Synthesis of yttria-doped strontium-zirconium oxide powders via ammonium glycolate combustion methods as precursors for dense ceramic membranes

Ammonium glycolate combustion was used to synthesize SrZr0.95Y0.05O3−x powders. Soluble metal-glycolate complexes, detected by infrared spectroscopy, were formed with Y+3 and Zr+4, which maintain atomic level mixing of metal cations with glycolic acid. Sr+2/glycolic acid mixtures did not form glycolate complexes. Temperature-programmed reaction studies showed that only precursor solutions with metal-glycolate complexes combust, indicating that the combustion is initiated by metal-glycolate complexes. Varying the ammonium hydroxide content and glycolic acid levels above that required to form glycolate complexes did not affect surface area and crystallinity. Decreasing the glycolic acid/nitrate ratio increases the temperatures reached during combustion. Thick disks prepared from co-precipitated and ammonium glycolate powders demonstrated that combustion synthesized powders reach higher densities. Surface area and SEM indicated that the ammonium glycolate powders have smaller particle sizes, which favor densification, than co-precipitated powders. C © 2001 Kluwer Academic Publishers