Preparation and characterization of lanthanum zirconate

Lanthanum zirconate has been prepared by citrate synthesis, by coprecipitation and by solid state decomposition of metal nitrate urea mixtures. The relative advantages of these methods with respect to surface area and reproducibility are investigated. The lanthanum zirconate phase is formed by the urea decomposition method without any additional heat treatment. In the case of the citrate and coprecipitation methods the pyrochlore phase is formed only after heating the precursor above 900°C. The citrate method yields the highest surface area, the coprecipitation method gives more reproducible results. However, after washing with ethanol the coprecipitated sample has much higher surface area compared with the citrate method.