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

Abstract

Metathetic solid-state reactions of alkaline earth perovskite zirconates (AZrO3, A = Ca, Sr, Ba) and lead sulfate (PbSO4) result in the relatively quick formation of perovskite PbZrO3 and the corresponding alkaline earth sulfate ASO4 at temperatures as low as 1023 K. The product can be described as a composite dispersion of small (<300 nm) particles of PbZrO3 on larger crystals of the alkaline earth sulfates. The solid-state reaction at 973 K between ZrO2, PbSO4, and K2CO3 followed by washing in water to remove K2SO4 provides a quick route to submicron (<1 μm) PbZrO3 powders starting from inexpensive precursors. In all the reactions, we believe the driving force to be the high enthalpy of formation of ASO4 or K2SO4. 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.

Synthesis and characterization of M3V2O8 (M = Ca, Sr and Ba) by a solid-state metathesis approach

“…NaCl) makes the reaction feasible (Panda et al 2003). Previous work by Kaner, Gopalakrishnan, and Parkin has established the versatility of the SSM method to synthesize various inorganic materials including metal pnictides, chalcogenides, carbides, silicides, and borides (Bonneau et al 1991;Treece et al 1994;Rao et al 1995;Gillan and Kaner 1996;Nartowski et al 1999;Gopalakrishnan et al 2000;Panda et al 2003;Mandal and Gopalakrishnan 2005). Metathesis reaction can be initiated by several external sources among which the reactions initiated by microwave radiation are very attractive, since it enables the product formation in a shorter duration of time without generating any residual wastes.…”

Mechanochemically assisted room temperature solid state metathesis reaction for the synthesis of MMoO4 (M = Ca, Sr and Ba)

“…Recently, Gopalakrishnan and his group synthesized several complex metal oxides through solid state metathesis route taking place at higher temperatures (Gopalakrishnan et al 2000;Gopalakrishnan 2004, 2005). In all these reactions metal halides have been used in conjunction with alkali and alkaline earth salts of main group anions; this has the advantage of making the reaction extremely exothermic and easy removal of the co-produced salt by water (Panda et al 2003). Recently, we communicated a preliminary report on the formation of calcium hydroxyapatite through a SSM route and realized that microwave medium can further accelerate to produce the products in short duration (Parhi et al 2004).…”

Template-free routes to porous inorganic materials

“…We call this reaction ''assisted metathesis'', in that the transfer of the sulfate species drives the reaction forward. 32 Similar reactions can be used to form mixtures of LaMnO 3 and K 2 SO 4 .…”