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-c ubic phase transition at 700 K. The hyperfine interaction measured at Ta-18 1 probe corresponds to a static, asymmetric and disordered EFG. The hyperfi ne parameters V-zz and eta also display evident changes close to 673 K conf irming the phase transition observed by XRD. The line width of the quadrupo le interaction is relatively small compared with other perovskite-type comp ounds. (C) 2001 Published by Elsevier Science Ltd.