Insofar as the additional step woul

Insofar as the additional step would occur first, it means that the density is still low like green density of around 50% and the particles are partly surrounded by gas. The observations of Lange12,13 related to particles surrounded by gas and presenting large shape factors are applicable to this case: he pointed out that this type of grooved needles when heated allow the system to relax to its lowest energy level. We have observed this phenomenon during calcination for needles7 and Fig. 1a. Given that the diameter of the needles is less than the thickness of the platelets, higher energy is required to spheroidize, and that means,according to Langue’s interpretation, higher energy for crystallites to reach the thickness of the platelets.