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Periodic Cation Segregation in Cs0.44[Nb2.54W2.46O14] Quantified by High-Resolution Scanning Transmission Electron Microscopy

Published online by Cambridge University Press:  01 July 2014

Markus Heidelmann ,
Juri Barthel ,
Gerhard Cox  and
Thomas E. Weirich
Markus Heidelmann*
Affiliation:
Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
Juri Barthel
Affiliation:
Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
Gerhard Cox
Affiliation:
BASF SE, Department of Polymer Physics, 67065 Ludwigshafen, Germany
Thomas E. Weirich
Affiliation:
Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen, Germany Institute of Crystallography, RWTH Aachen University, 52056 Aachen, Germany
*
*Corresponding author. [email protected]
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Abstract

The atomic structure of Cs0.44[Nb2.54W2.46O14] closely resembles the structure of the most active catalyst for the synthesis of acrylic acid, the M1 phase of ${\rm Mo}_{{{\rm 10}}} {\rm V}_{{\rm 2}}^{{{\rm 4{\plus}}}} {\rm Nb}_{2} {\rm TeO}_{{{\rm 42}{\minus}x}} $ . Consistently with observations made for the latter compound, the high-angle electron scattering signal recorded by scanning transmission electron microscopy shows a significant intensity variation, which repeats periodically with the projected crystallographic unit cell. The occupation factors for the individual mixed Nb/W atomic columns are extracted from the observed intensity variations. For this purpose, experimental images and simulated images are compared on an identical intensity scale, which enables a quantification of the cation distribution. According to our analysis specific sites possess low tungsten concentrations of 25%, whereas other sites have tungsten concentrations above 70%. These findings allow us to refine the existing structure model of the target compound, which has until now described a uniform distribution of the niobium and tungsten atoms in the unit cell, showing that the similarity between Cs0.44[Nb2.54W2.46O14] and the related catalytic compounds also extends to the level of the cation segregation.

Keywords

HRSTEMmultislice calculationatomic column compositioncation segregation
Type
Materials Applications
Information
Microscopy and Microanalysis , Volume 20 , Issue 5 , October 2014 , pp. 1453 - 1462
Copyright
© Microscopy Society of America 2014 

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Footnotes

✠

Dedicated to the memory of Dr. Gerhard Cox, who passed away on February 17, 2014.

References

Bar-Sadan, M., Barthel, J., Shtrikman, H. & Houben, L. (2012). Direct imaging of single Au atoms within GaAs nanowires. Nano Lett 12, 2352–2356.CrossRefGoogle ScholarPubMed
Barthel, J. (2013). Dr. Probe – high-resolution (S)TEM image simulation software, July. Available at http://www.er-c.org/barthel/drprobe/Google Scholar
Barthel, J., Weirich, T.E., Cox, G., Hibst, H. & Thust, A. (2010). Structure of Cs0.5[Nb2.5W2.5O14] analysed by focal-series reconstruction and crystallographic image processing. Acta Materialia 58, 3764–3772.CrossRefGoogle Scholar
Blom, D.A., Pyrz, W.D., Vogt, T. & Buttrey, D.J. (2009). Aberration-corrected STEM investigation of the M2 phase of MoVNbTeO selective oxidation catalyst. J Electron Microsc 58, 193–198.CrossRefGoogle ScholarPubMed
Carlino, E. & Grillo, V. (2005). Atomic-resolution quantitative composition analysis using scanning transmission electron microscopy Z-contrast experiments. Phys Rev B 71, 235–303.CrossRefGoogle Scholar
Cowley, J.M. & Moodie, A.F. (1957). The scattering of electrons by atoms and crystals. I. A new theoretical approach. Acta Crystallogr 10, 609–619.CrossRefGoogle Scholar
Dey, K.R., Gesing, T.M., Rüscher, C.H. & Hussain, A. (2002). Crystal structure of caesium niobium tungsten bronzes Cs0.23(Nb0.09W0.91)O3 and Cs0.29(Nb0.10W0.90)O3. Zeitschrift für Kristallographie 217, 461–462.Google Scholar
Dwyer, C., Erni, R. & Etheridge, J. (2010). Measurement of effective source distribution and its importance for quantitative interpretation of STEM images. Ultramicroscopy 110, 952–957.CrossRefGoogle Scholar
Grillo, V., Carlino, E. & Glas, F. (2008). Influence of the static atomic displacement on atomic resolution Z-contrast imaging. Phys Rev B 77, 054103.CrossRefGoogle Scholar
Haider, M., Uhlemann, S., Schwan, E., Rose, H., Kabius, B. & Urban, K. (1998). Electron microscopy image enhanced. Nature 392, 768–769.CrossRefGoogle Scholar
Hibst, H., Rosowski, F. & Cox, G. (2006). New Cs-containing Mo-V4+ based oxides with the structure of the M1 phase – base for new catalysts for the direct alkane activation. Catal Today 117, 234–241.CrossRefGoogle Scholar
Kirkland, A.I. & Saxton, W.O. (2002). Cation segregation in Nb16W18O94 using high angle annular dark field scanning transmission electron microscopy and image processing. J Microsc 206, 1–6.CrossRefGoogle ScholarPubMed
Krumeich, F., Wörle, M. & Hussain, A. (2000). Superstructure and twinning in the tetragonal tungsten bronze-type phase Nb7W10O47. J Solid State Chem 149, 428–433.CrossRefGoogle Scholar
LeBeau, J.M. & Stemmer, S. (2008). Experimental quantification of annular dark-field images in scanning transmission electron microscopy. Ultramicroscopy 108, 1653–1658.CrossRefGoogle ScholarPubMed
LeBeau, J.M., Findlay, S.D., Allen, L.J. & Stemmer, S. (2008). Quantitative atomic resolution scanning transmission electron microscopy. Phys Rev Lett 100, 206101.CrossRefGoogle ScholarPubMed
LeBeau, J.M., Findlay, S.D., Allen, L.J. & Stemmer, S. (2010). Standardless atom counting in scanning transmission electron microscopy. Nano Lett 10, 4405–4408.CrossRefGoogle ScholarPubMed
Li, X., Buttrey, D.J., Blom, D.A. & Vogt, T. (2011). Improvement of the Structural Model for the M1 Phase Mo–V–Nb–Te–O Propane (Amm) oxidation Catalyst. Top Catal 54, 614–626.CrossRefGoogle Scholar
Loane, R.F., Xu, P. & Silcox, J. (1991). Thermal vibrations in convergent-beam electron diffraction. Acta Crystallogr Sect A 47, 267–278.CrossRefGoogle Scholar
Lundberg, M. & Sundberg, M. (1993). New complex structures in the cesium-niobium-tungsten-oxide system revealed by HREM. Ultramicroscopy 52, 429–435.CrossRefGoogle Scholar
Momma, K. & Izumi, F. (2011). VESTA3 for three-dimensional visualization of crystal, volumetric and morphology data. J Appl Crystallogr 44, 1272–1276.CrossRefGoogle Scholar
Müller, H., Uhlemann, S., Hartel, P. & Haider, M. (2006). Advancing the hexapole Cs-corrector for the scanning transmission electron microscope. Microsc Microanal 12, 442–455.CrossRefGoogle ScholarPubMed
Pennycook, S.J. (1989). Z-contrast stem for materials science. Ultramicroscopy 30, 58–69.CrossRefGoogle Scholar
Pennycook, S.J. & Jesson, D.E. (1990). High-resolution incoherent imaging of crystals. Phys Rev Lett 64, 938–941.CrossRefGoogle ScholarPubMed
Perovic, D.D., Rossouw, C.J. & Howie, A. (1993). Imaging elastic strains in high-angle annular dark field scanning transmission electron microscopy. Ultramicroscopy 52, 353–359.CrossRefGoogle Scholar
Pyrz, W.D., Blom, D.A., Vogt, T. & Buttrey, D.J. (2008 a). Direct imaging of the MoVTeNbO M1 phase using an aberration-corrected high-resolution scanning transmission electron microscope. Angew Chem Int Edit 47, 2788–2791.CrossRefGoogle ScholarPubMed
Pyrz, W.D., Blom, D.A., Shiju, N.R., Guliants, V.V., Vogt, T. & Buttrey, D.J. (2008 b). Using aberration-corrected STEM imaging to explore chemical and structural variations in the M1 phase of the MoVNbTeO oxidation catalyst. J Phys Chem C 112, 10043–10049.CrossRefGoogle Scholar
Rosenauer, A., Gries, K., Müller, K., Pretorius, A., Schowalter, M., Avramescu, A., Engl, K. & Lutgen, S. (2009). Measurement of specimen thickness and composition in using high-angle annular dark field images. Ultramicroscopy 109, 1171–1182.CrossRefGoogle ScholarPubMed
Rosenauer, A., Mehrtens, T., Müller, K., Gries, K., Schowalter, M., Satyam, P.V., Bley, S., Tessarek, C., Hommel, D., Sebald, K., Seyfried, M., Gutowski, J., Avramescu, A., Engl, K. & Lutgen, S. (2011). Composition mapping in InGaN by scanning transmission electron microscopy. Ultramicroscopy 111, 1316–1327.CrossRefGoogle ScholarPubMed
Trasobares, S., López-Haro, M., Kociak, M., March, K., deLaPea, F., Perez-Omil, J.A., Calvino, J.J., Lugg, N.R., D’Alfonso, L.J., Allen, A.J. & Colliex, C. (2011). Chemical imaging at atomic resolution as a technique to refine the local structure of nanocrystals. Angewandte Chemie 123, 898–902.CrossRefGoogle Scholar
Voyles, P.M., Muller, D.A., Grazul, J.L., Citrin, P.H. & Gossmann, H.-J.L. (2002). Atomic-scale imaging of individual dopant atoms and clusters in highly n-type bulk Si. Nature 416, 826–829.CrossRefGoogle ScholarPubMed
Weickenmeier, A. & Kohl, H. (1991). Computation of absorptive form factors for high-energy electron diffraction. Acta Crystallogr Sect A 47, 590–597.CrossRefGoogle Scholar
Weirich, T.E., Portillo, J., Cox, G., Hibst, H. & Nicolopoulos, S. (2006). Ab initio determination of the framework structure of the heavy-metal oxide Csx[Nb2.54W2.46O14] from 100 kV precession electron diffraction data. Ultramicroscopy 106, 164–175.CrossRefGoogle Scholar
Xu, P., Loane, R.F. & Silcox, J. (1991). Energy-filtered convergent-beam electron diffraction in STEM. Ultramicroscopy 38, 127–133.CrossRefGoogle Scholar
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