CHARACTERIZATION OF POLYCRYSTALLINE ALPHA-AL2O3, ZIRCONIUM IMPLANTED AND ANNEALED AT VARIOUS TEMPERATURES

Polycrystalline α-Al2O3 samples implanted with 50-190 keV Zr ions from 5 × 1016 to 2.5 × 1017 ions/cm2 have been investigated. A physico-chemical characterization of the as-implanted specimen has been carried out. By using XPS. it is shown that the four chemical states ZrO2, Al2O3, Al and Zr are present in the implanted layer. Moreover, TEM indicates no precipitate formation. Thermal annealings have been performed between 700 and 1600°C for one hour in an oxidizing atmosphere. RBS and SEM techniques, used to follow the evolution of the zirconium versus the annealing temperature, show that under air, from 700°C, zirconium is entirely oxidized. Up to 1000°C small oxide precipitates are formed. The ZrO2 grain size increases with temperature between 1200 and 1600°C. At 1600°C a heterogeneous distribution of ZrO2 nodules (∼ 0.7 ω) is observed in conjunction with Zr release from the surface (~ 60% of Zr loss). Moreover, this study is completed by in situ annealing TEM observations. © 1990.