Morphology Control of PbZrxTi1-xO3 Crystallites under Alkaline Hydrothermal Conditions

Outstanding ferroelectric and piezoelectric properties of PbZrxTi1-xO3 (PZT) make nano and sub-micrometer particles of this material interesting for future nanotechnological applications as well as for fundamental studies of ferroelectricity at the nanoscale. In the present work, the prospects of a new hydrothermal approach were explored to control the particle size, aggregation stage, and composition of the PZT with the target composition of Zr/Ti = 60/40 (x = 0.6). Starting with water-soluble Zr-, Ti-, and Pb-precursors, the PZT formation was examined in the broad base (KOH) concentration range. The PZT particle size and composition were governed by the ratio of KOH with respect to Pb and not by the absolute KOH concentration (c(KOH)). The incorporation of Zr into the PZT perovskite phase began to decline at KOH:Pb <= 1.7 and at KOH:Pb > 20. In the concentration range of 20 >= KOH:Pb > 1.5, the PZT particles adopted a cube-like shape, the size of which decreased with a decrease in the KOH:Pb ratio. The smallest (<200 nm) and well-separated PZT particles were obtained at KOH:Pb = 1.7. The prevailing PZT crystal structure at a Zr/Ti composition of around 60/40 was rhombohedral; the tetragonal phase also began to appear in Ti-richer PZT compositions (Zr/Ti <= 50/50). The developed understanding established the basis for further tailoring of PZT particle morphologies for application-oriented or fundamental research.

Automated summary

The hydrothermal approach was utilized to control the particle size, aggregation stage, and composition of PbZrxTi1-xO3 (PZT) particles. The results showed that the size and composition of PZT particles were determined by the ratio of KOH with respect to Pb, rather than the absolute KOH concentration. In a specific ratio range, the PZT particles adopted a cube-like shape, with the size decreasing as the ratio decreased. The crystal structure of PZT changed gradually from rhombohedral to tetragonal with an increase in the Zr/Ti ratio.