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Pyrochlore structured Gd2Zr2O7 and Nd2Zr2O7 are produced via complex precipitation processing. A suite of characterization techniques, including FTIR, Raman, X-ray and electron diffraction, TEM, SEM as well as nitrogen sorption are employed to investigate the structural and grain size evolution of the synthesized and calcined powder. Results show that Gd2Zr2O7 with the pyrochlore structure are produced after calcination at 1400°C for 12h while Nd2Zr2O7 has already formed the pyrochlore structure at 1200°C. This method allows the formation of dense materials at relatively low temperature, with bulk densities over 92% of the theoretical values achieved after sintering at 1400°C for 50h. This unique aqueous synthetic method provides a simple pathway to produce pyrochlore lanthanide zirconate without using either organic solvent and/or mechanical milling procedures, making the synthesis protocol an attractive potential scale-up production of highly refractory ceramics. [ABSTRACT FROM AUTHOR]

Lanthanum zirconate has been prepared via a new chemical synthesis method by combining sol-gel processing and complex precipitation. The synthesis was carried out in aqueous solution under ambient conditions. The synthesized powder possessed the pyrochlore superstructure upon calcination above 1200°C. A suite of characterization techniques, including FTIR, Raman, X-ray and electron diffraction, TEM, SEM, and nitrogen sorption were employed to investigate the microstructural evolution and bulk properties. Dense ceramics (>90% relative density) were obtained after sintering at 1400°C, without need for additional processing (i.e., hot or cold isostatic pressing) or any milling steps. A mechanism has been proposed that elucidates molecular assembly of this chemical synthesis method. [ABSTRACT FROM AUTHOR]