Physics and Chemistry of Minerals

, Volume 45, Issue 1, pp 51–58 | Cite as

Phase boundary between cubic B1 and rhombohedral structures in (Mg,Fe)O magnesiowüstite determined by in situ X-ray diffraction measurements

  • Anna M. Dymshits
  • Konstantin D. Litasov
  • Anton Shatskiy
  • Artem D. Chanyshev
  • Ivan V. Podborodnikov
  • Yuji Higo
Original Paper


The phase relations and equation of state of (Mg0.08Fe0.92)O magnesiowüstite (Mw92) have been studied using the Kawai-type high-pressure apparatus coupled with synchrotron radiation. To determine the phase boundary between the NaCl-type cubic (B1) and rhombohedral (rB1) structures in Mw92, in situ X-ray observations were carried out at pressures of 0–35 GPa and temperatures of 300–1473 K. Au and MgO were used as the internal pressure markers and metallic Fe as oxygen fugacity buffer. The phase boundary between B1 and rB1 structures was described by a linear equation P (GPa) = 1.6 + 0.033 × T (K). The Clapeyron slope (dP/dT) determined in this study is close to that obtained at pressures above 70 GPa but steeper than that obtained for FeO. An addition of MgO to FeO structure expands the stability field of the rB1 phase to lower pressures and higher temperatures. Thus, the rB1 phase may be stabilized with respect to the B1 phase at a lower pressures. The pressure–volume–temperature equation of state of B1-Mw92 was determined up to 30 GPa and 1473 K. Fitting the hydrostatic compression data up to 30 GPa with the Birch–Murnaghan equation of state (EoS) yielded: unit cell volume (V 0,T0), 79.23 ± 4 Å3; bulk modulus (K 0,T0), 183 ± 4 GPa; its pressure derivative (K′ T ), 4.1 ± 0.4; (∂K 0,T /∂T) = −0.029 ± 0.005 GPa K‒1; a = 3.70 ± 0.27 × 10−5 K−1 and b = 0.47 ± 0.49 × 10−8 K−2, where α0,T  = a + bT is the volumetric thermal expansion coefficient. The obtained bulk modulus of Mw92 is very close to the value expected for stoichiometric iron-rich (Mg,Fe)O. This result confirms the idea that the bulk modulus of (Mg,Fe)O is greatly affected by the actual defect structure, caused by either Mg2+ or vacancies.


Magnesiowüstite (Mg,Fe)O Thermal equation of state Experiment High pressure Phase boundary 



This work was supported by Russian Science Foundation (No 14-17-00601) and Russian Foundation for Basic Research (No 15-35-20556). A. Dymshits was supported by state assignment project No 0330-2016-0006. Experiments were conducted under SPring-8 general research proposal No 2015A1496.


  1. Angel RJ, Alvaro M, Gonzalez-Platas J (2014) EosFit7c and a Fortran module (library) for equation of state calculations. Zeitschrift für Kristallographie Cryst Mater 229(5):405–419. doi: 10.1515/zkri-2013-1711 Google Scholar
  2. Dorogokupets PI, Dewaele A (2007) Equations of state of MgO, Au, Pt, NaCl-B1, and NaCl-B2: internally consistent high-temperature pressure scales. High Press Res 27:431–446. doi: 10.1080/08957950701659700 CrossRefGoogle Scholar
  3. Fei Y (1996) Crystal chemistry of FeO at high pressure and temperature. In: Dyar M, McCammon C, Shaefer M (eds) Mineral spectroscopy: a tributeRoger G. Burns, vol Special Publication 5. The Geochemical Society, Houston, pp 243–254Google Scholar
  4. Fei Y (1999) Effects of temperature and composition on the bulk modulus of (Mg, Fe)O. Am Miner 84:272–276. doi: 10.2138/am-1999-0308 CrossRefGoogle Scholar
  5. Fei Y, Mao H-K (1994) In Situ determination of the NiAs phase of FeO at high pressure and temperature. Science 266:1678–1680CrossRefGoogle Scholar
  6. Fei Y, Mao H-K, Mysen BO (1991) Experimental determination of element partitioning and calculation of phase relations in the MgO-FeO-SiO2 system at high pressure and high temperature. J Geophys Res Solid Earth 96:2157–2169. doi: 10.1029/90JB02164 CrossRefGoogle Scholar
  7. Fei Y, H-k Mao, Shu J, Hu J (1992) P-V-T equation of state of magnesiowüstite (Mg0.6Fe0.4)O. Phys Chem Miner 18:416–422. doi: 10.1007/bf00200964 CrossRefGoogle Scholar
  8. Fei Y, Zhang L, Corgne A, Watson H, Ricolleau A, Meng Y, Prakapenka V (2007) Spin transition and equations of state of (Mg, Fe)O solid solutions. Geophys Res Lett 34:L17307. doi: 10.1029/2007GL030712 CrossRefGoogle Scholar
  9. Fischer RA, Campbell AJ, Shofner GA, Lord OT, Dera P, Prakapenka VB (2011) Equation of state and phase diagram of FeO. Earth Planet Sci Lett 304:496–502. doi: 10.1016/j.epsl.2011.02.025 CrossRefGoogle Scholar
  10. Haavik C, Stølen S, Hanfland M, Catlow CRA (2000) Effect of defect clustering on the high-pressure behaviour of wüstite. High-pressure X-ray diffraction and lattice energy simulations. Phys Chem Chem Phys 2:5333–5340CrossRefGoogle Scholar
  11. Holland TJB, Redfern SAT (1997) Unit cell refinement from powder diffraction data: the use of regression diagnostics. Mineral Mag 61:65–77. doi: 10.1180/minmag.1997.061.404.07 CrossRefGoogle Scholar
  12. Jackson I, Khanna SK, Revcolevschi A, Berthon J (1990) Elasticity, shear-mode softening and high-pressure polymorphism of wüstite (Fe1-xO). J Geophys Res Solid Earth 95:21671–21685. doi: 10.1029/JB095iB13p21671 CrossRefGoogle Scholar
  13. Jacobsen SD (2002) Structure and elasticity of single-crystal (Mg, Fe) O and a new method of generating shear waves for gigahertz ultrasonic interferometry. J Geophys Res 107(B2). doi: 10.1029/2001JB000490
  14. Kantor IY, Dubrovinsky LS, McCammon CA (2006) Spin crossover in (Mg, Fe) O: a Mossbauer effect study with an alternative interpretation of x-ray emission spectroscopy data. Phys Rev B 73:100101CrossRefGoogle Scholar
  15. Katsura T et al (2004) A large-volume high-pressure and high-temperature apparatus for in situ X-ray observation, ‘SPEED-Mk. II’. Phys Earth Planet Inter 143:497–506CrossRefGoogle Scholar
  16. Kondo T, Ohtani E, Hirao N, Yagi T, Kikegawa T (2004) Phase transitions of (Mg, Fe)O at megabar pressures. Phys Earth Planet Inter 143–144:201–213. doi: 10.1016/j.pepi.2003.10.008 CrossRefGoogle Scholar
  17. Lin J-F et al (2005) Spin transition of iron in magnesiowustite in the Earth’s lower mantle. Nature 436:377–380. doi: 10.1038/nature03825
  18. Lavrent’ev YG, Karmanov NS, Usova LV (2015) Electron probe microanalysis of minerals: microanalyzer or scanning electron microscope? Russ Geol Geophys 56:1154–1161. doi: 10.1016/j.rgg.2015.07.006 CrossRefGoogle Scholar
  19. Litasov K, Ohtani E, Sano A, Suzuki A, Funakoshi K (2005) In situ X-ray diffraction study of post-spinel transformation in a peridotite mantle: implication for the 660-km discontinuity. Earth Planet Sci Lett 238:311–328. doi: 10.1016/j.epsl.2005.08.001 CrossRefGoogle Scholar
  20. Mao HK, Bell PM (1979) Equations of state of MgO and ε-Fe under static pressure conditions. J Geophys Res Solid Earth 84:4533–4536. doi: 10.1029/JB084iB09p04533 CrossRefGoogle Scholar
  21. Mao H-k, Shu J, Hu J, Hemley RJ (1996) The wüstite enigma. Phys Earth Planet Inter 96:135–145CrossRefGoogle Scholar
  22. Mao W, Shu J, Hu J, Hemley R, H-k Mao (2002) Displacive transition in magnesiowüstite. J Phys Condens Matter 14:11349CrossRefGoogle Scholar
  23. McCammon C (1993) Effect of pressure on the composition of the lower mantle end member FexO. Science 259:66–68. doi: 10.1126/science.259.5091.66 CrossRefGoogle Scholar
  24. Richet P, Mao H-K, Bell PM (1989) Bulk moduli of magnesiowüstites from static compression measurements. J Geophys Res Solid Earth 94:3037–3045. doi: 10.1029/JB094iB03p03037 CrossRefGoogle Scholar
  25. Sata N, Shen G, Rivers ML, Sutton SR (2002) Pressure-volume equation of state of the high-pressure $B2$ phase of NaCl. Phys Rev B 65:104114CrossRefGoogle Scholar
  26. Shu J, Mao HK, Hu J, Fei Y, Hemley RJ (1998) Single-crystal X-ray diffraction of Wüstite to 30 GPa hydrostatic pressure. Neues Jahrbuch fur Mineralogie Abhandlungen 172:309–323Google Scholar
  27. Sokolova TS, Dorogokupets PI, Litasov KD (2013) Self-consistent pressure scales based on the equations of state for ruby, diamond, MgO, B2–NaCl, as well as Au, Pt, and other metals to 4 Mbar and 3000 K. Russ Geol Geophys 54:181–199. doi: 10.1016/j.rgg.2013.01.005 CrossRefGoogle Scholar
  28. Sokolova TS, Dorogokupets PI, Dymshits AM, Danilov BS, Litasov KD (2016) Microsoft excel spreadsheets for calculation of P–V–T relations and thermodynamic properties from equations of state of MgO, diamond and nine metals as pressure markers in high-pressure and high-temperature experiments. Comput Geosci 94:162–169. doi: 10.1016/j.cageo.2016.06.002 CrossRefGoogle Scholar
  29. Solomatova NV et al (2016) Equation of state and spin crossover of (Mg, Fe) O at high pressure, with implications for explaining topographic relief at the core-mantle boundary. Am Mineral 101:1084–1093CrossRefGoogle Scholar
  30. Wicks JK, Jackson JM, Sturhahn W (2010) Very low sound velocities in iron-rich (Mg, Fe)O: Implications for the core-mantle boundary region. Geophys Res Lett. doi: 10.1029/2010GL043689 Google Scholar
  31. Wicks JK, Jackson JM, Sturhahn W, Zhuravlev KK, Tkachev SN, Prakapenka VB (2015) Thermal equation of state and stability of (Mg0.06Fe0.94)O. Phys Earth Planet Inter 249:28–42. doi: 10.1016/j.pepi.2015.09.003 CrossRefGoogle Scholar
  32. Will G, Hinze E, Nuding W (1980) The compressibility of FeO measured by energy dispersive X-ray diffraction in a diamond anvil squeezer up to 200 kbar. Phys Chem Miner 6:157–167. doi: 10.1007/bf00311052 CrossRefGoogle Scholar
  33. Yagi T, Suzuki T, Akimoto S-I (1985) Static compression of wüstite (Fe0.98O) to 120 GPa. J Geophys Res Solid Earth 90:8784–8788. doi: 10.1029/JB090iB10p08784 CrossRefGoogle Scholar
  34. Zhang J (2000) Effect of defects on the elastic properties of wüstite. Phys Rev Lett 84:507CrossRefGoogle Scholar
  35. Zhang L, Gong Z, Fei Y (2008) Shock-induced phase transitions in the MgO–FeO system to 200 GPa. J Phys Chem Solids 69:2344–2348. doi: 10.1016/j.jpcs.2008.04.006 CrossRefGoogle Scholar
  36. Zou G, Mao H, Bell P, Virgo D (1980) High pressure experiments on the iron oxide wüstite (Fe1–XO), vol 79. Year Book Carnegie Institution Washington, WashingtonGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • Anna M. Dymshits
    • 1
  • Konstantin D. Litasov
    • 1
    • 2
  • Anton Shatskiy
    • 1
    • 2
  • Artem D. Chanyshev
    • 1
    • 2
  • Ivan V. Podborodnikov
    • 1
    • 2
  • Yuji Higo
    • 3
  1. 1.Sobolev Institute of Geology and Mineralogy Siberian Branch of Russian Academy of ScienceNovosibirskRussia
  2. 2.Novosibirsk State UniversityNovosibirskRussia
  3. 3.SPring-8, Japan Synchrotron Radiation Research InstituteKoutoJapan

Personalised recommendations