Synthesis and characterization of sol–gel derived ZrO2 doped Al2O3 nanopowder

Al2O3–ZrO2 composite gel precursor powder containing 5–15 mol% ZrO2 was prepared by wet chemical route. The washed gel containing pseudoboehmite and amorphous zirconia was characterized with respect to DTA/TG, XRD and IR spectroscopy. The DTA/TG result indicates three-stage decomposition for pseudoboehmite and single stage decomposition for amorphous zirconia. In the calcined powder phase evolution of Al2O3 follows the sequence pseudoboehmite → bayerite → boehmite → γ-Al2O3 → θ-Al2O3 → α-Al2O3, while that of ZrO2 follows amorphous ZrO2 → t-ZrO2 → (t + m)ZrO2. FTIR studies revealed that the number of M–OH and M–O bond increase on increasing mol% of ZrO2 due to a change in the cationic charge of the composite powder. TEM photograph of calcined powder showed both dispersed nano-size spherical particle as well as agglomerated particles. EPMA confirmed the near uniform distribution of zirconia particles in the alumina matrix.