posted on 2024-10-31, 09:13authored byGina Peschel, Alexander Fuhrich, Dietrich Menzel, Mirali Jahangirzadeh Varjovi, Sergio Tosoni, Hans-Joachim Freund
The growth and structure
of two-dimensional iron silicate and iron
germanate films on Ru(0001) are studied. We investigate in detail
the temperature-dependent film formation of ultrathin layers of iron
silicate and iron germanate. These two-dimensional films can be seen
as model systems for more complex catalytically active structures,
such as zeolites, which can be used as selective catalysts or molecular
sieves. The experimental methods of XPS, LEED, LEEM, LEEM-IV, and
XPEEM are applied for correlated chemical and physical characterization
in situ and in real time, and DFT is applied for theoretical consideration.
We show that both systems can be considered as two-layered systems,
with a monolayer of iron oxide at the Ru interface and a monolayer
of silica or germania on top, respectively. The Fe-Fe distance in
the iron oxide layer is influenced by the Si-O-Si or Ge-O-Ge bond
length, in agreement with those of unstrained silicates or germanates.
Moreover, iron silicate can be prepared using different preparation
methods. The actual loading of Fe atoms is three per unit cell for
FeGeOx and only two for FeSiOx.