The Formation of Cr-Al Spinel under a Reductive Atmosphere
Oleksandr Shtyka, Waldemar Maniukiewicz, Radosław Ciesielski, Adam Kêdziora, Viktar Shatsila, Tomasz Sierański, Tomasz Maniecki
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.