Structural, electronic and hyperfine characterization of pure and Ta-dopedZrSiO4

Abstract

The electronic structure of pure and Ta-doped $\mathrm{ZrSi}{\mathrm{O}}_{4}$ in the tetragonal $I{4}_{1}/amd$ phase with and without defects has been studied using the ab initio full-potential linear augmented plane wave plus local orbitals method. From the determined charge densities, the electric field gradient tensor at native Zr sites and at Ta impurities localized on cation sites of $\mathrm{ZrSi}{\mathrm{O}}_{4}$ were derived and compared to experimental data obtained using hyperfine techniques. The effects of the Ta probe atom, including its different charge states on the lattice, are investigated. In addition, different types of defects, such as O or Si vacancies, Ta replacing Si, and Ta enclosed in microstructures of $\mathrm{Si}{\mathrm{O}}_{2}$ phases, are examined. The combination of experiments and theory enables us to identify the different interactions observed in Ta-doped $\mathrm{ZrSi}{\mathrm{O}}_{4}$ and to elucidate the role played by different defects.