Local properties and phase transitions in Sn doped antiferroelectric PbHfO3 single crystal


Pb(Hf0.77Sn0.23)03 crystals were characterized using x-ray diffraction and 119Sn Mossbauer spectroscopy in a wide temperature range. The nature of two intermediate phases, situated between antiferroelectric ground-state and high temperature paraelectric phase, has been unveiled. The lower-temperature one is characterized by incommensurate modulations while the higher-T intermediate phase is defined by anti-phase rotations of oxygen octahedra. Two kinds of quadrupole splitting indicate that the environment of Sn is locally non-centrosymmetric even in the cubic phase.

X-ray diffraction signal of Pb(Hf0.77Sn0.23)03 crystal
Diffraction signatures of four phases observed for Pb(Hf0.77Sn0.23)03.
Diffuse streaks emerging from Bragg reflections at high temperatures are a signature of disorder (locally correlated displacements of Pb ions). They transform into broad maxima at 463 K, incommensurate peaks at 440 K and finally commensurate Bragg reflections at 385 K in the ground-state phase of this material.

Contact person: Marek Paściak
Collaborating institutions: Pedagogical Univerisity in Cracow, Military University in Warsaw, Silesian University in Katowice.