Large surface area ZnAl2O4 powders prepared by a modified combustion technique

• Large surface area ZnAl2O4 powder was prepared using a new combustion technique.
• Basically, this new technique relies on using zinc acetate instead of zinc nitrate.
• The nanocrystalline (6 nm) ZnAl2O4 powder had a specific surface area of 127 m2/g.
• The addition of NH4NO3 increased even more the specific surface area to 201 m2/g.
• At the same time, the average crystallite size of ZnAl2O4 decreased to 2 nm.

ZnAl2O4 powders with large surface area have been prepared using an original combustion technique which relies on using zinc acetate instead of zinc nitrate. Properties of the resulted ZnAl2O4 powders were discussed in relation to the synthesis conditions, standard enthalpy of reaction and the total amount of gases released in each case. ZnAl2O4 powder resulted from the classical combustion synthesis (metal nitrates and urea) had larger crystallite size (23 nm) and small BET surface area (20 m2/g), due to the large amount of heat (−10099 kJ/mol) released during the combustion reaction. The replacement of zinc nitrate by zinc acetate decreased the amount of heat released during the combustion reaction (−7743 kJ/mol), so that the resulted ZnAl2O4 powder had larger BET surface area (127 m2/g) and smaller crystallite size (6 nm). The addition of NH4NO3 increased furthermore the BET surface area of ZnAl2O4 powder (201 m2/g) as the volume of gases released during combustion increased. At the same time the ZnAl2O4 crystallite size decreased to 2 nm.