Papers by Keyword: β-Fe₂O₃

Abstract: Maghemite and hematite nanospheres were synthesized by using the Sol-gel technique. The structural properties of these nanosphere powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM),and pore size distribution.Hematite phase shows crystalline structures.The mean particle size that resulted from BET and XRD analyses were 4.9 nm and 2 nm. The field emission scanning electron microscopy shows iron-oxide powder is composed of nanosized particles, but in nanosized aggregates (agglomeration of particles). It can be seen from transmission electron microscopy that the size of the particles are very small which is in good agreement with the FESEM and the Xray diffraction. TEM and FESEM confirmed that the iron-oxide powder is composed of sizes from 8 nm to 10 nm. The BET and pore size method were employed for specific surface area determination.

Abstract: The influence of reaction temperature on phase evolution of iron oxide hollow nanoparticles during chemical vapor condensation (CVC) process using iron acetylacetonate was investigated. X-ray diffraction (XRD) analyses revealed that three iron oxide phases (α-Fe2O3, γ-Fe2O3, and Fe3O4) and a mixture of β-Fe2O3 and small amount of γ-Fe2O3 were synthesized at 700oC and 900oC, respectively. TEM observation disclosed that the iron oxide particles are almost composed of hollow structured nanoparticles of 10~20 nm in size and 3~5 nm in shell thickness. This result implies that reaction temperature determining various reaction parameters plays an important role for the phase- and structural evolutions of iron oxide hollow nanoparticles. Especially, the present investigation attempted to explain temperature dependence of the phase evolution of β-Fe2O3 hollow nanoparticles in association with the decomposition of iron acetylacetonate.