Preparation of PbZrO3/ASO4 Composites (A = Ca, Sr, Ba) and PbZrO3 by Metathetic Reactions in the Solid State: Metathetic Exchange of Divalent Species

Metathetic solid-state reactions of alkaline earth perovskite zirconates (AZrO 3, A = Ca, Sr, Ba) and lead sulfate (PbSO 4 ) result in the relatively quick formation of perovskite PbZrO 3 and the corresponding alkaline earth sulfate ASO 4 at temperatures as low as 1023 K. The product can be described as a composite dispersion of small (<300 nm) particles of PbZrO 3 on larger crystals of the alkaline earth sulfates. The solid-state reaction at 973 K between ZrO 2, PbSO 4, and K 2 CO 3 followed by washing in water to remove K 2 SO 4 provides a quick route to submicron (<1 μm) PbZrO 3 powders starting from inexpensive precursors. In all the reactions, we believe the driving force to be the high enthalpy of formation of ASO 4 or K 2 SO 4 . The reactions presented here provide proof of concept for the preparation of a number of important polar lead-based perovskite phases under relatively mild conditions: (i) as composites, (ii) as small particles, and (iii) possibly as porous monoliths.