Magnesium oxide nano powders with different particle sizes (10~100 nm) and crystallinity were synthesized by the citric acid sol-gel method using magnesium nitrate hexahydrate as the precursor. The effect of citric acid on the stability of the sol-gel and the effect of roasting temperature on the particle size and crystallinity of the powders were investigated.
The results showed that the stability of the gels was poor when citric acid was not introduced, and the magnesium oxide products had larger particle size and more serious agglomeration. After the introduction of citric acid, and when water: magnesium nitrate hexahydrate: citric acid: ethanol=100:9:9:2.1(molar ratio), a stable gel system could be formed. The roasting temperature has no effect on the chemical composition and crystal morphology of the magnesium oxide powder, but has a significant effect on the crystallinity and particle size of the powder. The particle size is 50~100nm, the crystallinity is higher and the crystalline phase is more complete.