Characterization and microstructure investigation of novel ternary ZrO2–Al2O3–TiO2 composites synthesized by citrate–nitrate process

Abstract

The citrate–nitrate, sol–gel technique was used to prepare two different composites in the ZrO2–Al2O3–TiO2 system. The influence of two various compositions and calcination temperatures on the phase transformation and microstructure was investigated by the simultaneous thermal analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Results showed that while the combustion intensity was vigorous for the stoichiometric sample (ZAT-1) at 346 °C, the combustion occurs at a temperature range (270–500 °C) for the alumina-rich sample (ZAT-2). FTIR spectra confirmed the formation of complex compounds with citrate ligands. The XRD patterns revealed ZrTiO4 formation at 900 °C in both samples due to its thermodynamic stability; surprisingly, in stoichiometric samples calcined at 1100 °C, Al2TiO5 and monoclinic ZrO2 phases were detected, which indicated ZrTiO4 decomposition, whereas in alumina-rich samples, no ZrTiO4 decomposition was observed. The SEM micrographs also showed orthorhombic particles of ZrTiO4 with average particle size around 100 nm for the stoichiometric sample calcined at 1100 °C.