electron microscopy for multi-scale porous materials part...

Marseille Winter School on Multi-Scale Porous Materials (Jan 16-22 2014)

ELECTRON MICROSCOPY FOR MULTI-SCALE POROUS

MATERIALS

PART IV - AEM APPLICATIONS

J. BERTHONNEAU, O. GRAUBY & A. BARONNET

Outline

PART I

Clay mineralogy

Characterization methods

PART II - III (Alain BARONNET)

Basics of Transmission Electron Microscopy (TEM)

Preparation techniques

Applications to ultra structural clay mineral characterization

- physical aspects

PART IV

Analytical Electron Microscopy (TEM-EDX)

- chemical aspects

Applications to clay phases quantification

Crystal chemical characterization

Analytical Electron Microscopy

TEM

HRTEM

C * .

IMAGE

C *

0 0 1

0 0 2

0 0 3

c * c

b a

020

110

2 0 0

d(00l)

Clay minerals under TEM

IMAGE

Clay minerals under TEM

500 nm

Drop deposit Ultra thin section

Polytype 1M

Clay minerals under TEM

Chemical composition

EDX Energy Dispersive X-ray

EDS Energy Dispersive Spectroscopy

Electron / mater interactions

SAMPLE

Secondary e– (SEM)

Backscattered e– (SEM/EBSD)

Incident e–

Auger e–

X-rays fluorescence (EDX)

Elastically Scattered e– (ED)

Inelastically Scattered e– (EELS)

Unscattered e–

(transmitted beam)

Cathodoluminescence

Microprobe WDS Vs. TEM-EDX

Favor Kα excitation

300 keV

Sample

EDS

(h analys is)

X

1 µm

30 keV

Sample

Analysed

zone

Detector

(analys is)

X

5 µm

TEM-EDX is a satellite tool absolutely needed for mineralogical studies dealing with micro to nano size of crystals

Quantitative data for oxygen and

above Z > 16

X-ray energy 0-20 keV

V = 10 mm3

V = 10-6 mm3

Detector calibration

14001200100080060040020000,8

1,0

1,2

1,4

1,6

1,8

Calibration de K

(TOTAL COUPS)/s <-> EPAISSEUR

(CO

UP

S O

)/ (

CO

UP

S S

i)

O/Si1.679

Standart = Quartz SiO2

Silicates: Si = A

Standards: silicates (kaolinite, Talc, Wollastonite, etc.)

Raw measurement Extrapolation to t = 0

(counts = 0)

KO/Si = 2 / 1.679 = 1.191

If thickness => 0 If cA/cB known

Then: IB/IA = KB/A (cB/cA)

K-factor KB/A [Cliff & Lorimer, 1975] Spectrometer sensibility to element B with respect to a

reference element A (basically Silicon)

AEM results

TEM-EDX

ELEMENTS QUANTIFICATION

STRUCTURAL FORMULAS CALCULATION

Ternary diagrams allow

distinguishing the clay minerals :

[Meunier & Velde, 1989]

M+ = K + 2 x Ca + Na

4Si = Si / 4

R2+ = Mg

Analysis accuracy

Microprobe WDS:

(Si 3,93 Al 0,07) O10 (OH)2 Al 0,43 Fe 0,86 Mg 0,64 K 0,9

Bulk analysis Induced Coupled Plasma (ICP):

(Si 3,94 Al 0,06) O10 (OH)2 Al 0,39 Fe 3+0,65 Fe 2+

0,29 Mg 0,64 K 0,9

TEM-EDX + Mössbauer :

(Si 3,87 Al 0,13) O10 (OH)2 Al 0,38 Fe 3+0,55 Fe 2+

0,32 Mg 0,67 K 1

CELADONITE (BRAZIL)

Clay phase quantification

Attempt of localization

Applications

Multi-Scale approach

XRD (powder) Overall mineralogy

XRD (<4 µm) Clay identification

AEM (TEM-EDX) Particle chemistry

HR-TEM (PART II) Nano-texture and

structure

CLAY PHASE QUANTIFICATION

Step I: Identification (XRD)

Oriented mounts (<4 µm fraction) AD and EG

14,25 Å 7,11 Å 4,72 Å 3,54 Å

9,98 Å 4,98 Å

2:1:1 = chlorite

2:1 = mica

7,15 Å

17,2 Å 1:1 = kaolinite

Expandable layers ?

Step II: Crystal chemistry (AEM)

TEM-EDX

Step III: Profile modeling

Using ASN program [Sakharov & Drits, 1973; Ferrage, 2004]

Clay phase quantification

In the < 4 µm fraction:

And within the mixed-layer minerals:

Benefits of the approach

For profile modeling: For AEM results:

Multi-Scale approach

XRD (powder) Overall mineralogy

XRD (<4 µm) Clay identification

AEM (TEM-EDX) Particle chemistry

HR-TEM (PART II) Nano-texture and

structure

CLAY PHASE LOCALIZATION

Attempt of localization

OM

Precise Ion Polishing

System (PIPS)

1 mm

Ar+ Ar+

Attempt of localization

2

1

HR-TEM

TEM-EDX

Clay Phase Mapping (STEM-EDX) ?

Conclusions

Conclusions

Clay minerals display a multi-scale structure

Porosity: - Interlayer

- Interparticle

- Intergranular

Influence the physical properties of the deposit:

- Adsorption capacity

- Fluid (gas) transport

Electron microscopy locks up as an invaluable technique to work out their chemical and physical properties from the nanoscopic (HR-TEM) to the mesoscopic (TEM-EDX + XRD profile modeling) scale