Preparation of nanosized hematite particles by mechanical activation of goethite samples

Nanosized single crystals of hematite with a very narrow particle size dist ribution were prepared by mechanical activation of two different goethite s amples. Both goethite samples transformed completely into hematite after 70 h grinding time. Transmission electron microscopy showed that the final pa rticles were spherical in shape and of similar to 17 nm average particle si ze. This particle size was coincident with that estimated from specific sur face measurements, indicating that the hematite samples consisted of nonpor ous and nonaggregated particles. The crystallite size, calculated from the broadening of the XRD peaks, in the hematite samples indicated that particl es consisted of single crystals, No influence of the precursor was observed in the products, so both goethite samples yielded identical rounded single crystals with a narrow particle size distribution.