Sintering studies of nano-crystalline zinc oxide

Sintering and grain growth of nano-crystal line uncloped ZnO has been studied in detail over a wide range of temperature and holding time. Below 800 degrees C, sintering of over 70% theoretical density is not observed, irrespective of particle size. At 900 degrees C for 6 h, the nano-crystalline sample sinters to 99% of theoretical density whereas the density for as received sample is 93% of theoretical density. However, at 1300 degrees C or higher, the densification is found to be much faster and after a few hours becomes independent of holding time. Grain growth studies reveal a similar feature of attaining saturation over holding time. The average saturated grain size is found to be similar to 1.5 and similar to 2.2 mu m at 800 and 900 degrees C, respectively, while at 1300 degrees C or higher, it is in between 12 and 13 mu m. (C) 2006 Elsevier Ltd and Techna Group S.r.l. All rights reserved.