Combustion synthesis and properties of nanostructured ceria-zirconia solid solutions

Nanostructured ceria-zirconia solid solutions (Ce1-xZrxO2, x = 0 to 0.9) have been synthesized by a single step solution combustion process using cerous nitrate, zirconyl nitrate and oxalyl dihydrazide (ODH) / carbohydrazide (CH). The as-synthesized powders show extensive XRD line broadening and the crystallite sizes calculated from the XRD line broadening are in the nanometer range (6-11 nm). The combustion derived ceria zirconia solid solutions have high surface area in the range of 36-120 m(2)/g. Calcination of Ce1-xZrxO2 at 1350 degrees C showed three distinct solid solution regions: single phase cubic (x less than or equal to 0.2), biphasic cubic-tetragonal (0.2 < x less than or equal to 0.8) and tetragonal (x > 0.8). When x 0.9, the metastable tetragonal phase formed transforms to monoclinic phase on cooling after calcination above 1100 degrees C. The homogeneity of Ce1-xZrxO2 has been confirmed by EDAX analysis. The Temperature Programmed Reduction (TPR) measurement of Ce0.5Zr0.5O2 was carried out with Hz and the TPR profile showed two water formation peaks corresponding to the utilization of surface and bulk oxygen. (C) 1998 Acta Metallurgica Inc.