Fundamental Studies of Single Crystal Alpha Alumina Microstructures Produced by Irradiation with Zirconium Ions

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.