The Formation of Cr-Al Spinel under a Reductive Atmosphere
Oleksandr Shtyka1, Waldemar Maniukiewicz1, Radoslaw Ciesielski1
1Institute of General and Ecological Chemistry, Lodz University of Technology, 90924 Lodz, Poland.
Abstract:
In the present work, for the first time, the possibility of formation of CrAl2O4 was shown from the equimolar mixture of co-precipitated Al2O3 and Cr2O3 oxides under a reductive environment. The crystallographic properties of the formed compound were calculated using the DICVOL procedure. It was determined that it has a cubic crystal structure with space group Fd-3m and a unit cell parameter equal to 8.22(3) Å. The formed CrAl2O4 is not stable under ambient conditions and easily undergoes oxidation to α-Al2O3 and α-Cr2O3. The overall sequence of the phase transformations of co-precipitated oxides leading to the formation of spinel structure is proposed.
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