Patterns of aggregation in coprecipitation reactions

M.A. Pérez, A.B. Cabrera, R. Silva, M.E. Mendoza, J.L. Carrillo


Prismatic polycrystalline magnetic particles of iron oxalate were grown by
allowing the aggregation of the precipitating crystallites that were
produced by a reaction between aqueous iron salts and oxalic acid solutions.
The experiments were done at room temperature and under different pH conditions.
The particle-growing process was followed by optical microscopy and was then
digitally recorded. The effect of the presence of a static magnetic field on
the coprecipitation process was also analyzed. It was found that both pH
and applied field, considerably influence the aggregation of the
crystallites. This is clearly shown in the mean size and surface quality of
the particles. It was observed that high pH values produce larger particles
and that the applied field yields particles with a smoother surface than those
obtained without the application of the field. The polycrystalline particles
grow with the formation of clusters whose spatial distribution can be
characterized by scaling relations. From this scaling behavior, some
information about the spatial correlations occurring during
precipitation can be obtained.


Magnetic materials; aggregation in crystal growth

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Revista Mexicana de Física

ISSN: 2683-2224 (on line), 0035-001X (print)

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