On the preparation of nanosized Al2(WO4)3 by a precipitation method

Nanosized aluminum tungstate, Al2(WO4)3, is prepared by a precipitation reaction between Na2WO4 and Al(NO3)3. The structure of the precipitated composition is determined by powder XRD analysis, IR and 27Al MAS NMR spectroscopy. The thermal properties are examined by DSC, DTA and TG analyses combined with gas evolved analysis. Particle sizes and morphology are examined by TEM analysis. Precipitation reaction leads to the formation of an amorphous composition, which consists of dimer and trimer aluminum hydroxide species and WO42− groups. Finely dispersed particles with dimensions of about 25 nm are formed. The precipitated composition is decomposed to amorphous Al2(WO4)3 immediately after H2O release. At 630 °C, amorphous Al2(WO4)3 crystallizes in an orthorhombic modification of Al2(WO4)3, the enthalpy of crystallization being 58 kJ/mol. The nanosized particles remain intact after the crystallization of amorphous Al2(WO4)3. A significant particle growth take places when nanosized Al2(WO4)3 is heated from 600 to 800 °C.

Nanosized aluminum tungstate, Al2(WO4)3, is prepared by a precipitation reaction between Na2WO4 and Al(NO3)3.Figure optionsDownload as PowerPoint slide