Field of Expertise: Advanced Material Science

Modification of PZT with Bismuth: a Structural and Electrical Study
Theresa Kainz, Franz Mautner, Klaus Reichmann
Christian Doppler Laboratory for Advanced Ferroic Oxides
14:40 - 15:00 Thursday 23 October 2014 Rechbauerstrasse 12, HSII

In this contribution the influence of Bismuth as substitution of Lead in the solid solution Lead-Zirconate Lead-Titanate (PZT), on the Zirconium-rich, antiferroelectric side, was investigated. In literature the modification of PZT with Lanthanum is widely investigated. The introduction of the aliovalent La3+ on the Pb-site induces important changes in electrical and structural properties and additionally creates vacancies on the Pb-site due to the maintenance of electrical neutrality. It disrupts the long-range ordering and therefore suppresses the stability of the ferroelectric state. As comparison the donor dopant Bismuth was added and the changes in electrical and structural properties were studied. With respect to the radius in twelve-fold coordination, the electronic structure (stereochemically active lone pair) and the resulting high polarisability the Bismuth ion Bi3+ resembles the Lead ion Pb2+.

A wide range of compositions of the formula Pb1-1,5xBixVPb”0,5xZr0,95Ti0,05O3 (x= 0,005-0,12) were prepared by the conventional solid state synthesis method. The increase in Bismuth addition reduces the distortion of the oxygen octahedra of the unit cell and provides a significant number of lattice vacancies at the A-site. It creates more structural disorder in the PZT system and hence a more diffuse phase transition.

Sintered samples were structurally investigated by X-ray spectroscopy. The change in the cell volume and the increase in tetragonality can be successively followed by further addition of Bismuth.

The dielectric constant and the loss factor were measured at several frequencies as a function of temperature revealing slight anomalies in the curves associated to phase transitions. Furthermore the remnant polarization could be determined from the hysteresis loop measurements.

All gained data were compared with the known influence of the Lanthanum modification in PZT.