| An attempt was made to study the influence of origin and calcination treatments on
the development of crystallinity, surface area and the morphology of magnesia powders.
Magnesia powders were prepared by thermal decomposition/calcination of different
parent compounds namely, magnesium hydroxide, oxalate, carbonate, salicylate and
succinate. Calcination temperatures upto 900°C in either air or vacuum and soaking
time from half to 16 hrs were used. The development of crystallinity in the resultant
magnesia powders was studied at room temperatures by X-ray line broadening techniques.
The swface areas of the magnesia powders were determined by the BET method. A
limited study was made on the morphology of the powders using electron microscope.
It was found that at the decomposition temperature of the parent compound, the
crystallinity of the resultant magnesium oxide was very poor, and the surface area
extremely high. With an increase in calcination temperature, the crystallinity of the
oxide powders improved and the surface areas decreased. Prolonged soaking at any
calcination temperature, also resulted in a lower surface area; the lowering being more
significant at higher temperatures. The influence of the origin on the physical properties
namely-crystallinity, surface area and morphology were discernible even after calcination
at 700°C for periods upto 16 hrs. |
