SYNCHROTRON RADIATION IN THE EARTH SCIENCES

Simona QuartieriDipartimento di Scienze della Terra

Università di Messina

“The changes that have taken place in mineralogy in the last decade can besummarized as a shift in emphasistowards understanding the behaviour of minerals, that is, how they respond tothe chemical and physical changes duringthe geological processes.”

A. Putnis

“.... Earth scientists should be able to explain the few meter slip of San Andreas Fault during anearthquake on the basis of the breaking of chemicalbonds in silicate minerals. The excitement of modernEarth Sciences comes from this interplay of microscopic and macroscopic phenomena.”

A. Navrotsky

In the Earth Sciences SR can be used through two different approaches:

for applications of conventional techniques, already widely used in mineralogical investigations, but by which we intend, for instance, to study extremely small volumes, or to obtain better resolution, signal-to-noise ratio and detectability limits with respect to conventional sources;

as a unique radiation source, necessary for more innovative techniques such as XAFS spectroscopy on trace elements, DAFS spectroscopy, XAFS and X-ray diffraction under extreme P and T conditions, anomalous scattering, in-situ kinetic studies of phase transitions and synthesis reactions, X-ray fluorescence microanalysis with high spatial resolution and low detectability limits, X-ray topography and tomography

Campo energetico più utilizzato:– 4-70 KeV

Campo energetico interessante per gli elementi leggeri:

– 1-3 KeV

Principali tecniche basate sulla Principali tecniche basate sulla LdSLdS in uso in in uso in SdTSdTDiffrazione— a cristallo singolo

studi strutturali su cristalli estremamente piccolistudi strutturali in condizioni estreme

— su polveri “statica”caratterizzazione strutturale analisi qualitativa e quantitativa

— su polveri “in situ”cinetiche di sintesicinetiche di disidratazionetransizioni di fase in alta P e/o T

XAFSFluorescenza X; Spettroscopia IR

Zeolites are both very common minerals at the Earthsurface and important synthetic materials.

Much of interest in zeolites comes from theirindustrial application as catalysts and selectivesorbers.

These properties are related to the typical structureof zeolites, which consists of an aluminosilicateframework with cavities and channels of various size, which host cations and water molecules.

Terra Nova Bay Base

Na2.76K0.11Mg0.21Ca3.78Al11.20Si84.91O192 60H2O

Si/Al ratio = 7.6, the highest up to now found in natural zeolites

new pentasil zeolite with ZSM-5 topology

MUTINAITE

Crystal dimensions: 0.03 x 0.03 x 0.01 mm3

Single-crystal synchrotron X-ray diffraction

Crystal structure of the zeolite mutinaite, the natural analog of ZSM-5

Vezzalini et al. Zeolites, 19:323

MUTINAITEID11 (ESRF), detector: CCD camera

Intensities collected: 11548

Unique reflections: 5913

Reflections with I>5 σ (I): 3054

Rw: 8.86%

s.g. = Pnma

The high-temperature structures of zeolites are often studiedby conventional single-crystal diffraction performed at room T on crystals previously dehydrated in vacuum at selectedtemperatures and subsequently sealed in glass capillaries. This technique gives very detailed information on the structure of the dehydrated phases, but not on the dynamicsand kinetics of the process.

Alternatively, in-situ synchrotron X-ray powder diffraction isused for studying T-induced transformations and the outstanding quality of the powder data collected in this way can be used for full-profile Rietveld structural analysis.

The thermal behaviour of zeolites is widely investigated because of their potential use as molecular sieves and catalysts.

The thermal behaviour of zeolites is widely investigated because of their potential use as molecular sieves and catalysts.

Dehydration dynamics of zeolites using synchrotron X-ray powder diffraction

Dehydration dynamics of zeolites using synchrotron X-ray powder diffraction

Diffrazione da polveri in Diffrazione da polveri in LdSLdS• Sviluppo parallelo di stazioni sperimentali ad alta

risoluzione e di metodi di analisi degli spettri di diffrazione a profilo completo (es. metodo Rietveld)

larga diffusione della diffrattometria per polveri

• ottimo rapporto segnale/rumore• alta risoluzione dei picchi di diffrazione (FWHM

Beamline GILDA CRG (ESRF)

Sample heating: hot stream gas flowT range: 30 - 800°C, heating rate: 4-5°/minPowder samples in quartz capillary, sample spinning Detector: translating imaging plate

Capillary

HeaterGoniometric head

Experimental set up

heating gun

sample

lead screen

image plate

Esempio di

immagine raccolta

suImagePlate

Aumento della temperatura Traslazione dell’ImagePlate

FASE 1 FASE 2

FASE 3

Data analysis of the powder patternsFIT2D software

Rietveld method GSAS package

Dehydration of stelleriteCa8Al16Si56O144·58H2O

Arletti et al. (2005) Amer. Mineral.

Dehydration of stelleriteCa8Al16Si56O144·58H2O

Arletti et al. (2005) Amer. Mineral.

Experimental

• Powder spectra collected at Gilda beamline (ESRF)• Detector: translating image plate• Powder sample packed in a rotating capillary• T range = rT- 976 K (4K/min)

•Phase transition from Fmmm to Ammm•Statistical breaking of T-O-T bridges in the 4-rings and the migration of tetrahedral atoms to new “face-sharing” tetrahedra, which partially occlude the channels

Results

Stellerite Stilbite

Grossular schematic formula:

Ca3 Al2 Si3 O12

(Ca2.9 Mg0.06 Mn0.02 Na0.02.....) (Mg0.08 Ti0.89 Zr0.04 Al0.71 Fe3+0.28......) (Si2.33Fe3+0.62......) O12

Example of a real garnet formula:

MostMostMost mineralsmineralsminerals are are are solidsolidsolid solutionssolutionssolutions

MainMain crystalcrystal--chemicalchemical problemsproblems of of SOLID SOLUTIONSSOLID SOLUTIONS

• The structural relaxations associated with the elementsubstitution, which affect the stability of the solidsolution;

• the relationship between local structural deformationand the deviation from the ideal behaviour of the solidsolution;

• the location of minor and trace elements, which can explain• a) the element partitioning between cohexisting phases,• b) the modification of the technological properties of the

material.• the detection of order versus random distribution of

specific elements or clustering effects.

MineralogicalMineralogical applicationsapplications of XAFSof XAFS

• determination of cation local environment, oxidationstate, site distribution and short-range order;

• study of the distribution of major and minor elementsin glasses, silicatic melts and other disorderedsystems;

• determination of the local environment of minor and trace elements in complex matrices;

• high pressure and/or temperature investigations;• time resolved studies of transient phenomena by

dispersive EXAFS;• study of the static and dynamic disorder in geological

materials.

GARNETS GARNETS

GarnetsGarnets are a are a critical mineral phasecritical mineral phasefor the Earth upper mantle studies, for the Earth upper mantle studies, but are also but are also synthetic materials of synthetic materials of technologicaltechnological interestinterest

Most garnet solidMost garnet solid--solutionssolutions are not are not ideal,ideal, and longand long--range data on range data on pyropepyrope--grossulargrossular join indicate the presence join indicate the presence of of two two structure typesstructure types,, with an with an inversion point at inversion point at 50:5050:50

X

YZ

Pyrope Mg3Al2(SiO4)3Grossular Ca3Al2(SiO4)3Almandine Fe3Al2(SiO4)3

Spessartine Mn3Al2(SiO4)3Andradite Ca3Fe3+2(SiO4)3

Two possible approaches in the Two possible approaches in the study of a solid solution of study of a solid solution of

geological interest:geological interest:

Natural samples:Natural samples: already available in nature, already available in nature, but complex crystalbut complex crystal--chemistrychemistry

Synthetic samples:Synthetic samples: simple crystalsimple crystal--chemistrychemistrybutbut need for synthesis workneed for synthesis work

Incorporation of Sc in garnetsIncorporation of Sc in garnetsScSc is generally treated as an octahedral is generally treated as an octahedral cationcation, but , but in garnets it might partition itself among sites with in garnets it might partition itself among sites with different coordination.different coordination.

Syntheses performed in a piston cylinder apparatus, adding 5 wt% of Sc2O3 to the nominal mixtures, so that the incorporation site was not determined a priori.

Synthetic joinSynthetic join:: pyropepyrope--grossulargrossularMg3Al2(SiO4)3: prp,

prp60grs40,

prp20grs80,

Ca3Al2(SiO4)3: grs

Oberti, Quartieri, Dalconi, Iezzi, et al. (2005) American Mineralogist, submitted

Open questions:Open questions:

Does theDoes the site preferencesite preference of of dopantdopant Sc Sc change from change from pyropepyrope to to grossulargrossular? ? YES NOYES NO

Do theDo the intermediate compositionsintermediate compositions behave: behave: (i) like the prevalent end(i) like the prevalent end--member (i.e., member (i.e.,

two different structures along the join) two different structures along the join) (ii) like the weighted sum of the end(ii) like the weighted sum of the end--members members

(i.e., “mechanical mixing”)?(i.e., “mechanical mixing”)?

Is there anyIs there any clustering clustering yielding domains of yielding domains of pyropepyrope--like and like and grossulargrossular--like structures?like structures?

XANES ANALYSISXANES ANALYSIS

The spectral features ofThe spectral features ofpyropepyrope andand grossulargrossular are are very different, suggesting very different, suggesting different environmentsdifferent environments

TheThe solidsolid--solutionsolution terms are terms are more similar to the prevalent more similar to the prevalent endend--member, but show both member, but show both behavioursbehaviours

Experiments at theExperiments at the Sc KSc K--edgeedge donedone at theat the ondulatorondulatorbeamlinebeamline ID26 at ESFRID26 at ESFR

EXAFS ANALYSISEXAFS ANALYSIS

0

0.2

0.4

0.6

0.8

1

1.2

0 1 2 3 4 5 6

pyrfit

FT

R (Å)

Sc-SiSc-Mg

Sc-O

Sc-pyrope - multiple shells fit:

Pyrope:Sc at the X siteSc1-O = 2.17(2)Sc2-O = 2.31(2)

Sc

Sc-grossular: crystal-chemical indicationsfor a complex Sc distribution

Ca3 Al2Si3O12 : pure grossular end-member

Ca2.86 Al1.83 Si2.86 O12 : the composition of the major elements at the X, Y and Z sites in Sc-Grs

Ca2.86Sc0.14Al1.83Sc0.17Si2.86Sc0.14O12:

final crystal-chemical formula, with the total Sccontent distributed to complete the three sites. Confirmed by SC-XRD analysis

EXAFS ANALYSISEXAFS ANALYSISSc-grossular: a much more complex situation !

Simulated signal based on Sc occurring only at the Y site

Multi-shell fit based on the Sc distributionsuggested by crystal-chemical data

EXAFS RESULTSEXAFS RESULTS

X

Y

Z40% in Y

30% in X

30% in Z

Sc-grossular

Sc distributed over all garnetmatrix sites

K-edge XAFS characterization of the structural site of Nd, Ce and Dy in natural garnets

Example of direct crystallographic site Example of direct crystallographic site Example of direct crystallographic site assignment of trace elements assignment of trace elements assignment of trace elements

in few hundreds of in few hundreds of in few hundreds of ppmppmppm

A COMBINED APPROACH BASED ON THE FOLLOWING TECHNIQUES:

SIMS and electron microprobe analysis single-crystal X-ray diffraction high-energy XAFS spectroscopyfull multiple scattering calculations

Quartieri et al. (2002) Phys. Chem. Minerals 29, 495Quartieri et al. (2004) Phys.Chem. Minerals 31, 162

Sample compositionsNatural melanite garnets occurring in carbonatitic rocks:

A204: (Ca2.9Mg0.06Mn0.02Na0.02) (Mg0.08Ti0.89Zr0.04Al0.28Fe3+0.71) (Si2.33Fe3+0.62)

Nd =1125 ppm, Ce = 830 ppm, Dy = 299 ppm

V19: (Ca2.87Mg0.024Mn0.07Na0.04) (Mg0.06Ti0.82Zr0.03Al0.20Fe3+0.89) (Si2.45Fe3+0.49)

Nd = 349 ppm, Ce = 260 ppm

89/35: Ca3,01(Mg0.08 Mn0.03Ti0.44Zr0.01Al0.26Fe3+1.18)(Si2.70Fe3+0.29)

Nd = 176 ppm, Ce = 159 ppm

Nd (43569 eV), Ce (40443 eV) and Dy (53789 eV) K-edge spectracollected at 77K in fluorescence mode at the GILDA beamline

-0.05

0

0.05

0.1

0.15

0.2

2 4 6 8 10 12 14

Κχ(

Κ)

Κ ( )

Nd(OH)3

A204

V19

89/35

Å-1

Neodimium

176 ppm

349 ppm

1125 ppm

Neodimium: at the X site

DysprosiumDysprosium (299 (299 ppmppm): at the X site): at the X site

REE-O bond distances derived by XAFS, compared to those of Ca (by single-crystal XRD)

Ionic radii : Dy = 1.03, Nd = 1.109, Ce = 1.143, Ca = 1.12 Å

Garnet rX-O(1) σ2X-O(1) rX-O(2) σ2X-O(2)A204 (Å) (Å2) (Å) (Å2)

Nd 2.38(3) 0.006 2.47(3) 0.004

Ce 2.39(4) 0.004 2.51(4) 0.004

Dy 2.31(1) 0.003 2.41(3) 0.005

Ca 2.374(1) 2.523(1)REE-O bond distances consistent with the i.r. of the trace elements

strong crystal-chemical control on the partitioning of these elements among melt and coexisting mineralogical phases

XAFS STUDIES OF LIGHT ELEMENTSXAFS STUDIES OF LIGHT ELEMENTSXAFS STUDIES OF LIGHT ELEMENTS

TECHNICAL PROBLEMS:• In the range between 100 and 1500 eV the

number of available beamlines which allowgood XAFS measurements is limited (ELETTRA, Stanford, Lure, Wisconsin...)

• In the low energy region the absorption by air isan important effect, hence ultrahigh vacuumconditions are necessary

• Detection modes: total electron yield, fluorescence

Some HP Some HP Some HP mineralmineralmineral phasesphasesphases

Mg2SiO4 Ringwoodite

MgSiO3 MajoriteMg2SiO4 Beta-Phase

MgSiO3 Perovskite

Cation sites in Al-rich MgSiO3 perovskiteAndrault et al. Amer. Mineral. 83:1045

Cation sites in Al-rich MgSiO3 perovskiteAndrault et al. Amer. Mineral. 83:1045

MgSiO3 perovskite can acco-modate significant amount of Al3+:

Al3+ can enter only one of the perovskite sites and the chargebalance can be maintained viavacancies;

or Al3+ cations can substitute fora pair of Mg on the dodecahedralsite and Si on the octahedral site, maintaining the electroneutralitywithout vacancies.

Cation sites in Al-rich MgSiO3 perovskiteCation sites in Al-rich MgSiO3 perovskite

The local structure analysis of Al-containing silicateperovskite synthesized at 26 GPa and 1973 K in a multi-anvilapparatus has been performed by XAFS spectra recorded at Mg, Al and Si K-edges at SA32 beam-line of Super Aco (extra-situ study)

Comparisons were made with spectra of standard compounds and with theoretical multiple-scattering XAFS spectra calculated with FEFF 6.0.1 package.

ConclusionsAl appears to be partitioned between both octahedral

and dodecahedral perovskite sites.Fe2+ and Mg show a similar structural environment, i.e.

Fe2+ enters the dodecahedra of silicate perovskite.

ExtremeExtreme conditionsconditions

Indagini con Indagini con LdSLdS in condizioni estremein condizioni estreme

Gli esperimenti in altissime P e/o T permettono di studiare in situ le proprietà fisiche e strutturali delle fasi che si suppone siano presenti nel mantello inferiore e nel nucleo della Terra.

In questi studi si cerca di definire quali materiali abbiano le proprietà fisico-strutturali consistenti con osservazioni indipendenti di tipo geofisico e geochimico.

The diamond-anvil cell has emerged as the dominant and most versatile tool for achieving ultra-HP. It uses two diamond anvils, which exert pressure and serve as windows on the sample. A metal gasket confines the sample and supports the anvils.

DiamondDiamondDiamond anvilanvilanvil cellcellcell

Pressures higher than 100 GPa can be obtained onlyon micro-volumes of sample and hence synchrotronradiation is mandatory.

BirchBirch F. (1952) “F. (1952) “ElasticityElasticity and and constitutionconstitution of the of the Earth’Earth’s interior.” J. s interior.” J. GeophysGeophys. Res. 57:227. Res. 57:227--286 286

“Unwary readers should take warning that ordinary languageundergoes modifications to a high-pressure form when applied to the interior of the Earth; a few examples of equivalents follows:

High-Pressure: Ordinary meaning: certain dubious undoubtedly perhaps positive proof vague suggestion pure iron uncertain mixture of

elements

TheoriesTheories and and modelsmodels of the of the Earth’Earth’s interior s interior are are onlyonly asas goodgood asas the HP data behind the HP data behind themthem..

““UltrahighUltrahigh--pressurepressure mineralogymineralogy.”.” (1998) Reviews in Mineralogy Vol 37; R.J. Hemley Ed. “HighHigh--T and highT and high--P P crystalcrystal chemistrychemistry” (2000)

Reviews in Mineralogy Vol 41; Hazen and Downs Eds.

Acquisition of definitive high-pressure data dependsupon three basic pre-requisites:• reaching P-T conditions to study the stable phases• measuring material properties in situ at high P-T• achieving necessary accuracy

Synchrotron radiation is a perfect match for the study of the materials under extreme P and T: problems in HP mineralogy that were previously considered completely unapproachable can now being addressed.

In situ structure determinationof the high-P phase of Fe3O4

In situ structure determinationof the high-P phase of Fe3O4

• The high-P behaviour of Fe3O4 is studied because of its geophysicalimportance and interesting magnetic properties at high pressure.

• Experiments performed at ESRF, beamline ID30• powdered sample• Image plate detector • monochromatic (0.4253 Å ) synchrotron X-radiation• room s.g.: Fd3m• P/T conditions:

— 34.45 GPa, 300 K— 26.42 GPa, 723 K— 23.96 GPa, 823 K— 9.04 GPa, 923 K

• 23.96 GPa, 823K -phase structure— s.g. Pbcm (CaMn2O4-type structure)

Fei, Frost, Mao, Prewitt, Hausermann; Amer. Mineral. (1999) 84:203-206

High-P phase of Fe3O4 High-P phase of Fe3O4

23.96 GPa and 823K phases.g. Pbcm (CaMn2O4-type structure)The trivalent cations occupy the octahedral sites; the divalentcations occupy the 8-fold sites.This is one of the densest AB2O4structures.

Magnetite structurePart of Fe3+ cations occupy the tetrahedral sites; the Fe2+ and the remaining Fe3+ occupy the octahedral sites of the spinel structure

The observed two quadrupoledoublets for the high-P Fe3O4 phaseby Mossbauer data are consistentwith Fe3+ and Fe2+ occupying twodifferent crystallographic sites.

While magnetite is the best knownexample of ferrimagnetic material, the orthorhombic high-P phase isnot magnetically ordered on the basis of the Mossbauer results.

Then, the magnetic transition in Fe3O4, corresponding to the structural transformation, is best described by the change from the ferrimagnetic to the paramagneticstate.

SynchrotronSynchrotron InfraredInfrared MicrospectroscopyMicrospectroscopy

Vibrational IR spectra are particularly useful to:∗ elucidate changes in bonding properties;∗ allow identification of phase transitions;∗ provide information on crystal symmetry;∗ reveal directly lattice dynamical variables important

for calculating thermodynamic properties.

In particular, synchrotron IR microspectroscopy hasemerged as an important technique to studymicroscopic samples and is ideally suited to studygeological materials under extreme pressures, wheresample sizes are necessarily small.

Some Some applicationsapplications of of synchrotronsynchrotronIR IR spectroscopyspectroscopy toto geologicalgeological materialsmaterials

⇒In situ studies of phase transitions⇒OH content in microscopic inclusions in

diamond⇒trace hydrogen in nominally anhydrous

mantle phases⇒hydrogen at ultrahigh pressure⇒mineralogical composition of interplanetary

dust particles

Ruolo dell’ acqua nel mantelloRuolo dell’ acqua nel mantelloRuolo dell’ acqua nel mantelloL’interesse per la definizione del contenuto di idrogeno nel mantello e nel core terrestri è dovuto alle importanti implicazioni che esso ha su:

a) proprietà di trasporto nei mineralib) sui processi di formazione dei fusic) sulla evoluzione dell’atmosfera e degli oceani

garnetkyanite

olivine

enstatite

zircone

omphacite

TraceTrace hydrogenhydrogenin in nominallynominally anhydrousanhydrous mantlemantle phasesphases

The trace hydrous species can have a disproportionately large influence on the chemical, mechanical, electronic and physical properties of the mineral.

The uptake of hydrogen in MgSiO3 perovskite, the most abundant mineral in the planet, was examined. Although nominally anhydrous, the synchrotron measurements revealed that the material can accommodate a surprising amount of hydrogen such that a significant fraction of the water in the current oceans could be stored in the lower mantle.

SynchrotronSynchrotron Infrared Absorbance Measurements Infrared Absorbance Measurements of of hydrogenhydrogen in MgSiOin MgSiO33 PerovskitePerovskite

Micro-IRmeasurements show two hydroxylabsorbance peaks at 3483 and 3423 cm-1

MeadeMeade etet al.al. (1994) (1994) ScienceScience, 264:1558, 264:1558

The frequency of the absorption peak indicates that there is a weak hydrogen bonding in the perovskitecrystals and that the proton is positioned between two oxygen atoms that are spaced about 2.75 Åapart, that is between oxygens on adjacent octahedrons that are tilted toward each other in the 001, 110 and -110 planes.

The estimated trace hydrogen content, when integrated over the lower mantle volume, corresponds to a concentration comparable to 12% of the mass of hydrogen in the Earth’s hydrosphere.

Future studies to determine the maximum hydrogen concentrations in perovskites synthesized over a range of compositions are needed for assessing the importance of nominally anhydrous phases as repositories of the Earth’s hydrogen.

If the hydrogen content of perovskite is as variable as that of low-pressure silicates, the hydrogen content of the lower mantle perovskite could exceed that of the hydrosphere.

Synchrotron IR spectroscopy of synthetic P21/m amphiboles at HP and HP

(Iezzi et al. 2005 a,b)

Taking into account the widespread presence of amphiboles in subduction zone, it is important to understand their behaviour at depths within the Earth (HT and HP), as a function of their compositions

How and which are the structures of amphiboles inside

the Earth?

Synchrotron IR spectroscopy of synthetic P21/m amphiboles at HP

(Iezzi et al. 2005)

Na(Na0.6Li0.4Mg)Mg5Si8O22(OH)2 (sample 405) P21/m at room T

HIGH-P FTIR OH-stretching spectra (3000-4000 cm-1) have been collected at the U2A beamline, VUV ring of the National Synchrotron Light Source, Brookhaven NY, USA. The fine amphibole powder was loaded into a symmetric diamond anvil cells (DAC) together with some ruby chips as pressure gauge. A Bruker IFS 66v/S vacuum Fourier transform interferometer, with a Bruker IRscope II microscope equipped with a HgCdTe type-A detector was used.

Optical Layout of the Infrared Synchrotron U2A Beamline

Bruker IFS66v/sFTIR Spectrometer

M2M1

Detector

VacuumBench

N2 purgedBruker IRscope II

Diamond cell in the cryostat

NSLSVUV

Ø10mmdiamondwindow

Vacuum box

Vacuumpipe

VacuumMicroscope

MCT DetectorBolometer

DACMCT Detector

KBr window

Ø10mmdiamondwindow

Diamond lens

FS

FS

N2 purged Low-TFar/Mid-IR MICROSCOPE

MCT 1

MCT 2

Bolometer

Laser FS Microscope 2

Microscope 1

Microscope 3

Visible spectrograph

CCD detector

eyepiece • Near IR through far IR spectral range• Reflectivity and absorption

measurements• Low-temperature measurements• Mapping of the samples• In situ Raman and fluorescence

measurements• diamond lens

U2A beamline optical hutch

notch filters

1 atm

wavwnumbers (cm-1)

36403660368037003720374037603780380038203840386038803900

1.4

4.1

6.9

8

9.4

11.6

15.1

18.6

arbi

trary

uni

ts

21.8

23.2

27.7

31.2

36403660368037003720374037603780380038203840386038803900

P SA M PLE 405

1.42 G Pa

4.13 G P a 6.94 G Pa

7.97 G P a

9.35 G P a11.59 G Pa

15.08 G Pa18.6 G pa

21.79 G Pa23.22 G Pa

27.73 G Pa31.18 G P a

3600 3700 3800 3900

1 atm R om e

3600 3700 3800 3900

25 G P a b

16.48 G P a b

10.81 G P ab

6.09 G P a b

1.50 G Pa b

0.66 G P a b

P

The two main bands present in the low-P spectra merge into a unique symmetrical band at high pressure

Completely reversible transformation

The appearance at high-P of a single IR OH-symmetric stretching band suggests the presence of a unique O–H bond

Pnma and P21/m structures have two symmetrically independent tetrahedral chains, determining also two O-H bonds; C2/m amphiboles has a unique type of tetrahedral chains and a unique O-H bond type

HP-induced phase transition

to C2/m s.g.

The same phase transition is observed at HT, at different temperaturesdepending on the amphibole composition

+250°C

-180°C

C2/m

P21/m

The OH and OD spectra obtained at 300 and 20 K are very similar, in agreement with the fact that both samples have the samesymmetry

Aim: to investigate the possibleexistence of a low-T (rT-8K) phasetransition form P21/m to C2/m

Results: both neutron diffraction(presence of reflections with h+k= 2n+1) and FTIR data confirm that the lattice remains primitive

AngleAngle--dispersivedispersive XRD XRD spectraspectra (SPring(SPring--8)8)

Pbnm perovskite

Cmcm post- perovskite

Layer-stackingstructure

Since iron is the dominant component of Earth’s core, information on its behavior at high-T and high-P is necessary to understand the structure of the core, the chemical and dynamical coupling betweencore and mantle, and Earth’s magnetic field.

CORE CORE CORE ironironiron

FCC

HCP

BCC

The orthorhombic structure of iron: an in situ study at high-T and high-P

Andrault et al., Amer Mineral. (2000) 85:364

The orthorhombic structure of iron: an in situ study at high-T and high-P

Andrault et al., Amer Mineral. (2000) 85:364

• In situ angle-dispersive X-ray diffraction study in a laser-heated, diamond-anvil cell up to 2375 K and between 30 and 100 GPa.

• RESULTS: at high-T and P iron undergoes a phasetransformation to an orthorhombic lattice with s.g. Pbcm

Quenchedphase

β-Fe

ε-Fe

ε-Fe

β-Fe

γ-Fe

XX--rayray FluorescenceFluorescence MicroanalysisMicroanalysisLa microsonda a raggi X da luce di sincrotrone consente di coniugare la diffusissima tecnica di analisi per fluorescenza-X, divenuta tra le piu’comuni tecniche di quantificazione chimica elementare nelle scienze geologiche, con la possibilita’ di mantenere un’elevata risoluzione spaziale nel volume di campione analizzato, tipica della microsonda elettronica.

XX--rayray FluorescenceFluorescence MicroanalysisMicroanalysis

VANTAGGI:—e’ un metodo non distruttivo—ha un limite di rivelabilità inferiore a 0.1-5 ppm per gli elementi con

Z maggiore di quello del K, ed è molto inferiore a quello della microsonda elettronica in virtù dell’elevatissimo rapporto segnale/rumore

—ha una risoluzione spaziale dell’ordine di 10µm

ESEMPI DI APPLICAZIONI:—analisi dei componenti in traccia in minerali, anche su piccoli

volumi (

XX--rayray FluorescenceFluorescence MicroanalysisMicroanalysis++

micromicro--XANESXANES

Un’ interessante combinazione sperimentale è rappresentata dall’utilizzo combinato di micro-fluorescenza a raggi X in LdS e micro-XANES, per esempio per ricavare mappe bidimensionali dei gradienti di ossidazione sul campione o per vedere la variazione spaziale della concentrazione degli elementi di interesse nel composto in funzione dello stato di ossidazione.

Analysis of a 100 µm zircon, in which a pure quartz inclusion, approximately 7 µm x 3.5 µm in size, is identified and mapped with sub-micrometer resolution, at the SiL2,3 edge. (Gilbert et al. (2003) Amer. Mineral.)

Iron in Martian Meteorites: Microanalyses of Fe3+/ΣFe by Synchrotron MicroXANES

as Indicators of Variable Oxygen FugacityJ.S. Delaney, S.R. Sutton and M.D. Dyar

The results for the Martian suite are consistent withthe formation of these rocks in a very “terrestrial”, i.e. oxidized, setting: the range of Fe3+/ΣFe seen iscomparable to that found in many mantle and eruptive rocks on Earth.

Martian samples are much more oxidized thanlunar, basaltic achondrite and most chondriticmeteorites.

Chemical Analysis of Impact Material on a Dust Collector Flown on the MIR Space Station

G. J. Flynn (SUNY-Plattsburgh) S. R. Sutton (The University of Chicago) F. Horz (NASA Johnson Space Center)

Sub-micrometer scale minor element mapping in interplanetary dust particle:

a test for stratospheric contaminationFlynn et al. Lunar and Planetary Science XXXV (2004)

S Ca Cr

Fe Ni Zn

Applications of Synchrotron Radiation in

Low-Temperature Geochemistryand Environmental Science

Review in Mineralogy and Geochemistry, Vol. 49 (2002)Editors: P. Fenter, M. Rivers, N. Sturchio, S. Sutton.

Changes in the bond distances for differentX-site cations in different garnet compositions

Squares = Quartieri et al (PCM 2002; PCM 2004); diamonds = Euler and Bruce (1965); triangles = Quartieri et al (PCM 1999).

The observed different slopes show that the structural relaxation around the dopant strongly depends on the overall garnet composition and that the X site has a different compliance for solid solution in the various garnet compositions

Tektites are naturally occurring glasses which are found, after an impact event, scattered over wide areas called strewn fields. Tektites are virtually crystal-free so that it is not possible to reconstruct their T-P history directly from phase stability considerations.

However, glass structural properties, such as coordination number of its constituting elements, depend on their composition and P-T history.

Pressure tends to increase the mean coordination number of the cations present which, in turn, directly affects glass properties such as density and viscosity. Thus, the knowledge of the glass structure of tektites could help to constrain the P-T conditions of formation.

EXPERIMENTALS XANES spectra were collected at the beamline SB03-3 of the SPEAR storage ring (SSRL, Stanford, U.S.A.) operating at 3 GeV with ring current ranging from 65 to 90 mA. Radiation was monochromatized by two YB66 (400) crystals (2d = 5.88 Å)

Tektite spectra clearly resemble the spectrum of albite. Both display a single and narrow peak A; the energies of the absorption edge are similar, as are the energy positions of the features A, B and the large peak at the high energy side (peak C of tektite spectra and peak D and E of the albitespectrum). These data indicate that Al is fourfold-coordinated in all the six tektites studied.

GARNET STRUCTUREGARNET STRUCTURE

X site: [4+4]X site: [4+4]--foldfold coordinationcoordination

prpprp: 2.270 Å,: 2.270 Å, S

LONG-RANGE EVIDENCES FOR NON-IDEALITY OF GARNET SOLID-SOLUTIONS

UnitUnit--cellcell edgeedge (Å)(Å) UnitUnit--cellcell edgeedge (Å)(Å)a vs. S(Y)-U(Y)

-0.08-0.07-0.06-0.05-0.04-0.03-0.02-0.010.000.010.020.030.040.050.060.070.080.090.100.11

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

adi

ffer

enza

spi

golo

Y (Å

)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

S( Y

) S(

Y ) --

U(Y

)U(Y

)

prpprp grsgrs adradr

a vs. delta X-O

0.135

0.140

0.145

0.150

0.155

0.160

0.165

0.170

0.175

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

delta

X-O

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

(X1

(X1 --

O)

O) --

(X2

(X2 --

O)

O)

a vs. rotaz T

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

rota

z. T

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

Z r

otat

ion

Z ro

tation

a vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradr

prpprp grsgrs adradr

prpprp grsgrs adradr

UnitUnit--cellcell edgeedge (Å)(Å) UnitUnit--cellcell edgeedge (Å)(Å)a vs. S(Y)-U(Y)

-0.08-0.07-0.06-0.05-0.04-0.03-0.02-0.010.000.010.020.030.040.050.060.070.080.090.100.11

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

adi

ffer

enza

spi

golo

Y (Å

)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

S( Y

) S(

Y ) --

U(Y

)U(Y

)

prpprp grsgrs adradr

a vs. delta X-O

0.135

0.140

0.145

0.150

0.155

0.160

0.165

0.170

0.175

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

delta

X-O

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

(X1

(X1 --

O)

O) --

(X2

(X2 --

O)

O)

a vs. rotaz T

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

rota

z. T

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

Z r

otat

ion

Z ro

tation

a vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradr

prpprp grsgrs adradr

prpprp grsgrs adradr

a vs. S(Y)-U(Y)

-0.08-0.07-0.06-0.05-0.04-0.03-0.02-0.010.000.010.020.030.040.050.060.070.080.090.100.11

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

adi

ffer

enza

spi

golo

Y (Å

)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

S( Y

) S(

Y ) --

U(Y

)U(Y

)

prpprp grsgrs adradrprpprp grsgrs adradr

a vs. delta X-O

0.135

0.140

0.145

0.150

0.155

0.160

0.165

0.170

0.175

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

delta

X-O

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

(X1

(X1 --

O)

O) --

(X2

(X2 --

O)

O)

a vs. rotaz T

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

rota

z. T

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

Z r

otat

ion

Z ro

tation

a vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradr

prpprp grsgrs adradr

prpprp grsgrs adradra vs. delta X-O

0.135

0.140

0.145

0.150

0.155

0.160

0.165

0.170

0.175

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

delta

X-O

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

(X1

(X1 --

O)

O) --

(X2

(X2 --

O)

O)

a vs. rotaz T

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

rota

z. T

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

Z r

otat

ion

Z ro

tation

a vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradr

prpprp grsgrs adradra vs. rotaz T

24.0

24.5

25.0

25.5

26.0

26.5

27.0

27.5

28.0

28.5

11.40

11.45

11.50

11.55

11.60

11.65

11.70

11.75

11.80

11.85

11.90

11.95

12.00

12.05

12.10

12.15

12.20

a

rota

z. T

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+Nb

Z r

otat

ion

Z ro

tation

a vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradra vs. spigoli X

2,65

2,70

2,75

2,80

2,85

2,90

2,95

3,00

3,05

11,40

11,45

11,50

11,55

11,60

11,65

11,70

11,75

11,80

11,85

11,90

11,95

12,00

12,05

12,10

12,15

12,20

a

spig

oli X

(Å)

rosso gar +Scblu gar + Tiverde gar + Zr+ rosso gar Na+NbS(X)S(X)

U(X)U(X)

prpprp grsgrs adradrprpprp grsgrs adradr

prpprp grsgrs adradrprpprp grsgrs adradr

prpprp grsgrs adradrprpprp grsgrs adradr

Crystallographic Data Base at CNR, Istituto di Geoscienze e Georisorse, Pavia (I)

Mineral descriptions based on averaged partial occupancies and random distributions of different species often fail spectacularly

Information on the local environment and properties has proven to be crucial

In the Earth Sciences SR can be used through two different approaches:Principali tecniche basate sulla LdS in uso in SdTTerra Nova Bay BaseCrystal structure of the zeolite mutinaite, the natural analog of ZSM-5Vezzalini et al. Zeolites, 19:323MUTINAITEDiffrazione da polveri in LdSExperimental set upDehydration of stelleriteCa8Al16Si56O144·58H2OArletti et al. (2005) Amer. Mineral.StelleriteMain crystal-chemical problems of SOLID SOLUTIONSMineralogical applications of XAFSOpen questions:XANES ANALYSISEXAFS ANALYSISSc-grossular: crystal-chemical indications for a complex Sc distributionEXAFS ANALYSISEXAFS RESULTSK-edge XAFS characterization of the structural site of Nd, Ce and Dy in natural garnetsSample compositionsNd (43569 eV), Ce (40443 eV) and Dy (53789 eV) K-edge spectra collected at 77K in fluorescence mode at the GXAFS STUDIES OF LIGHT ELEMENTSCation sites in Al-rich MgSiO3 perovskiteAndrault et al. Amer. Mineral. 83:1045Cation sites in Al-rich MgSiO3 perovskiteIndagini con LdS in condizioni estremeBirch F. (1952) “Elasticity and constitution of the Earth’s interior.” J. Geophys. Res. 57:227-286“Ultrahigh-pressure mineralogy.” (1998) Reviews in Mineralogy Vol 37; R.J. HemIn situ structure determination of the high-P phase of Fe3O4High-P phase of Fe3O4Synchrotron Infrared MicrospectroscopySome applications of synchrotron IR spectroscopy to geological materialsTrace hydrogen in nominally anhydrous mantle phasesSynchrotron Infrared Absorbance Measurements of hydrogen in MgSiO3 PerovskiteThe orthorhombic structure of iron: an in situ study at high-T and high-P Andrault et al., Amer Mineral. (2000) 85:364X-ray Fluorescence MicroanalysisLa microsonda a raggi X da luce di sincrotrone consente di coniugare la diffusissima tecnX-ray Fluorescence MicroanalysisChemical Analysis of Impact Material on a Dust Collector Flown on the MIR Space StationG. J. Flynn (SUNY-PSub-micrometer scale minor element mapping in interplanetary dust particle: a test for sApplications of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental SciChanges in the bond distances for different X-site cations in different garnet compositionsLONG-RANGE EVIDENCES FOR NON-IDEALITY OF GARNET SOLID-SOLUTIONS