Synthesis and characterization of ZnAl2O4 spinel from Zn(II) and Al(III) carboxylates

Abstract

In this paper, zinc aluminate (ZnAl2O4) nanoparticles were obtained by a new synthesis method, thermal decomposition of Zn(II) and Al(III) carboxylates mixture. Complex combinations were obtained in the redox reaction between Zn(NO3)2·6H2O, Al(NO3)3·9H2O, and 1,3-propanediol at ~130 °C. The mechanism of Zn(II) and Al(III) carboxylates formation and decomposition was observed by thermal analysis and Fourier transform infrared spectroscopy. Zn(II) carboxylate, Al(III) carboxylate, and Zn(II) and Al(III) carboxylates mixture were annealed at different temperatures. Metal oxides synthesized from carboxylates precursors in single metal systems crystallized very well at 400 °C (ZnO) and weak at 800 °C (Al2O3), as shown by X-ray powder diffractometry. Homogenous mixture of Zn(II) and Al(III) carboxylates heated at 400 °C has led to a mixture of amorphous ZnO and Al2O3, which reacted forming at 600 °C well-crystallized ZnAl2O4, with mean crystallites size of 14.2 nm. The decomposition of carboxylates precursors is an appropriate method to obtain ZnAl2O4 spinel as well-crystallized single phase at low temperatures.