INVESTIGATION OF THE CRYSTALLIZATION OF ZRO2 (Y2O3 3 MOL PERCENT) NANOPOWDER

The coprecipitation technique has been used to prepare ZrO2 (Y2O3 3 mo l%) nanopowder. The influence of residual NH4Cl and pH value on the cr ystallization of ZrO2 (Y2O3 3 mol%) nanopowder have been investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), x-ray diffraction (XRD), infrared spectrometry (IR), and trans mission electron microscopy (TEM) techniques. The IR spectra proved th at the presence of residual NH4Cl increased the amount of the hydroxo group. This led to serious gel agglomerate and free enthalpy decrease. Therefore, the crystallization of ZrO2 (Y2O3 3 mol%) nanopowder is gr eatly influenced by the residual NH4Cl. While there is no residual NH4 Cl, the crystallization takes place at 445 degrees C and is an exother mic process. On the contrary, with NH4Cl the crystallization takes pla ce at 376 degrees C and is an endothermic process. However, the pH val ue does not influence the crystallization of ZrO2 (Y2O3 3 mol%) nanopo wder.