TY  - JOUR
AU  - Heidelmann, Markus
AU  - Barthel, Juri
AU  - Cox, Gerhard
AU  - Weirich, Thomas
TI  - Periodic Cation Segregation in Cs$_{0.44}$[Nb$_{2.54}$W$_{2.46}$O$_{14}$] Quantified by High-Resolution Scanning Transmission Electron Microscopy
JO  - Microscopy and microanalysis
VL  - 20
IS  - 5
SN  - 1431-9276
CY  - New York, NY
PB  - Cambridge University Press
M1  - FZJ-2014-03896
SP  - 1453-1462
PY  - 2014
AB  - 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 . 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000345742900014
DO  - DOI:10.1017/S1431927614001330
UR  - https://juser.fz-juelich.de/record/154603
ER  -