Second order tetragonal-to-cubic phase transition in Sr0.5Ba0.5HfO3

We report the crystal structure together with the electric field gradient (EFG) tensor at the Hf site in Sr0.5Ba0.5HfO3 as a function of temperature. High-temperature X-ray diffraction data show a second-order tetragonal-to-cubic phase transition at 700 K. The hyperfine interaction measured at 181Ta probe corresponds to a static, asymmetric and disordered EFG. The hyperfine parameters Vzz and η also display evident changes close to 673 K confirming the phase transition observed by XRD. The line width of the quadrupole interaction is relatively small compared with other perovskite-type compounds.