Nuclear quadrupole interaction at 181Ta in hafnium dioxide fiber: Time differential perturbed angular correlation measurements and ab initio calculations

The thermal behavior of hafnium dioxide fiber has been investigated with the aid of time differential perturbed angular correlation (TDPAC) technique along with XRD and SEM measurements. This study has proved a good thermal stability of the fibrous material up to 1173 K and the fiber loses its crystallinity to a meager extent at 1673 K. No phase transition has been observed up to 1673 K in this fiber. TDPAC parameters for the HfO2 fiber annealed at 1173 K are ωQ=124.6 (3) Mrad/s and η=0.36 (1). These values remain unaltered for the HfO2 fiber annealed even at 1673 K. Electronic structure calculations based on the density functional theory (DFT) for HfO2 doped with tantalum impurity have been performed and the calculated EFG parameters are in reasonable agreement with the experimental values.

► HfO2 fiber, an RIB target material studied by TDPAC, SEM and XRD, proved thermally stable up to 1673 K. ► XRD and TDPAC parameters indicate a partial loss of crystallinity in HfO2 fiber. ► No phase transition has been observed up to 1673 K in this fiber. ► EFG parameters calculated based on DFT are in reasonable agreement with the experimental value. ► Calculated density of states indicates that Ta doping does not affect the neighboring Hf atoms.