Low temperature hydrothermal routes to various PZT stoichiometries

Abstract

The production of lead zirconate titanate (PZT) with a variation in Zr and Ti ratios using a hydrothermal method has been attempted. We show that when reactions are conducted at 160°C, for 4 h, the phase of PZT produced is independent of the initial Zr/Ti precursor ratio. In all cases we produce PZT with a crystal structure close to the morphotropic phase boundary, i.e. Zr/Ti≈52:48. The excess precursors either fail to react, or form amorphous and crystalline impurity phases that are detectable via powder XRD after the hydrothermal treatment. Using an excess of Pb precursor is shown to aid the crystallisation of the resultant PZT powder, as verified by SEM and FIB analysis.

Hydrothermal deposition of heteroepitaxial lead zirconate titanate nanostructures and thin films

“…8, was similar to that witnessed during the hydrothermal synthesis of freestanding PZT cubes without a Pbexcess. 17 Furthermore, in contrast to the Pb-excess experiments, the islands appeared to display a layered structure. The size of the islands did not scale with reaction time, which suggests growth rates for PZT crystals on the SrTiO 3 substrates and in solution (freestanding) were comparable.…”

“…The size of the islands did not scale with reaction time, which suggests growth rates for PZT crystals on the SrTiO 3 substrates and in solution (freestanding) were comparable. 17 The origin of the PZT microwires across the substrate is unclear, however certain attributes of the lines favour one explanation in particular. Firstly, their length, sometimes in excess of 1 mm, would appear to rule out crystallographic defects such as step edges, which persist over much shorter lengthscales in SrTiO 3 substrates, even after etching.…”

“…16 This was investigated in a recent paper that showed PZT stoichiometries close to the morphotropic phase boundary have a propensity to crystallise under hydrothermal conditions. 17 During the development of the hydrothermal technique there existed a variety of techniques for the synthesis of PZT with initial studies producing a mixture of lead titanate and lead zirconate. Choi et al showed that a simple 'one-stage' process could be used 18 which led to the development of processes for the hydrothermal synthesis of PZT films and increasingly as nanoparticles.…”

Low-temperature processing of solution-derived ferroelectric thin films

“…Furthermore, excess of Pb 2+ enhanced the crystallization of the perovskite phase. 73) Early experimental work on hydrothermal growth of polycrystalline PZT films on Ti-substrates also showed that alkaline medium was important for the formation of the PZT solid solution. The films were grown from the alkaline (KOH) solution from Pb-nitrate Zr-oxychloride and Ti-chloride in a two-step process on Ti-metal substrates, covered with a layer of a thermally-grown oxide.…”

Ultrasonic-assisted hydrothermal deposition of ferroelectric PbZrO3 thin film on NiTi-based superelastic shape memory alloys

“…In opposition to [27,31], our solution contains no titanium tetrachloride TiCl 4 because significant health hazards generally arise from the release of hydrogen chloride HCl. Rather, titanium dioxide TiO 2 , (also known as titanium(IV) oxide or titania), which is easier to handle, is preferred for preparation of a solution in combination with lead nitrate Pb(NO 3 ) 2 , zirconium oxychloride octahydrate ZrCl 2 O · 8 H 2 O, and potassium hydroxide KOH [10,16].…”