Growth mechanisms of iron oxide particles of differing morphologies from the forced hydrolysis of ferric chloride solutions

Journal Article · Thu Apr 01 00:00:00 EST 1993 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1993.1150· OSTI ID:6784201

Bailey, J K; Brinker, C J ^[1]; MeCartney, M L ^[2]

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1. Sandia National Labs., Albuquerque, NM (United States)
2. Univ. of California, Irvine (United States)

To determine the growth mechanisms responsible for the different morphologies, the authors used time resolved transmission electron microscopy to follow the growth of iron oxide particles produced by the forced hydrolysis of ferric chloride solutions. The growth of three different hematite particle morphologies were investigated: cubes, spheres, and so-called double ellipsoids. The morphology of the particles depends on the concentration of FeCl[sub 3], the pH, and the temperature of aging. All solutions were seen to first produce rod-like particles of akaganeite ([beta]-FeOOH) which would then transform to hematite ([alpha]-Fe[sub 2]O[sub 3]), leading under different conditions to spheres, cubes, or double ellipsoids. For all solutions, the initially produced akaganeite rods form by homogeneous nucleation and subsequent growth. The hematite particles are produced by dissolution of the akaganeite rods and reprecipitation as hematite. For the double-ellipsoid-producing solution, the akaganeite rods remain unaggregated in solution. Hematite heterogeneously nucleates on these rods. In addition to growing outward, the hematite particle uses the rod as a template, and a collar forms, which grows along the rod, producing the double-ellipsoid shape. For a sphere-producing solution, the [beta]-FeOOH rods also remain unaggregated in solution but the akaganeite rods which are formed are shorter and dissolve before the growing hematite particles can use the rods as templates. For the cube-producing solution, the initially produced akaganeite rods aggregate into rafts. These rafts, formed from rods of similar length, have a cubic shape that they impart to the hematite which nucleates on the akaganeite raft. The findings indicate that the concentrations of starting compounds not only influence the kinetics of the reaction, but also influence the colloidal behavior.

• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6784201
• Journal Information: Journal of Colloid and Interface Science; (United States), Vol. 157:1; ISSN 0021-9797
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRON OXIDES
MORPHOLOGY
ABUNDANCE
AGGLOMERATION
COLLOIDS
CRYSTAL GROWTH
FLOCCULATION
HYDROLYSIS
IRON CHLORIDES
KINETICS
PH VALUE
PRECIPITATION
SHAPE
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
DECOMPOSITION
DISPERSIONS
ELECTRON MICROSCOPY
HALIDES
HALOGEN COMPOUNDS
IRON COMPOUNDS
LYSIS
MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
SEPARATION PROCESSES
SOLVOLYSIS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties