Synthesis of nanosized Ce 0.75Zr 0.25O 2 porous powders via an autoignition: glycine nitrate process

Abstract

The GNP route has been successfully employed to generate nanosized, porous, stoichiometric, homogeneous Ce 0.75Zr 0.25O 2 powders. In this route, a precursor solution is prepared by mixing glycine with an aqueous solution of mixed (Ce–Zr) metal–nitrates in their stoichiometric ratios. Initially, the glycine mixed precursor solution was heated in a petri dish to evaporate the excess water to form a viscous semitransparent material. Then the petri dish was kept in a 5-l capacity beaker covered with a metallic mesh and then the temperature was increased slowly to 190–200 °C to autoignite the material. The combustion was self-sustaining and very rapid, producing yellowish coloured powders. The as-prepared powders were nanosized (20–35 nm), having a spherical shape, and were crystallized in cubic fluorite structure with lattice parameter a 0=5.38 Å. The powders showed a very wide pore size distribution in the range of 20–2500 Å as is shown by mercury porosimetry measurements with surface area ≈40.0 m 2/g. No change in crystalline phase was observed even after giving heat treatments to as-prepared powders up to 1000 °C for 4 h in air .The SEM/TEM studies on these powders confirmed their nanosized nature with porous structure.