Complex structure and Mössbauer effect observed in the course of phase transitions in PbZr 0.72 Sn 0.28 O 3 single crystal

The Mössbauer effect was used to study the structural transitions in a PbZr Sn O single crystal. Two kinds of quadrupole splittings were registered and connected with two different environments of the Sn ion occupying the center of SnO octahedra. What is responsible for the existence of these two environments is the disorder in tilts of oxygen octahedra and antiparallel shifts of pairs of lead ions. Both disorders decide on structural transitions which the PbZr Sn O single crystal undergoes. The two kinds of quadruple splittings that have been observed do not disappear at temperatures far above phase transitions. This indicates that the structure of the paraelectric phase is locally non-centrosymmetric and confirms pre-transitional effects previously reported for Sn doped PbZrO single crystals.