Micro-Raman and micro-infrared spectroscopic studies of Pb- and Au-irradiatedZrSiO4: Optical properties, structural damage, and amorphization

Abstract

The optical properties of damaged periodic and aperiodic domains created by ${\mathrm{Pb}}^{+}$ $(280\phantom{\rule{0.3em}{0ex}}\mathrm{keV})$ and ${\mathrm{Au}}^{4+}$ $(10\phantom{\rule{0.3em}{0ex}}\mathrm{MeV})$ implantation of zircon were studied using micro-infrared (IR) and micro-Raman spectroscopy. The ${\mathrm{Pb}}^{+}$ and ${\mathrm{Au}}^{4+}$ irradiations caused a dramatic decrease in the IR reflectivity similar to that observed for metamict natural zircon. The irradiation with $10\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ ${\mathrm{Au}}^{4+}$ ions (to fluences of $1\ifmmode\times\else\texttimes\fi{}{10}^{15}\phantom{\rule{0.3em}{0ex}}{\mathrm{Au}}^{4+}\phantom{\rule{0.3em}{0ex}}\mathrm{ions}∕{\mathrm{cm}}^{2}$) also results in the formation of an amorphized phase similar to that observed in metamict zircon. These results show that high-energy, heavy-ion irradiations provide a good simulation of the ballistic effects of the recoil nucleus of an alpha-decay event and, in both cases, the result is the creation of aperiodic domains. Additional IR and Raman features were recorded in samples irradiated with $280\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ ${\mathrm{Pb}}^{+}$ ions (to fluences of $1\ifmmode\times\else\texttimes\fi{}{10}^{14}$ and $1\ifmmode\times\else\texttimes\fi{}{10}^{15}\phantom{\rule{0.3em}{0ex}}{\mathrm{Pb}}^{+}\phantom{\rule{0.3em}{0ex}}\mathrm{ions}∕{\mathrm{cm}}^{2}$), indicating the formation of an irradiation-induced additional phase(s). The frequencies of the features are consistent with lead silicates, $\mathrm{Zr}{\mathrm{O}}_{2}$, and $\mathrm{Si}{\mathrm{O}}_{2}$. The results show that spectral features of the ${\mathrm{Au}}^{4+}$- and ${\mathrm{Pb}}^{+}$-irradiated zircon are different from those of quenched $\mathrm{Zr}\mathrm{Si}{\mathrm{O}}_{4}$ melts, and the finding further confirms that the amorphous state produced by high-energy ion irradiations is structurally different from the glassy state that results from quenching a high temperature melt. In contrast to significant changes in the frequency and width of the Raman ${\ensuremath{\nu}}_{3}$ band observed in metamict zircon, the ${\mathrm{Pb}}^{+}$ and ${\mathrm{Au}}^{4+}$ irradiations do not cause similar variations, indicating that the remaining zircon crystalline domains in irradiated samples have a crystalline structure with fewer defects than those of metamict zircon.