Abstract
The electric hyperfine interactions of implanted ${}^{111}{\mathrm{I}\mathrm{n}/}^{111}$Cd probes in ${\mathrm{HfO}}_{2}$ and ${\mathrm{ZrO}}_{2}$ powder samples have been measured by means of perturbed angular correlation (PAC) spectroscopy, in the temperature range between 15 K and 1273 K and at various oxygen pressures. In both oxides, several electric-field gradients (EFG) have been established that show pronounced similarities among the two oxides. The EFG having the largest fraction at room temperature has been assigned to the substitutional, defect-free cation site. Its quadrupole frequency ${\ensuremath{\nu}}_{Q}$=112 MHz and asymmetry parameter $\ensuremath{\eta}$=0.6, at 300 K, are almost identical in both oxides. The scaling of this EFG relative to that found with ${}^{181}{\mathrm{H}\mathrm{f}/}^{181}$Ta probes in ${\mathrm{HfO}}_{2}$ confirms the substitutional site. EFG calculations with the point charge and the cluster model for this site are compared with each other and with the data. The other EFG's observed have been attributed to different charge states of oxygen neighbor ions. Below 120 K, the spectra are strongly damped and indicate dynamic quadrupole interactions.
Published Version
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