Date of Award
Doctor of Philosophy
Materials Science and Engineering
Carl J. McHargue
Kurt E. Sickafus, William J. Weber, Ali Passian, Claudia Rawn
This research has discovered the following new information:
a) The threshold fluence for amorphization of single crystal α-Al2O3 [alpha alumina] samples irradiated with 175 keV Zr+ [Zr+] ions at room temperature is 1.5×1016 [1.5E16] Zr/cm2 [Zr+/cm2] which is a much lower fluence than the previously thought.
b) A buried amorphous layer sandwiched between two highly-damaged crystalline regions was observed in samples irradiated with 175 keV Zr+ to a fluence of 1.5×1016 Zr+/cm2 and higher at room temperature.The amorphous region contains short range order similar to γ-Al2O3 [gamma alumina]; it is deficient in oxygen containing Zr-rich nano-clusters.
c) Ion-beam induced epitaxial recrystallization occurred at room temperature due to oxygen irradiation of the amorphous phase. It is the first observation at low temperature.
d) Irradiation of Zr-implanted α-Al2O3 [alpha alumina] samples with oxygen decreased the F-type centers concentrations.
e) Post irradiation thermal annealing of Zr-implanted α-Al2O3 samples induced amorphous to γ-Al2O3 transformation at the interface between amorphous and damaged regions.
Sina, Younes, "Fundamental Studies of Single Crystal Alpha Alumina Microstructures Produced by Irradiation with Zirconium Ions. " PhD diss., University of Tennessee, 2013.