Abstract
The plate-like goethite particles were synthesized from a ferrous hydroxide solution with oxyalkylamine (OAA) in the course of oxidation. The ratio of the crystallite sizes of (010) and (110) direction, D010/D110, were determined and its correlation with particle morphology was discussed. The value of D010.D110 was 1.3 times higher than the value calculated from a0 and b0 using Gibbs' equation. It shows growth of the (100) plane was restricted due to adsorption of OAA. Titration of ferrous sulfate with NaOH in the presence of acicular or plate-like goethite particles show that formation of plate-like goethite particles is attributed to the prevention of crystal growth along c-axis. Synthesis of plate-like goethite is related to the preferred adsorption site of alcoholic part of OAA, since plate-like goethite particles have never been synthesized from ammonium. Adsorption of OAA on (100) and (001) decreases the rate of crystal growth of (100) and (001), especially when free OAA concentration exceeds 0.4mol/dm3.
