Agglomeration of nano-MgAl2O4 spinel from microemulsion and CVD techniques

MgAl2O4 nanoparticles have been prepared using a microemulsion synthesis te chnique (ME) and a chemical vapour deposition (CVD) approach. In the wet-ch emical route, the chain length of the surfactant molecules used to stabilis e the microemulsion as well as the annealing conditions (temperature and ti me) after preparation were varied. For CVD samples, the influence of the ta rget temperature and the consecutive annealing temperature were investigate d. A pinhole small-angle X-ray scattering camera was employed to determine the size and size distribution of primary particles as well as agglomerates . ME material is primarily obtained in the form of amorphous non-agglomerat ed particles; CVD raw material is crystalline and agglomerated. Upon anneal ing, agglomerates of ME material form and then grow faster than the primary particles do; in CVD material the agglomerates do not grow. Agglomeration is suppressed if the CVD process is carried out at elevated target temperat ure.