Synthesis And Coloration Control Of Alpha-Feooh Rods Using Closed System

This paper details the synthesis of alpha-FeOOH (goethite) rods through the reaction of iron (III) nitrate with KOH as a strong base, and shape control of the particles for use as a yellow inorganic pigment. The crystal phase of the alpha-FeOOH crystal with OH content according to the addition of KOH and the change in morphology were investigated. The optical properties varied with the aspect ratios, and the yellowness increased with increasing aspect ratio. However, the enhanced chromaticity characteristics reversed beyond a certain critical aspect ratio. Thus, the relative optimal aspect ratio of the alpha-FeOOH rods as a vivid yellow inorganic pigment was derived. The morphology and coloration of the prepared rods were investigated in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy, and CIE Lab color parameter measurements.