Structure and Properties of Hydrogenated Ca, Sr, Ba, and Eu Silicides
among CrBꢀtype and other (Zintl) compounds for successful
hydrogenation reactions.
Acknowledgement
We thank Dr. Gudrun Auffermann at the MaxꢀPlanck Institute for
Chemical Physics of Solids (Dresden, Germany) for the determination
of the hydrogen content. Electron microscopy was done on the microꢀ
scope of the EMEZ (electron microscopy ETH Zürich).
Experimental Section
Synthesis
CaSi, SrSi, BaSi, and EuSi were prepared by reacting the redistilled
metals in stoichiometric amounts (Ca: Alfa Aesar, 99.9 %; Sr: Fluka,
99 %; Ba: Aldrich, 99 %; Eu: ABCR, 99 %) with silicon (Fluka,
99.999 %) in closed tantalum ampoules running the following temperꢀ
ature program: heating up from 298 to 1400 K in 10 h; heating at
1500 K for 1 h and at 1350 K for 10 h; quenching the products finally
in cold water. Hereby, the wellꢀcrystallized silicides were obtained in
pure form according to XRD investigations. The samples were placed
into an autoclave (about 200 mg). The reactor was heated up to 450 K
jacket temperature and a hydrogen pressure (H2: PanGas, 99.999
99 %) of about 90 bar was applied for one day. To avoid any reaction
of starting materials and products with air, the samples were always
handled in a gloveꢀbox under argon atmosphere. In particular, the reacꢀ
tor for hydrogenation was filled, closed and opened under the same
inert conditions.
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