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