Growth model for nanomallets of zinc oxide from a catalyst-free combust-oxidised process

A growth model is proposed for a newly found nanostructure of zinc oxide, namely nanomallet, that is prepared via a catalyst-free combust-oxidised (CFCO) process (better known as the French process). In the CFCO process, molten zinc is vaporised and instantaneously oxidised in normal atmosphere to produce high purity zinc oxide. With the help of high-resolution field emission scanning electron microscope (FESEM) set at 15 kV incident electron energy, clear images of mallet-like nanostructure are observed. These polycrystalline structures can be classified into polyhedral and rectangular nanomallets. The polyhedral nanomallet has higher O/Zn relative atomic mol% ratio based on EDAX data and its handle tend to grow along [0 0 0 2] direction. The quasi-rectangular nanomallet tend to grow along [101¯0] direction for both the head and handle. Local temperature and oxygen partial pressure play a key role in determining the preferred nanostructures that include rectangular-like, polyhedral-like and taper-faceted structures.