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(Electron) microscopy at MTM

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Presentation on theme: "(Electron) microscopy at MTM"— Presentation transcript:

1 (Electron) microscopy at MTM
SIM² workshop HiTemp group – MTM Annelies Malfliet 23 January 2013

2 Content Microscopy at MTM: in general Sample preparation In particular
SEM XL30 FEG/XL40 LAB6 FEG-EPMA JXA-8530F TEM CM 200 FEG FEI Nova NanoSEM Contact details 23/01/2013

3 Microscopy at MTM 23/01/2013

4 Overview microscopy https://www.mtm.kuleuven.be/English/Research/Equipment/List#_Microscopy New µscope FEI Nova NanoSEM 23/01/2013

5 Core facility ‘Electron microscopy’
State-of-the-art Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) 23/01/2013

6 (Electron) microscopy’
Imaging: phase distribution, particle size, topography, ... Light Optical Microscopy (LOM) Secondary Electron (SE) or Backscattered Electron (BSE) imaging (on SEM) Bright-Field (BF) imaging (on TEM) Chemical analysis: phase composition, presence of impurity elements, element distribution, ... Energy Dispersive Spectroscopy (EDS) (on SEM/TEM) Wavelength Dispersive Spectroscopy (WDS) (on FEG-EPMA) Electron Energy Loss Spectroscopy (EELS) (on TEM) Crystallography: crystal structure + texture Electron Backscatterd Diffraction (EBSD) (on SEM) Selected Area Electron Diffraction (SAED) or Convergent Beam Electron Diffraction (CBED) (on TEM)  Broad spectrum of equipment and preparation facilities 23/01/2013

7 Electron microscopy Difference LOM – EM Resolution
Source: light vs. electrons Optical lenses vs. eletromagnetic lenses Eye vs. Detectors Resolution Most used electron microscope is Scanning Electron Microscope (SEM) 23/01/2013

8 SEM detectors Typical detectors
Secondary electron detector (SE) Good spatial resolution Topography Backscattered electron detector (BSE) Strong atomic number contrast X-ray detector Elemental analysis Different signals originate from different interaction volumes Effect of voltage on interaction volume 23/01/2013

9 Composition analysis Based on emission of characteristic X-rays caused by excitation from eletron beam X-ray can be detected by: Energy Dispersive Spectroscopy X-ray are separated based on their energy Result is an energy-intensity spectron with peaks Peak position identifies the element Height ~ its concentration (standardless quantification) Energy resolution ~127eV Measuring time: s (all elements measured at the same time) Wavelength Dispersive Spectroscopy not on SEM, but on Electron Probe Micro Analysis (EPMA) Higher spectral resolution Typically quantification with standards More time consuming (5 spectrometers  up to 5 elements measured at the same time) 23/01/2013

10 SEM - TEM Difference SEM – TEM
Higher eV with TEM  beam with smaller wavelength  higher spatial resolution Observe electrons passed through (and interacted with) the sample Much smaller and especially thinner sample electron source D = 3 mm sample screen 23/01/2013

11 Crystal structure/texture
Overview table Imaging Phase composition Crystal structure/texture EDS WDS EELS Light optical microscopy x XL40 SEM LAB6 XL 30 SEM FEG XL30 ESEM FEG XL30 SEM + EBSD FEI Nova Nanosem JXA-8530F FEG-EPMA TEM CM 200 FEG 23/01/2013

12 Effort - information Microscopy technique is mainly determined by
What information you would like to have Size of the features of interest Depending on technique, material and required sample ‘perfectness’, the parameters that determine effort are: Sample preparation Embedding: 15 min – 1 day curing/ conductive resin (under pressure) Grinding/polishing: hard/brittle/porous/soluble in water(ethanol)/... Conductive coating needed: thickness, homogeneity Preventing contamination (air, moisture): storing in desiccator/vacuum/cryo cleaner/... Removing contamination: plasma cleaner/... Learning process Training Experience/practice! Literature reading 23/01/2013

13 Effort - information map
In general ... 23/01/2013

14 Sample preparation 23/01/2013

15 Sample preparation at MTM
https://www.mtm.kuleuven.be/English/Research/Equipment/List#_Sample_preparation 23/01/2013

16 Sample preparation In general: for LOM/SEM/EBSD (room 02.33) Cutting
grinding In general: for LOM/SEM/EBSD (room 02.33) Cutting Ultrasonic cleaning: remove particles from pores Embedding with Technovit: cures very fast (15 min) Epofix: better infiltrates pores  better for powder or porous material (1 day curing under vacuum) Predopress (pressure/hot mounting): harder resin  better for harder materials (also conductive powder available for conductive resin  no need for coating in case of conductive sample) Grinding/polishing/OPS Manual or automatic Cooling + removing debris: water/ethanol/oil OPS: soft/ductile materials Different materials require different grinding + polishing procedure  best to talk with responsible technician polishing 23/01/2013

17 Sample preparation Especially for evaluation of interfaces or for soft material: Cross section ion polishing Clean surface on large area (~ 1 mm²) Disadvantage: more time consuming than mechanical polishing Au Ni-P Cu CP method Polishing time: 4 hours Mechanical polishing 23/01/2013

18 Sample preparation Etching (for metals)
In acid, electrolytically Coating with C/Au/Pt/Au-Pd/Pt-Pd Au-Pd: imaging surface topography/gives higher resolution C: Chemical analysis, mapping, EBSD Carbon rod: better suited for thin homogeneous layer than carbon wire For EDS/WDS: Pay attention to overlap of peaks of coating and sample Degassing in vacuum chamber Coating units at MTM 23/01/2013

19 Sample preparation TEM: more complicated + different methods depending on material Separate TEM sample preparation room at MTM Possible at MTM Thin film: grinding/polishing/thinning/breakthrough (electrolytic,ion miller) Replica method Depositing on support grid Ultramicrotome to cut slices FIB ... 23/01/2013

20 SEM XL30 FEG/XL40 LaB6 23/01/2013

21 SEM XL30 FEG Equipment details Most frequent used EM
kV SE/BSE detector EDS (detection from B) Most frequent used EM User-friendly Many users 1 day training Reservation per 2 hour 1-3 samples Many users  highly occupied (24h/d; 7d/w) Alternative is SEM XL40 LaB6: similar possibilities (SE/BSE, EDS, ...) Particle analysis software LaB6 vs. FEG: LaB6 has larger probe diameter and less brightness, but for many applications it can be sufficient Almost not used XL30: BSE image + EDS analysis XL40: BSE image 23/01/2013

22 FEG-EPMA 23/01/2013

23 FEG-EPMA JEOL JXA 8530F 23/01/2013

24 Main features In-Lens Schottky Field Emission Gun (FEG) Imaging
kV, 50 pA – 500 nA, 40 nm minimum probe size Imaging Electron detectors: SE + BSE 40x to 300,000x magnification Cathodeluminescence system Monochromatic + panchromatic Phase composition EDS system: Resolution: 129 MnKa WDS system: 5 full scanner type X-ray spectrometers 23/01/2013

25 FEG-EPMA: Use Typical analysis type 0.5-1 day/sample 3-day training
Composition quantification using standards Including minor and light elements Mapping elemental distribution Better spectral resolution  oxidation state of elements 0.5-1 day/sample Possible to let it run overnight by setting measurement points or mapping area 3-day training Users are through promotors of the FEG-EPMA For external and occasional measurements, technical responsible at MTM can do the measurement 23/01/2013

26 Transmission Electron microscopy (TEM)
23/01/2013

27 TEM CM 200 FEG Details Few users Several day training 20-200 kV
Resolution < nm EDS/EELS GATAN Tridiem Image Filter Few users Several day training 23/01/2013

28 TEM: Use Characterization of nanoscale particles with respect to their shape, size, structure, chemical composition and distribution. Imaging Diffraction: crystal structure Composition analysis EDS EELS: especially useful for light elements 23/01/2013

29 FEI Nova NANOSEM 23/01/2013

30 FEI Nova Nanosem FEI Nova Nanosem
Imaging (SEM with TLD) High resolution Low keV imaging ‘Pure’ samples (not coated) Difficult samples (magnetic, non-conductive) Chemical analysis (EDS) Phase/ texture analysis (EBSD) Chrystallographic characterisation Integration with EDS  phase analysis Plasmacleaner Just installed, about to be operational Anodized Ti EDS+EBSD 23/01/2013

31 What if you would like to use one of the microscopes at MTM?
23/01/2013

32 Contact details For more information:
Core facility Electron microscopy: Tom Van der Donck SEM XL30/XL40: Rudy De Vos If you are advised to have a training, use the training request form available at https://ppms.info/kuleuven/treq/?pf=2 23/01/2013


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