McCammon et al. Progress in Earth and Planetary Science (2016) 3:10
DOI 10.1186/s40645-016-0089-2

Progress in Earth andPlanetary Science

RESEARCH ARTICLE

Open AccessSound velocities of bridgmanite fromdensity of states determined by nuclear
inelastic scattering and first-principles
calculations
Catherine McCammon1*, Razvan Caracas2, Konstantin Glazyrin3, Vasily Potapkin1, Anastasia Kantor1,4,
Ryosuke Sinmyo1,6, Clemens Prescher1,7, Ilya Kupenko1,4,8, Aleksandr Chumakov4,5 and Leonid Dubrovinsky1

Abstract
Sound velocities of bridgmanite measured in the laboratory are a key to deciphering the composition of
the lower mantle. Here, we report Debye sound velocities determined using nuclear inelastic scattering(NIS) for one majorite composition (Mg0.82Fe0.18SiO3) and five bridgmanite compositions (Mg0.82Fe0.18SiO3,
Mg0.86Fe0.14Si0.98Al0.02O3, Mg0.88Fe0.12SiO3, Mg0.6Fe0.4Si0.63Al0.37O3, Mg0.83Fe0.15Si0.98Al0.04O3) measured in adiamond anvil cell at pressures up to 89 GPa at room temperature. Debye sound velocities for majorite
determined from NIS are consistent with literature data from Brillouin scattering and ultrasonics, while
Debye sound velocities for bridgmanite are significantly lower than literature values from the same
methods. We calculated partial and total density of states (DOS) for MgSiO3 and FeSiO3 bridgmanite using
density functional theory and demonstrate that Debye sound velocities calculated from the reduced DOS
using the same approach as for the experimental data (i.e., the limit of D(E)/E2 as energy goes to zero) givethe same sound velocities for each phase irrespective of which partial DOS is used. In addition, we showthat Debye sound velocities calculated using this approach are consistent with values obtained from thecalculation of the full elastic tensor. Comparison of the calculated DOS with the one obtained from NIS
indicates that the experimental DOS has enhanced intensity at low energies that leads to a different slopeof the DOS and hence a lower sound velocity. This effect is present in all of the bridgmanite samples
examined in this study.
Keywords: Elasticity, Perovskite, Nuclear resonance, Sound velocity, Lower mantle, Density functional theory

Background
Insight into the accretion of the Earth and its subsequent differentiation can be gained through knowledge of the present-day Earth composition. The
lower mantle in particular has been the focus ofmuch attention as well as controversy, and questions
such as how closely it approximates a chondritic
composition have occupied geochemists for decades.
Comparison of laboratory measurements of elastic
wave velocities of lower mantle minerals with seismic data has played a crucial role in the discussion* Correspondence: catherine.mccammon@uni-bayreuth.de1
Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth 95440, Germany
Full list of author information is available at the end of the article

starting with Birch (1952), and experimental techniques such as inelastic X-ray scattering (e.g., Fiquet
et al. 2004), Brillouin scattering (e.g., Sinogeikin andBass 2002; Jackson et al. 2005; Murakami et al. 2007;
Murakami et al. 2008), ultrasonics (e.g., Irifune et al.
2008; Gwanmesia et al. 2009; Liu et al. 2015), andimpulsive stimulated scattering (e.g., Crowhurst et al.
2008) have provided important results on transitionzone and lower mantle minerals. In situ measurements are important, because some transitions (forexample, spin transitions) are not quenchable, and may influence the elastic properties of iron-containing minerals.
Nuclear inelastic scattering (NIS) offers the attractive
possibility to determine elastic wave velocities of iron-© 2016 McCammon et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 2 of 10

Table 1 Starting materials used for DAC experiments
Sample

Phase

xFe

xAl

xMg

xSi

Fe3+/ΣFe precursor

Fe3+/ΣFe bridgmanite

57

Fe enrichment

Ref

U1219

Majorite

0.18(1)00.82(1)1.00(1)0.09(2)

0.15–0.20

0.9

a, b

SL16

Bridgmanite

0.14(2)0.02(1)0.86(3)0.98(4)–0.30(5)

0.6

c

SL18

Pyroxene

0.12(1)00.88(2)1.00(1)n.a.

0.15(4)

0.6

d, e

S4850

Bridgmanite

0.40(3)0.37(2)0.60(3)0.63(3)–0.80(5)

0.9

f

S4883

Bridgmanite

0.15(2)0.04(1)0.83(2)0.98(1)–0.27(7)0.6

g

a McCammon and Ross (2003); b McCammon et al. (2010); c Lauterbach et al. (2000); d Lauterbach (2000); e McCammon et al. (2008); f Potapkin et al. (2013);
g this study
n.a. not analyzed

containing minerals in the laser-heated diamond anvil
cell through direct measurement of the partial density ofstates (e.g., Sturhahn and Jackson 2007), and results for
mantle minerals have already been reported for ferropericlase (Lin et al. 2006; Wicks et al. 2010; Chen et al.
2012; Sinmyo et al. 2014), orthoenstatite (Jackson et al.
2009) and post-perovskite (Mao et al. 2006). So far, however, no investigations using NIS have been carried out
on the Earth’s most abundant mineral that constitutes
the bulk of the lower mantle, namely bridgmanite.
Computational studies provide an important complement to experimental measurements and allow a more
extensive probe of parameter space. Methods have advanced substantially in recent years to enable densities
and elastic wave velocities of candidate lower mantle assemblages to be calculated for the appropriate compositions at relevant pressure and temperature compositions(e.g., Wang et al. 2015 and references therein). Electronic transitions in iron present a challenge, however,and the apparent inconsistency between experimental
and computational results on the stability of the intermediate spin state of Fe2+ in bridgmanite remains controversial (e.g., Stackhouse 2008; McCammon et al.
2013; Shukla et al. 2015). Nevertheless, a strong advantage of computations is the capability to calculate a wide
range of properties including experimental observables
based on vibrational density of states (DOS), for example
infrared spectra of hydrous post-perovskite (Townsend
et al. 2015). The combination of theoretical DOS calculations with experimental determinations using NIS provides a powerful new tool to understand the vibrational
properties of iron-containing phases.
In this work, we present an experimental study using
NIS to determine sound velocities of five different compositions of (Mg,Fe)(Si,Al)O3 bridgmanite at pressures
between 0 and 89 GPa at room temperature, including acomparison with results for (Mg,Fe)(Si,Al)O3 majorite
with the same composition. We present a parallel theoretical study to calculate the DOS of two bridgmanite
end-members (MgSiO3 and FeSiO3) at comparable pressures that provides insight into the anomalous experimental results.

Fig. 1 Comparison of U1219 sample data for the majorite andbridgmanite phases at 33 GPa. a NIS spectra. b pDOS (upper) andreduced pDOS (lower). Majorite was measured first and thentransformed to bridgmanite by laser heating, after which the NIS
data for bridgmanite were collectedMcCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 3 of 10

Fig. 2 Influence of pressure on U1219 bridgmanite. a NIS spectra. b pDOS (upper) and reduced pDOS (lower). Data were collected oncompression during the same beamtime experiment and follow on from the spectra shown in Fig. 1

Fig. 3 Influence of pressure on SL18 bridgmanite. a Selected NIS spectra. b Selected pDOS (upper) and reduced pDOS (lower). The SL18 pyroxene
starting material was transformed to bridgmanite by laser heating in the DAC, and data were collected during three different beamtime
experiments: #1—17, 36, 62, and 75 GPa; #2—50 GPa (not shown); and #3—65 GPa

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 4 of 10

Methods
The starting materials for the DAC experiments arelisted in Table 1. Sample S4883 was synthesized fromorthopyroxene loaded into a Re capsule in a Kawai-type
multianvil press with a LaCrO3 heater assembly and
W75Re25/W97Re03 thermocouple at 26 GPa and 2000 °C
for 40 min (Keppler and Frost 2005). The compositionsof the starting materials were determined using the electron microprobe and conventional (radioactive point
source) Mössbauer spectroscopy.
NIS measurements were made using panoramic DACs
that were designed and constructed at Bayerisches
Geoinstitut. For each experiment, a starting material in
the form of powder was loaded into a Be gasket together
with small ruby chips for pressure determination using
the ruby scale of Mao et al. (1986). Generally, LiF or
NaCl was used as a pressure medium. The diameters ofthe diamond culets and opening holes in the gaskets varied depending on the pressure range of the experiment.
The samples were laser-heated in the DAC using a portable system mounted on the beamline incorporating either single-sided (Dubrovinsky et al. 2009) or doublesided (Kupenko et al. 2012) laser heating.
The NIS data were collected at ambient conditions on
the nuclear resonance beamline ID18 at the European
Synchrotron Radiation Facility (Rüffer and Chumakov1996) between 2008 and 2010. Further details of the NIS
setup and data analysis are given in Glazyrin et al. (2013)
and references therein. Nuclear forward scattering (NFS)
data were collected at the same time as the NIS data tomonitor the electronic state of iron, and X-ray diffraction
was used to confirm the identity of bridgmanite off-line
after laser heating. The NIS data were collected typicallyover a range of −80 to 80 meV around the 57Fe nuclear
resonance energy of 14.4 keV in steps of 0.2 meV. The energy resolution of the X-ray beam was 1 meV. Debye
sound velocities (VD) were determined from the reduced
partial density of states (pDOS) using the “homogeneousmodel” described in Sinmyo et al. (2014). The densities required for the calculation of VD of bridgmanite were determined using a third-order Birch-Murnaghan equationof state based on volumes and elastic parameters reported
in Boffa Ballaran et al. (2012) (sample S4850) and Glazyrin
et al. (2014) (samples U1219, SL16, SL18, S4883), where
the generalized model in the latter work was used to calculate values relevant to the different compositions. Equations of state parameters for majorite were taken from
McCammon and Ross (2003) (cell volume) and Kavner etal. (2000) (elastic parameters). The adiabatic bulk modulus
can be used to calculate longitudinal wave (VP) and transverse wave (VS) velocities from VD and vice versa (e.g.,
Sturhahn and Jackson 2007).
First-principles calculations were performed based on
the local density approximation of DFT to determine the

DOS for MgSiO3 bridgmanite at 60 GPa and antiferromagnetic FeSiO3 bridgmanite at 20, 40, and 60 GPa. We
computed the dynamical matrices on a regular grid of
4 × 4 × 4 special q points (Monkhorst and Pack 1976).
We used Fourier interpolation techniques to obtain theinteratomic force constants on a dense grid in the reciprocal space, from which we obtained the phonon DOS(Gonze et al. 2005). We determined both the total andFig. 4 Influence of pressure on S4883 bridgmanite. a NIS spectra.
b pDOS (upper) and reduced pDOS (lower). The sample was loaded
as bridgmanite into the DAC, and data were collected oncompression during the same beamtime experimentMcCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 5 of 10

Fig. 5 Influence of pressure on S4850 bridgmanite. a NIS spectra. b pDOS (upper) and reduced pDOS (lower). The sample was loaded as
bridgmanite into the DAC, and data were collected during two different beamtime experiments: #1—50 GPa and #2—53 and 72 GPa. The
sample was laser-heated at 50 GPa, and data were collected both before and after laser heating

Fig. 6 Comparison of majorite and bridgmanite sample data at 0 GPa. a NIS spectra. b pDOS (upper) and reduced pDOS (lower). Majorite wasmeasured as the starting material in air while bridgmanite samples were measured after decompression

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 6 of 10

Table 2 Debye sound velocities at high pressure determined from NIS at room temperature and DFT at 0 K
Sample

Phase

P

VD

σVD

ρ

GPa

km/s

km/s

g/cm3

MethodRemarks
Starting material

U1219

Majorite

0

5.19

0.27

3.70

NIS

U1219

Majorite

33

5.45

0.62

4.29

NIS

U1219

Bridgmanite

0

3.56

0.46

4.31

NIS

U1219

Bridgmanite

33

5.51

0.59

4.78

NIS

U1219

Bridgmanite

41

5.80

0.66

4.87

NIS

U1219

Bridgmanite

49

6.27

0.88

4.97

NIS

U1219

Bridgmanite

62

5.62

0.55

5.11

NIS

U1219

Bridgmanite

74

6.79

1.15

5.23

NIS

U1219

Bridgmanite

89

7.23

1.17

5.37

NIS

SL16

Bridgmanite

0

3.53

0.05

4.25

NIS

Multianvil sample in air

SL18

Bridgmanite

0

3.21

0.12

4.24

NIS

After decompression

SL18

Bridgmanite

0

3.97

0.15

4.24

NIS

After decompression

SL18

Bridgmanite

17

4.45

0.31

4.50

NIS

SL18

Bridgmanite

36

5.72

0.38

4.74

NIS

SL18

Bridgmanite

50

6.84

1.62

4.90

NIS

SL18

Bridgmanite

62

5.95

0.31

5.03

NIS

SL18

Bridgmanite

65

6.65

1.16

5.06

NIS

SL18

Bridgmanite

75

6.47

1.15

5.16

NIS

S4850

Bridgmanite

0

3.81

0.12

4.43

NIS

After decompression

S4850

Bridgmanite

50

6.95

1.26

5.15

NIS

Before laser heating

S4850

Bridgmanite

50

6.35

1.39

5.15

NIS

After laser heating

S4850

Bridgmanite

53

5.54

0.47

5.19

NIS

S4850

Bridgmanite

72

6.14

0.69

5.40

NIS

S4883

Bridgmanite

17

5.03

0.72

4.52

NIS

S4883

Bridgmanite

55

5.11

0.53

4.99

NIS

After decompression

S4883

Bridgmanite

63

5.39

0.88

5.07

NIS

MgSiO3

Bridgmanite

60

8.21

0.32

5.03

DFT

From Mg partial DOS

FeSiO3

Bridgmanite

60

6.73

0.22

6.22

DFT

From Fe partial DOS

partial DOS for all the elements and calculated VD using
the same approach as for the experimental data. The
equation of state parameters were taken from Caracas
and Cohen (2005). We also determined seismic wave
velocities from the full elastic tensor where elastic constants were obtained from the linear relation between
stresses and strains. Uniaxial and/or pure shear strainson the order of ±1 % and ±2 % were applied, and thenthe positions of the atoms were relaxed. The elastic constants were determined from the residual stresses divided
by the strains. Voigt-Reuss-Hill schemes were employed
to average the elastic tensor, and seismic wave velocities
were determined based on homogeneous aggregates.

Results and discussion
We measured room temperature NIS spectra of one
majorite composition and five bridgmanite compositions

Fig. 7 Influence of pressure on VD for majorite. Values from thepresent study are indicated by large green circles, while literature
data are indicated by black symbols according to the legend

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Fig. 8 Influence of pressure on VD for bridgmanite. Experimental
values from the present study are indicated by large colored circles,
while Brillouin scattering data from the literature are indicated bysmall black triangles (Jackson et al. 2005) and small black circles(Murakami et al. 2007). Values from a previous computational
determination of the elastic tensor from finite differences (Caracas
and Cohen 2005) are indicated as red triangles for MgSiO3
bridgmanite and red squares for antiferromagnetic
FeSiO3 bridgmanite

as a function of pressure. In the case of majorite, sample
U1219 was first measured at 33 GPa and then laserheated to produce bridgmanite and measured again
without changing pressure. The NIS spectra show a clear
change between majorite and bridgmanite (Fig. 1a) that

Page 7 of 10

leads to different pDOS (Fig. 1b). Subsequent compressionof the U1219 bridgmanite sample produced systematicchanges in the NIS spectra (Fig. 2a) that are reflected in thepDOS (Fig. 2b). A similar behavior on compression was observed in bridgmanite with lower iron content (SL18, Fig. 3)
and Al-containing bridgmanite with lower (S4883) andhigher (S4850) amounts of Fe3+ (Figs. 4 and 5, respectively).
Finally, we collected data for the five different samples atambient conditions for comparison (Fig. 6).
Debye sound velocities (VD) were calculated fromthe reduced DOS in the limit as energy goes to zeroby averaging D(E)/E2 in the low-energy range as described in Sinmyo et al. (2014). VD values for majorite (Table 2) are slightly lower than the results
obtained for end-member MgSiO3 majorite and solid
solutions containing Fe and/or Al that were obtainedusing ultrasonics (Mg0.59Fe0.04Ca0.18Na0.03Al0.23Cr0.01Si0.90O3: Irifune et al. 2008; Mg0.875Al0.25Si0.875O3
and Mg0.85Al0.3Si0.85O3: Gwanmesia et al. 2009;
Mg0.95Al0.1Si0.95O3: Liu et al. 2015) and Brillouinscattering (MgSiO3 and Mg0.875Al0.25Si0.875O3: Sinogeikin and Bass 2002, Mg0.79Fe0.08Al0.30Si0.84O3: Murakami et al. 2008) (Fig. 7). These lower values are
consistent with the higher iron content of ourmajorite (Mg0.82Fe0.18SiO3). In contrast, the VD
values for bridgmanite (Table 2) are unrealistically
low compared to the results from Brillouin scattering(Fig. 8). We can rule out the influence of local clustering as a significant factor that lowers velocities

Fig. 9 DOS for MgSiO3 bridgmanite at 60 GPa calculated using DFT. The total DOS is shown in the upper left panel, while the pDOS are shown in
the other panels for the indicated element

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 8 of 10

Fig. 10 DOS for antiferromagnetic FeSiO3 bridgmanite at 60 GPa calculated using DFT. The total DOS is shown in the upper left panel, while thepDOS are shown in the other panels for the indicated element

since the effect is too small to account for the large
discrepancy (e.g., Sinmyo et al. 2014).
For a better understanding of the DOS for end-member
bridgmanite, we calculated the total DOS for MgSiO3
bridgmanite and antiferromagnetic FeSiO3 bridgmanite aswell as the pDOS for each element at 60 GPa (Figs. 9 and
10). For consistency with previous finite difference computations (Caracas and Cohen 2005), we calculated thefull elastic tensor to confirm that we obtained the sameelastic velocities within error. We then applied the same
approach used to obtain VD from the experimental DOS
obtained from NIS data to the theoretical DOS shown in
Figs. 9 and 10. We found that the VD values calculated
from each pDOS as well as the total DOS for each phasewere identical within error, i.e., the same result is obtained
irrespective of which element pDOS is used. In addition,
we found that the VD values calculated using this approach (Table 2) are consistent with values that we obtained from the full elastic tensor (8.23 and 6.78 km/s for
MgSiO3 and FeSiO3, respectively).
A Birch plot for bridgmanite data from both calculations and experiments highlights the anomalous
behavior of sound velocities determined using NIS(Fig. 11). To obtain further insight into the origin of
the low velocities of bridgmanite, we compare thepDOS for experiments and calculations. The breadthof vibrational states is smaller for bridgmanite calculated at 0 K compared to the experimental data at
room temperature, but it is similar for the experimental

data for both bridgmanite and majorite at room
temperature (Fig. 12, upper). In the reduced pDOS,
the enhanced intensity at low energies in the experimental bridgmanite data leads to a significantly higher
intercept and hence lower velocity compared to both
calculated bridgmanite and experimental majorite (Fig. 12,
lower). While particle size (e.g., Marquardt et al. 2011) oranisotropy (Chumakov et al. 2009) could be a factor, wenote that this effect is present in all the bridgmanite compositions that we measured using NIS, irrespective of sample synthesis method or history (i.e., whether they were

Fig. 11 Birch plot of VD versus density for bridgmanite. Symbols are
the same as for Fig. 8

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 9 of 10(3) Treatment of the DOS calculated using DFT for
MgSiO3 and FeSiO3 bridgmanite using the same
approach as for the NIS data gives soundvelocities that are consistent with each other foreach phase irrespective of which partial DOS is
used.
(4) Treatment of the DOS calculated using DFT
for MgSiO3 and FeSiO3 bridgmanite using
the same approach as for the NIS data gives
sound velocities that are consistent with thevalues obtained from the calculation of the fullelastic tensor.
(5)Comparison of the calculated and experimental DOS
shows enhanced intensity at low energies in thelatter that leads to the lower sound velocities.
Abbreviations
DAC: diamond anvil cell; DFT: density functional theory; DOS: density ofstates; NFS: nuclear forward scattering; NIS: nuclear inelastic scattering;pDOS: partial density of states.
Competing interests
The authors declare that they have no competing interests.

Fig. 12 Comparison of pDOS (upper) and reduced pDOS (lower)
determined by experiment and calculation. Experimental data arefrom the room temperature NIS spectra of S4850 bridgmanite at
53 GPa (red circles) and U1219 majorite at 33 GPa (blue line) while
the black line indicates DFT calculations of antiferromagnetic FeSiO3
bridgmanite at 60 GPa and 0 K

synthesized in the multianvil press or by laser heating in
the DAC). While it is clear from our results that sound velocities for bridgmanite determined using NIS cannot be
used for comparison with seismic data, there is clearlyscope for further work to identify the contributions
to the vibrational DOS derived from NIS data inorder to more fully understand the lattice vibrational
properties of bridgmanite.

Conclusions
Our work has presented an extensive dataset for bridgmanite with different compositions based on NIS measurements in a DAC as well as first-principles calculations:(1) NIS measurements of majorite give soundvelocities that are consistent with literature datafrom other methods, while NIS measurements ofbridgmanite give sound velocities that are
significantly lower than literature data.
(2) Sound velocities of bridgmanite determinedfrom NIS data are consistently low, irrespectiveof composition or sample history.

Authors’ contributions
CM, RC, and LD proposed the topic and conceived and designed the study.
The experimental data were collected by CM, KG, VP, AK, RS, CP, IK, AC, and
LD. CM, KG, CP, and AC analyzed the experimental data, and RC carried out
the ab initio calculations. All authors provided input to the interpretation of
the data and the writing of the manuscript. All authors read and approved
the final manuscript.
Acknowledgements
We acknowledge the European Synchrotron Radiation Facility for the provisionof synchrotron radiation facilities (ID18), and we would like to thank R Rüffer
and J-P Celse for additional assistance. The project was supported by funds
from the German Science Foundation (DFG) in their normal funding programand Priority Program SPP1236, the PROCOPE exchange program, and theGerman Federal Ministry for Education and Research (BMBF). RS was supported
by a Research Fellowship for Postdoctoral Researchers awarded by theAlexander von Humboldt Foundation.
Author details
1
Bayerisches Geoinstitut, Universität Bayreuth, Bayreuth 95440, Germany.
2
Laboratoire de Géologie de Lyon UMR CNRS 5276, Ecole Normale
Supérieure de Lyon, Lyon Cedex 07 69364, France. 3Deutsches
Elektronen-Synchrotron, Hamburg 22607, Germany. 4European Synchrotron
Radiation Facility, Grenoble Cedex 9 38043, France. 5National ResearchCenter “Kurchatov Institute”, Moscow 123182, Russia. 6ELSI, Tokyo Institute ofTechnology, Tokyo 152-8550, Japan. 7Institut für Geologie und Mineralogie,
Universität zu Köln, Köln 50969, Germany. 8Institut für Mineralogie, Universität
Münster, Münster 48149, Germany.
Received: 30 November 2015 Accepted: 19 April 2016

References
Birch F (1952) Elasticity and constitution of the Earth’s interior. J Geophys Res 57:
227–286
Boffa Ballaran T, Kurnosov A, Glazyrin K, Frost DJ, Merlini M, Hanfland M, Caracas
R (2012) Effect of chemistry on the compressibility of silicate perovskite in
the lower mantle. Earth Planet Sci Lett 333–334:181–190
Caracas R, Cohen RE (2005) Effect of chemistry on the stability and elasticity ofthe perovskite and post-perovskite phases in the MgSiO3-FeSiO3-Al2O3
system and implications for the lowermost mantle. Geophys Res Lett 32:
L16310. doi:10.1029/2005GL023164

McCammon et al. Progress in Earth and Planetary Science (2016) 3:10

Page 10 of 10

Chen B, Jackson JM, Sturhahn W, Zhang D, Zhao J, Wicks JK, Murphy CA (2012)
Spin crossover equation of state and sound velocities of (Mg0.65Fe0.35)O
ferropericlase to 140 GPa. J Geophys Res 117(B08208):2012. doi:10.1029/
2012JB009162
Chumakov AI, Bosak A, Rüffer R (2009) Contribution of acoustic modes to thedensity of vibrational states measured by inelastic scattering techniques.
Phys Rev B 90(094303):1–8
Crowhurst JC, Brown JM, Goncharov AF, Jacobsen SD (2008) Elasticity of (Mg,
Fe)O through the spin transition of iron in the lower mantle. Science 319:
451–453
Dubrovinsky L, Glazyrin K, McCammon C, Narygina O, Greenberg E, Übelhack S,
Chumakov AI, Pascarelli S, Prakapenka V, Bock J, Dubrovinskaia N (2009) Portablelaser-heating system for diamond anvil cells. J Synchrotron Radiat 16:737–741
Fiquet G, Badro J, Guyot F, Bellin C, Krisch M, Antonangeli D, Requardt H, Mermet
A, Farber D, Aracne-Ruddle C, Zhang J (2004) Application of inelastic X-ray
scattering to the measurements of acoustic wave velocities in geophysicalmaterials at very high pressure. Phys Earth Planet Int 143–144:5–18
Glazyrin K, Pourovskii LV, Dubrovinsky L, Narygina O, McCammon C, Hewener B,
Schünemann V, Wolny J, Muffler K, Chumakov AI, Crichton W, Hanfland M,
Prakapenka V, Tasnádi F, Ekholm M, Aichhorn M, Vildosola V, Ruban AV,
Katsnelson MI, Abrikosov IA (2013) Importance of correlation effects in hcp
iron revealed by a pressure-induced electronic topological transition. Phys
Rev Lett 110:117206
Glazyrin K, Boffa Ballaran T, Frost DJ, McCammon C, Kantor A, Merlini M, Hanfland
M, Dubrovinsky L (2014) Effect of iron oxidation state on the bulk soundvelocity of the Earth’s lower mantle. Earth Planet Sci Lett 393:182–186
Gonze X, Rignanese G-M, Caracas R (2005) First-principles studies of the latticedynamics of crystals, and related properties. Z Krist 220:458–472
Gwanmesia GD, Wang L, Triplett R, Liebermann RC (2009) Pressure andtemperature dependence of the elasticity of pyrope–majorite [Py60Mj40 and
Py50Mj50] garnets solid solution measured by ultrasonic interferometry
technique. Phys Earth Planet In 174:105–112
Irifune T, Higo Y, Inoue T, Kono Y, Ohfuji H, Funakoshi K (2008) Sound velocities
of majorite garnet and the composition of the mantle transition region.
Nature 451:814–817
Jackson JM, Zhang J, Shu J, Sinogeikin SV, Bass JD (2005) High-pressure soundvelocities and elasticity of aluminous MgSiO3 perovskite to 45 GPa:
implications for lateral heterogeneity in Earth’s lower mantle. Geophys Res
Lett 32, doi:10.1029/2005GL023522, 022005
Jackson JM, Hamecher EA, Sturhahn W (2009) Nuclear resonant X-ray
spectroscopy of (Mg, Fe)SiO3 orthoenstatites. Eur J Mineral 21:551–560
Kavner A, Sinogeikin SV, Jeanloz R, Bass JD (2000) Equation of state and strengthof natural majorite. J Geophys Res 105(B3):5963–5971
Keppler H, Frost DJ (2005) Introduction to minerals under extreme conditions. In:
Miletich R (ed) Mineral behaviour at extreme conditions, vol 7, EMU notes inmineralogy. Eötvös University Press, Budapest, pp 1–30
Kupenko I, Dubrovinsky L, Dubrovinkskaya N, McCammon C, Glazyrin K, Bykova E,
Boffa Ballaran T, Sinmyo R, Chumakov AI, Potapkin V, Kantor A, Rüffer R,
Hanfland M, Crichton W, Merlini M (2012) Portable double-sided laserheating system for energy-domain Mössbauer spectroscopy and single
crystal X-ray diffraction experiments at synchrotron facilities with diamondanvil cells. Rev Sci Instrum 83:124501
Lauterbach S (2000) Der Oxidationsgrad des Eisens im unteren Mantel: Eine
Studie des Fe3+-Gehaltes des Silikat-Perowskits in Abhängigkeit seines AlGehaltes mit Mössbauer-Spektroskopie und Elektronen-Energie-VerlustSpektroskopie (EELS). University of Bayreuth, Dissertation
Lauterbach S, McCammon CA, van Aken P, Langenhorst F, Seifert F (2000)
Mössbauer and ELNES spectroscopy of (Mg, Fe)(Si, Al)O3 perovskite: a highly
oxidised component of the lower mantle. Contrib Mineral Petrol 138:17–26
Lin J-F, Jacobsen SD, Sturhahn W, Jackson JM, Zhao J, Yoo C-S (2006) Soundvelocities of ferropericlase in the Earth’s lower mantle. Geophys Res Lett 33,
doi:10.1029/2006GL028099, 022006
Liu Z, Irifune T, Gréaux S, Arimoto T, Shinmei T, Higo Y (2015) Elastic wave
velocity of polycrystalline Mj80Py20 garnet to 21 GPa and 2,000 K. Phys
Chem Miner 42:213–222
Mao H-K, Xu J-A, Bell PM (1986) Calibration of the ruby pressure gauge to
800 kbar under quasi-hydrostatic conditions. J Geophys Res 91:4673–4676
Mao WL, Mao H-K, Sturhahn W, Zhao J, Prakapenka VB, Meng Y, Shu J, Fei Y,
Hemley RJ (2006) Iron-rich post-perovskite and the origin of ultralow-velocity
zones. Science 312:564–565

Marquardt H, Gleason A, Marquardt K, Speziale S, Miyagi L, Neusser G, Wenk H-R,
Jeanloz R (2011) Elastic properties of MgO nanocrystals and grain boundaries
at high pressures by Brillouin scattering. Phys Rev B 84(064131):1–9
McCammon CA, Ross NL (2003) Crystal chemistry of ferric iron in (Mg, Fe)(Si,
Al)O3 majorite with implications for the transition zone. Phys Chem Minerals
30:206–216
McCammon C, Kantor I, Narygina O, Rouquette J, Ponkratz U, Sergueev I,
Mezouar M, Prakapenka V, Dubrovinsky L (2008) Stable intermediate-spin
ferrous iron in lower mantle perovskite. Nat Geosci 1:684–687
McCammon C, Dubrovinsky L, Narygina O, Kantor I, Wu X, Glazyrin K, Sergueev I,
Chumakov A (2010) Low-spin Fe2+ in silicate perovskite and a possible layer
at the base of the lower mantle. Phys Earth Planet Int 180:215–221
McCammon C, Glazyrin K, Kantor A, Kantor I, Kupenko I, Narygina O, Potapkin V,
Prescher C, Sinmyo R, Chumakov A, Rüffer R, Sergueev I, Smirnov G,
Dubrovinsky L (2013) Iron spin state in silicate perovskite at conditions of the
Earth’s deep interior. High Pressure Res 33:663–672
Monkhorst HJ, Pack JD (1976) Special points for Brillouin-zone integrations. Phys
Rev B 13:5188–5192
Murakami M, Sinogeikin SV, Hellwig H, Bass JD, Li J (2007) Sound velocity of
MgSiO3 perovskite to Mbar pressure. Earth Planet Sci Lett 256:47–54
Murakami M, Sinogeikin SV, Litasov K, Ohtani E, Bass JD (2008) Single-crystal
elasticity of iron-bearing majorite to 26 GPa: implications for seismic velocity
structure of the mantle transition zone. Earth Planet Sci Lett 274:339–345
Potapkin V, McCammon C, Glazyrin K, Kantor A, Kupenko I, Prescher C, Sinmyo R,
Smirnov GV, Chumakov AI, Rüffer R, Dubrovinsky L (2013) Effect of ironoxidation state on the electrical conductivity of the Earth’s lower mantle. Nat
Commun 4(1427):1–6
Rüffer R, Chumakov AI (1996) Nuclear resonance beamline at ESRF. Hyperfine
Interact 97(98):589–604
Shukla G, Wu Z, Hsu H, Floris A, Cococcioni M, Wentzcovitch RM (2015)
Thermoelasticity of Fe2+-bearing bridgmanite. Geophys Res Lett 42:
1741–1749
Sinmyo R, Glazyrin K, McCammon C, Kupenko I, Kantor A, Potapkin V, Chumakov
AI, Rüffer R, Dubrovinsky L (2014) The influence of solid solution on elastic
wave velocity determination in (Mg, Fe)O using nuclear inelastic scattering.
Phys Earth Planet Int 229:16–23
Sinogeikin SV, Bass JD (2002) Elasticity of majorite and a majorite-pyrope solid
solution to high pressure: implications for the transition zone. Geophys Res
Lett 29:10.1029/2001GL013937
Stackhouse S (2008) The spin deep within. Nat Geosci 1:648–650
Sturhahn W, Jackson JM (2007) Geophysical applications of nuclear resonant
spectroscopy. In: Ohtani E (ed) Advances in high-pressure mineralogy, GSA
special paper 421. Geological Society of America, Boulder, pp 157–174
Townsend JP, Tsuchiya J, Bina CR, Jacobsen SD (2015) First-principles
investigation of hydrous post-perovskite. Phys Earth Planet In 244:42–48
Wang X, Tsuchiya T, Hase A (2015) Computational support for a pyrolitic lower
mantle containing ferric iron. Nat Geosci 8:556–559
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 37:L15304. doi:10.1029/2010GL043689

Submit your manuscript to ajournal and beneﬁt from:
7 Convenient online submission
7 Rigorous peer review
7 Immediate publication on acceptance
7 Open access: articles freely available online
7 High visibility within the ﬁeld
7 Retaining the copyright to your article

Submit your next manuscript at 7 springeropen.com