Thermally induced formation of metastable nanocomposites in amorphous Cr-Zr-O thin films deposited using reactive ion beam sputtering
Abstract
Successive crystallization of amorphous Cr-Zr-O thin films, formation of the (Cr,Zr)(2)O-3/(Zr, Cr)O-2 nanocomposites and the thermally induced changes in the hexagonal crystal structure of metastable (Cr, Zr)(2)O-3 were investigated by means of in situ high-temperature synchrotron diffraction experiments up to 1100 degrees C. The thin films were deposited at room temperature by using reactive ion beam sputtering, and contained 3-15 at.% Zr.
At low Zr concentrations, chromium-rich (Cr,Zr)(2)O-3 crystallized first, while the crystallization of zirconium-rich (Zr,Cr)O-2 was retarded. Increasing amount of zirconium shifted the onset of crystallization in both phases to higher temperatures.
For 3 at.% of zirconium in amorphous Cr-Zr-O, (Cr,Zr)(2)O-3 crystallized at 600 degrees C. At 8 at.% Zr in the films, the crystallization of (Cr,Zr)(2)O-3 started at 700 degrees C.
At 15 at.% Zr, the Cr-Zr-O films remained amorphous up to the annealing temperature of 1000 degrees C. Metastable hexagonal (Cr,Zr)(2)O-3 accommodated up to similar to 3 at.% Zr.
Excess of zirconium formed tetragonal zirconia, which was stabilized by chromium.