 olivine, in which the initial Fe2+ site preference for the M1 site switches to the M2 site beyond a cross-over temperature. The oscillatory site preference in (CoMg)-olivine as a function of temperature is reflected in the M–O polyhedral volume changes and M–O bond lengths, as well as, thermoelastic strain and atomic thermal displacement parameters. The imbalance between the increasing vibrational and decreasing configurational entropy contributions, together with covalent bonding effects rather than crystal field contributions, seem to drive the cation partitioning in (CoMg)-olivine.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Akamatsu T, Kumazawa M (1993) Kinetics of intracrystalline cation redistribution in olivine and its implications. Phys Chem Miner 19: 423–430
Bish DL (1981) Cation ordering in synthetic and natural Ni-Mg olivine. Am Mineral 66: 770–776
Burns RG (1970) Mineralogical application of crystal field theory. Cambridge University Press, Cambridge, p 224
Dove MT (2002) An introduction to the use of neutron scattering methods in mineral sciences. Eur J Mineral 14/2: 203–224
Ghose S, Wan C (1974) Strong site preference of Co2+ in olivine Co1.10Mg0.90SiO4. Contrib Mineral Petrol 47: 131–140
Henderson CMH, Redfern SAT, Smith RI, Knight KS, Charnock JM (2001) Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: a time-of-flight neutron powder diffraction and EXAFS study. Am Mineral 86:1170–1187
Larson AC, Von Dreele RB (1997) GSAS: general structure analysis system. Document LAUR 86–748, Los Alamos National Laboratory, New Mexico, USA
Müller-Sommer M, Hock R, Kirfel A (1997) Rietveld refinement study of the cation distribution in (Co, Mg)-olivine solid solution. Phys Chem Miner 24: 17–23
Ohashi Y (1982) STRAIN, a program to calculate the strain tensor from two sets of unit-cell parameters. In: Hazen RM, Finger LW (eds) Comparative crystal chemistry. Wiley, New York, pp 92–102
Redfern SAT, Henderson CMB, Knight KS, Wood BJ (1997) High temperature order-disorder in (Fe0.5Mn0.5)2SiO4 and (Mn0.5Mg0.5)2SiO4 olivines: an in situ neutron diffraction study. Eur J Mineral 9: 287–300
Redfern SAT, Artioli G, Rinaldi R, Henderson CMB, Knight KS, Wood BJ (2000) Octahedral cation ordering in olivine at high temperature. II: P an in situ neutron powder diffraction study on synthetic MgFeSiO4 (Fa50). Phys Chem Miner 27: 630–637
Rinaldi R (2002) Neutron scattering in mineral sciences. Eur J Mineral 14/2: 195–202
Rinaldi R, Artioli G, Wilson CC, McIntyre G (2000) Octahedral cation ordering in olivine at high temperature. I: in situ neutron single crystal diffraction studies on natural mantle olivines (Fa12 and Fa10). Phys Chem Miner 27: 623–629
Rinaldi R, Wilson CC (1996) Crystal dynamics by neutron time-of-flight Laue diffraction in olivine up to 1573 K using single frame methods. Sol State Commun 97/5: 395–400
Smyth JR, Jacobsen SD, Hazen RM (2000) Comparative crystal chemistry of orthosilicate minerals. In: Hazen RM, Downs RT (eds) High-temperature and high-pressure crystal chemistry. Reviews in Mineralogy and Geochemistry, vol. 41, Mineralogical Society of America and Geochemical Society, Washington, DC, pp 187–210
Shannon RD (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst A32: 751–767
Tsukimura K, Sasaki S (2000) Determination of cation distribution in (Co,Ni,Zn)2SiO4 olivine by synchrotron X-ray diffraction. Phys Chem Miner 27:234–241
Wood BJ (1974) Crystal field spectra of Ni2+ in olivine. Am Mineral 59: 244–248
Acknowledgements
Financial support to the first author is acknowledged from MIUR (Italian Ministry of University and Research; Grant No. 2004041033_4). The Italian National Research Council (CNR) is acknowledged for access to the ISIS Facility through the mutual Agreement (No.01/9001) between CNR and CCLRC. GDG wishes to thank the Bayerisches Geoinstitut, Universität Bayreuth for support during his stay at that Institution. CAG research was funded by the Deutscheforshungsgemeinschaft. Critical reading at an early stage by Subrata Ghose greatly improved the manuscript. Thanks are also due to W. Crichton and M. Welch for their very efficient and thorough reviews of the manuscript submitted to PCM Editor Milan Rieder.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Rinaldi, R., Gatta, G.D., Artioli, G. et al. Crystal chemistry, cation ordering and thermoelastic behaviour of CoMgSiO4 olivine at high temperature as studied by in situ neutron powder diffraction. Phys Chem Minerals 32, 655–664 (2005). https://doi.org/10.1007/s00269-005-0040-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00269-005-0040-3