Research and facilities in electron microscopy

at the Department of Chemical Engineering and Geosciences

Johanne Mouzon, Jonas Hedlund, Pär Weiheid

OutlineIntroduction

I. Magellan 400: extreme high-resolution SEM

II. Merlin: SEM for nanoanalytics

Conclusion

Introduction

SEM facilities at LTU before 2009• Department of Chemical Engineering and Geosciences:

Philips XL-30: LaB6 filament, 14 years old, old EDS outmoded, limited resolution

• Department of Applied Physics and Mechanical Engineering:

Jeol JSM 6460lv: W/LaB6 filament, 7 years old, EDS/WDS, EBSD, low vacuum, cryogenic/heating stage, stage for tensile testing flexible/all-round, limited resolution, current too unstable for good WDS

•Strong need for a modern high resolution (HR-SEM) instrument and an analytical tool (type microprobe) for accurate elemental analysis in numerous research areas at the university.

Application to The Knut and Alice Wallenberg Foundation

Application for a HR-SEM instrument

Applicants•Professor Kris Berglund•Professor Jonas Hedlund (main applicant)•Professor Oleg Antzutkin•Professor Pär Weihed•Professor Hanumantha Rao Kota •Professor Bo Björkman•Professor Björn Öhlander•Professor Rikard Gebart

The foundation granted 5.5 M SEK

Application to the Kempe Foundation

Application for a microprobe

Applicants•Professor Kris Berglund•Professor Jonas Hedlund•Professor Oleg Antzutkin•Professor Pär Weihed (main applicant)•Professor Hanumantha Rao Kota •Professor Bo Björkman•Professor Björn Öhlander

The foundation granted 5 M SEK

I. The Magellan 400: extreme high-resolution SEM

The following instruments were purchased and installed this summer

•FEI Magellan 400 XHR-SEM:

- Among all major HR-SEM instruments on the market, this SEM instrument produced by far the best high resolution images on our samples. - First microscope with subnanometric resolution:resolution of 0.8 nm at 1 kV in SE-mode.

•INCA Energy 450 system with X-MAX80 EDS detector (Oxford Instrument Ltd.)

- largest detector crystal on the marker: 80 mm2 area- combined image analysis and elemental analysis

•Total cost 7 M SEK

FEI Magellan 400 XHR-SEM

Beam 

decceleration

Monochromator

vCD

Sample

TLD

Beam 5 detectors: ETD, TLD, vCD, STEM and EDS

•ETD: Everhart-Thornley detector•TLD: through-lens detector (in-lens) •vCD: low voltage high contrast detector

Main features:

•Schottky emitter •Sub-nanometer resolution from 1 to 30kV •Beam decceleration•Monochromator•Beam current down to 0.8 pA

Best instrument for high resolution on non-conductive samples.

Monochromator

Monochromator off Monochromator on

Gold nanoparticles

Nanocraks in zeolite films• growth of zeolite thin films for CO2 or renewable fuel separation • most of the defects <10 nm could never be resolved with a gold coating of 10 nm

Films of iron oxide nanoparticles• for sintering/heat treatment studies• for adsorption studies on an attenuated total reflection (ATR)crystal with Fourrier Transform Infrared (FTIR) spectroscopy: e.g. arsenates or flotation reagents

Film of ferryhydrite nanoparticles Film of magnetite nanoparticles

Nanocellular structures of rare-earth oxides• synthesis of fluorescent nanoparticles by combustion synthesis

(a) Original nanocellular structure of yttrium oxide (b, c) Same structure after addition of 10% sulfate and calcination at 960°C or 4 hrs:

(b) obtained on a JEOL 6460lv; (c) obtained on the Magellan instrument.

STEM detector detector for scanning transmission electron microscopy:• BF: bright field• DF: dark field• HAADF (outer sgements): high angle annular dark field

STEM detector Imaging of thin specimen <50 nm:• resolution of 0.6 nm• example: zeolite seeds, complementary data obtained byTLD and STEM

EDS detector Energy dispersive spectroscopy: • large area detector = more data in a shorter time• ideal for fast mapping• ideal for working with low acceleration voltages small interaction volume = high spatial resolution (~50 nm)

II. The Merlin: SEM for nanoanalytics

The following instruments will be purchased soon and installed before next summer

• Carl Zeiss’ Merlin HR-SEM:

- special design, which gives rise to unique contrasts - combination of high resolution and high current:resolution of 0.9 nm at 15 kV, currents up to 300 nA .

•INCA Wave 450 system with WDS spectrometer and X- MAX20 EDS detector (Oxford Instrument Ltd.)

- elemental analysis capability equivalent to a microprobe, except in terms of throughput- mineral liberation analysis software

3 detectors: SE, EsB, AsB

• SE: for surface imaging• EsB: for material contrast• AsB: for crystallographic contrast

Main features:

•Special design of the column, which focuses electrons emitted from the sample on 2 different detectors depending on their energies•Grid to collect only low loss energy backscattered electrons•Electrostatic lens which enables selection of widely dispersed backscatterred electrons•Local charge compensation

Best instrument for nanoanalytics

Carl Zeiss’ Merlin HR-SEM

Conclusion

Conclusion•We have the best SEM for high resolution work available on the market, with the highest low kV resolution of all instruments in the world.

•These systems will most likely bring the research in numerous research areas at the University a great step forward.

•It is now up to the researchers to exploit the possibilities the new instrument offers.

•The future is bright!

Thank you for your attention !