Microstructural evolution and nanocrystal formation in Pb+-implanted ZrSiO4 single crystals

Single crystals of ZrSiO4 (zircon) with a (110) orientation were implanted with 300 keV Pb+ at room temperature to fluences ranging from 10(14) to 10(17) ions/cm(2). The damage accumulation and microstructural evolution were analyzed by cross-sectional transmission electron microscopy (TEM) and glancing-angle x-ray diffraction (XRD). The experimental damage profiles as observed by TEM and XRD methods were compared to Monte Carlo simulations using the SRIM-2000 code. At the lowest ion fluence (10(14) ions/cm(2)), a buried amorphous layer formed in the zircon matrix. The surface layer is highly damaged and consists of zircon nanocrystals. The critical amorphization dose for zircon implanted with 300 keV Pb+ was in the range of 0.25-0.43 displacements per atom. With increasing ion fluence, the thickness of the amorphous layer increased. When the Pb concentration in the substrate exceeded similar to3.5 at. % (i.e., at 10(17) ions/cm(2)), Pb nanoparticles precipitated at room temperature and formed a layer similar to90 nm thick embedded within the amorphous zircon matrix. Effects of the displacement energies employed in the SRIM-2000 simulation on the damage profiles and the critical amorphization dose were also analyzed. (C) 2003 American Institute of Physics.