Belay Zeleke Dilnesa - Eawag-Empa Library

CHAPTER 3 SYNTHETIC FE-CONTAINING HYDRATES
phases (no systematic peak shifts) while no intermediate phase formed (Fig. 17). The
intensity of the small intermediate peak at 11.39° 2θ was found to depend on the water
content as it decreased upon drying. To index the reflections and to determine the layer
thickness and the unit cell parameter a, a Le Bail fitting was performed. The results are
shown in Fig. 18 and Fig. 19, respectively. No significant variation of both parameters
with varying Al mole fraction was observed compared to end member values. These
results clearly confirm the absence of a solid solution between Al-Mc and Fe-Mc, in
contrast to the findings reported elsewhere [70]. Thus, comparison of the XRD pattern
further corroborate that 3CaOAl2O3CaCO311H2O and 3CaOFe2O3CaCO312H2O have
different structural symmetries, carbonate location and different amounts of water
molecules in the interlayer.
Intensity Intensity [arb. [arb. units]
Fe-Mc
*
Al-Mc
1.0
0.7
0.5
10 11 12 2CuK 2CuK
13 0.3
0.0
14
Al/(Al+Fe) ratio
Fig. 17 XRD pattern of the Al/Fe-Mc after 3 years hydration time at 20 °C * peak due to
additional water in Mc.
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