electron microscopy



Recent Research Highlights


Details of the Real Structure
of CdxNb6(O,F)16

The structure of CdxNb6(O,F)16 crystallizes in the orthorhombic LiNb6O15F structure type (space group Pmma). Light microscopy and scanning electron microscopy imaging reveals a frequent intergrowth of crystallites on the micrometer scale while HAADF-STEM images show perfect order in most areas. However, a single grain boundary was found with the structures in the adjacent domains tilted by 4° in respect of each other (see image). The adjacent domains are coherently connected in parts of the interface but frequently defects occur at irregular intervals.

A Detailed Structural Analysis of CdxNb6(O,F)16
F. Krumeich and M. Wörle
Z. anorg. allgem. Chem. 2019, 645, 753–757


HAADF-STEM image showing the defective area (red) between the well-ordered domain (blue and green). The structures in both domains are tilted by ca. 4° in respect of each other.


Catalyst Deactivation in Fluid Catalytic Cracking

Fluid catalytic cracking (FCC), an important process in chemical industry, converts the heavy fractions of crude oil into valuable petrol and chemicals. The catalyst is a spherical composite of zeolite and clay that decreases in catalytic activity during long-term operation. By using a range of electron microscopy and elemental mapping techniques, the structural and chemical characteristics of pristine and progressively deactivated catalyst particles have been characterized from the micro- down to the nanometer scale. An increasingly dense amorphous silica alumina layer wrapping the particles is formed during operation. Fe and Ca are the main impurities in this envelope.

A three-dimensional view of structural changes caused by deactivation of fluid catalytic cracking catalysts
J. Ihli, R. R. Jacob, M. Holler, M. Guizar Sicairos, A. Diaz, J. C. da Silva, D. Ferreira Sanchez, F. Krumeich, D. Grolimund, M. Taddei, W.-C. Cheng, Y. Y. Shu, A. Menzel, and J. A. van Bokhoven
Nature Commun.
2017, 8, 809, DOI

Localization and Speciation of Iron Impurities within a Fluid Catalytic Cracking Catalyst
J. Ihli, D. Ferreira Sanchez, J. Rosh, V. Cuartero, O. Mathon, F. Krumeich, C. Borca, T. Huthwelker, W.-C. Cheng, Y.-Y. Shu, S. Pascarelli, D. Grolimund, A. Menzel, and J. A. van Bokhoven
Angew. Chem. Int. Ed. 2017, 56, 14031-14035, DOI

Structural changes in deactivated fluid catalytic cracking catalysts determined by electron microscopy
F. Krumeich, J. Ihli, Y.Y. Shu, W.-C. Cheng, and J. A. van Bokhoven

ACS Catal.
2018, 8, 4591–459, DOI



Scheme demonstrating the EM methods used to explore the structure and chemistry of FCC particles and their cross-sections at different length scales.


Luminescent Lead Halide Perovskite Nanocrystals Embedded in Mesoporous Silica

By soaking mesoporous silica with perovskite precursor solutions followed by drying, lead halide perovskite nanocrystals are formed inside the silica pores (Figure: HAADF-STEM image of a SiO2 sample with 7 nm pores partially filled with CsPbI3 nanoparticles). This material shows very bright photoluminescence (inset).

Harnessing Defect-Tolerance at the Nanoscale: Highly Luminescent Lead Halide Perovskite Nanocrystals in Mesoporous Silica Matrices
D. N. Dirin, L. Protesescu, D. Trummer, I. V. Kochetygov, S. Yakunin, F. Krumeich, N. P. Stadie, and M. V. Kovalenko
Nano Letters
16 (2016) 5866−5874, DOI


In-Situ Heating of Carbon-Coated LiFePO4

The thermal behavior of core-shell carbon-coated LiFePO4 nanoparticles, a promising battery material made by flame spray pyrolysis, during annealing was investigated by in-situ TEM. At a temperature of T = 700 °C, LiFePO4 starts to diffuse through the carbon shell resulting in cavities inside the mostly intact carbon shell. By increasing the temperature to T = 800 °C, the initial core-shell morphology is converted into open carbon shells and bulky LiFePO4 particles.

Thermal Annealing Dynamics of Carbon-Coated LiFePO4 Nanoparticles Studied by In-Situ Analysis
F. Krumeich, O. Waser, and S. E. Pratsinis
J. Solid State Chem.
242 (2016) 96–102, DOI



Functionalized BN / Hollow Zeolites

Single Atoms in Catalysts /
Imaging Li in LiBC

Phase Contrast in STEM / Tin Nanocrystals for Battery Applications

Dodecagonal Quasicrystals / Behaviour of Nanoparticles in a Waste Incineration Plant

Catalyst Characterization / Coated Nanoparticles /
Optimization of Catalysts

Cation Ordering in Perovskites / Leaching of ZSM-5 Zeolithes
Cytoxicity of Nanoparticles /
Structure Determination of Bi6S2O15



Publication lists:

ORCID iD iconorcid.org/0000-0001-5625-1536 ----- Scopus author

ETH Zürich | ETH chemistry department | ETH inorganic chemistry

modified: 24 June, 2019 by F. Krumeich | © ETH Zürich and the authors