Gd2Zr2O7 ceramics synthesized by solid-state reactive sintering: Effects of starting powders with different-scale particle sizes

In this work, the effects of starting oxide powders with different-scale particle sizes on the synthesis of gadolinium zirconate pyrochlore (Gd2Zr2O7, GZO) and its physical properties were studied. Micron Gd2O3 (mu G), micron ZrO2 (mu Z), nano Gd2O3 (nG), and nano ZrO2 (nZ) powders were used. GZO ceramics were prepared by employing solid-state reactive sintering at 1300 degrees C, 1400 degrees C, 1500 degrees C and 1600 degrees C with mixed powders of different sizes (mu G mu Z, mu GnZ, nG mu Z and nGnZ). X-ray diffraction and Raman analyses of the ceramics revealed that nG has a more significant impact on the crystallization process than nZ. All ceramics synthesized with different sized oxide powders crystallized into pyrochlore phases except for those synthesized with mu GnZ mixed powders, which resulted in a fluorite phase. The results indicated that decreasing the particle size of only ZrO2 to synthesize pyrochlore-phase Gd2Zr2O7 with high crystallinity may not be effective. Samples obtained at 1500 degrees C were further analyzed. Scanning electron microscopy results revealed that all four ceramics have a non-homogeneous grain size and that the average grain size ranges from 5.40 to 8.30 mu m. In addition, the density and Vickers hardness measurements showed that the use of nanopowders significantly improves the mechanical properties.

Automated summary

This study investigated the effects of starting oxide powders with different particle sizes on the synthesis and physical properties of gadolinium zirconate pyrochlore (GZO). It was found that the use of nano powders had a more significant impact on the crystallization process and improved the mechanical properties of the ceramics.