Transmission electron microscopy study of high-dose iron-implanted sapphire

The microstructure of α-Al2O3 implanted with iron at energy of 50 keV to a dose of 1 × 1017 ions/cm2 at room temperature has been studied. The iron concentration profile shows a well-defined peak at ~ 50 nm from the surface, in agreement with the calculated value. The implanted Fe ions precipitate as the α-Fe particles during annealing in a reducing atmosphere. The voids around α-Fe particles and some large iron particles both have faceted outlines. Through the analysis of the composite selected-area electron diffraction pattern (SAED) and Moiré fringes, the orientation relationship (OR) between α-Fe particles and sapphire was determined to be (111)α-Fe//(0001)sapphire and [11¯0]α-Fe//[112¯0]sapphire. Some deviation from this OR was detected in a few α-Fe particles, which is less than 3°. The coincidence of reciprocal lattice point (CRLP) method was utilized to confirm that this OR is preferred in the α-Fe/sapphire system.