Influence of milling, sonication and fluoride doping of pseudoboehmites on their phase transformation behaviour to corundum

The influence of fluoride doping, sonication and milling on the phase transformation of pseudoboehmites to corundum was explored. Followed by XRD and MAS NMR, it can be shown that the crystal structure of the dopant as well as the particle size of the samples is of extreme importance on their thermal behaviour. The combination of ultrasound treatment or rather high energy ball milling and fluoride doping leads to an early beginning of corundum formation at temperatures as low as 700 °C.