Temperature Influence on the Properties of Freely Poured Nano-Sized Inorganic Oxide Powders

A comparative investigation was performed on the possibility of controlling the average sizes of nano-sized powders of silicon dioxide and aluminum oxide, obtained by electron-beam evaporation and by pyrogenic, liquid chemical, and plasma chemical methods, by keeping them in the temperature range 800 – 1300°C in an air atmosphere. The average sizes of the resulting particles were estimated from measurements of the specific surface area using the Brunauer–Emmett–Taylor (BET) adsorption method at liquid nitrogen temperature. The crystallographic parameters in the treated powders were assessed by means of x-ray diffraction analysis. It is shown that by making a suitable choice of temperatures and initial powder it is possible to achieve in the resulting powder the phase composition and an average particle size close to a specified value.