Structural investigations of potential relaxor ferroelectrical materials with complex metal oxide compositions

The focus of this project has been the complementary application of neutron powder diffraction, synchrotron X ray powder diffraction and electron diffraction in the structural analysis of potential relaxer ferroelectric materials. Two structure types have been investigated in this work, complex defect perovskite structures (Sr0.8Ti0.6-x,Zrx03) and mixed occupancy tungsten bronze type structures (Bax,Sr3-xTi1-yZryNb4015). Neutron powder diffraction experiments undertaken on ECHIDNA at ANSTO have revealed the presence of superlattice reflections in the x = 0.24 member of the Sr0.8Ti0.6-xZrxO3 series. These reflections indicate a symmetry lowering phase transition and were not visible in the synchrotron X ray diffraction pattern. The four end members of the BaxSrx-3Ti1-yZryNb4015 series have been previously investigated. However, discrepancies remain in the literature over the symmetry and cell of Sr3TiNb4015 [1-3]. In addition Sr3ZrNb4015 has only been listed once in a large table of compounds and no detailed structural characterization has been reported. This presentation reveals a new unit cell and symmetry for Sr3ZrNb4015, as well as the first detailed structural analysis of Sr3ZrNb4015. Interesting thermal behaviour across the BaxSr3-xTiNb4015 composition range as well as a morphotropic phase boundary will be reported, in addition to a composition dependent phase transition in the BaxSr3-xZrNb4015 series.