Two iron(III) oxide hydroxides, namely alpha-FeOOH (goethite) and gamm
a-FeOOH (lepidocrocite), were studied by means of Differential Thermal
Analysis (DTA), Thermogravimetry (TG) and Emanation Thermal Analysis
(ETA) on heating in air. Surface area, Transmission Electron Microscop
y (TEM) and X-ray diffraction patterns (XRD) were used for the charact
erization of the intermediate products of the thermal treatment. ETA e
nabled us to obtain a new sensitive insight into the aggregation proce
sses of solid particles.