Structural investigations on inorganic Al2O3-ZnO composites

The present work deals with the preparation and characterization of Al2O3/ZnO composites under the effect of structural and temperature changes. A sol-gel method of preparing Al2O3/ZnO composites with different concentrations of ZnO and Al2O3 was used. Materials with the extremely high Al2O3 concentration (80 mol%) have been simply prepared by the sol-gel technique. Al-27 NMR spectroscopy, X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) examined the structural features of all the samples. Al-27 NMR showed a significant improvement in the product composition with the change of the Al2O3 to ZnO molar ratios. The main units that existed in the Al2O3 rich sample (80 mol%) are the structured groups AlO6, AlO5 and AlO4. The main unit in the lower Al2O3 concentration (20 mol%) is only AlO4 coordination. Through adding Al2O3, the crystalline configuration in the pure ZnO matrix is fully transformed into one of the amorphous forms. The amorphous composition of Al2O3/ZnO is retransformed into crystalline forms after calcination. The presence of different Al2O3 coordination such as AlO6, AlO5 and AlO4 is considered as the main cause for mismatching between different structural units that leads to transformation of crystalline into non-crystalline structure.

Automated summary

This study focuses on the preparation and characterization of Al2O3/ZnO composites with different concentrations using a sol-gel method. Analysis of the structural features reveals the significant impact of varying Al2O3 to ZnO ratios on the product composition.