X-ray diffractometric study of dehydration products of goethite and lepidocrocite
Abstract
Two polymorphic modifications of iron oxide hydrate are known in nature – goethite α‑FeO(OH) or HFeO₂ and lepidocrocite γ‑FeO(OH). However, until now in the literature and practice, the name hydrogoethite is common for loose ferruginous formations, which, according to E. Ya. Rode and B. K. Brunovsky, represents a solid solution of zeolite‑type water in goethite. The presence of such water should cause an increase in the interplanar distances and, consequently, in the unit cell parameters of the so‑called hydrogoethite (the same applies to hydrohematite). But, as X‑ray diffractometric studies show, the changes in the values of interplanar distances are so insignificant that they are within experimental error. Such loose formations, apparently, are finely dispersed goethite containing a considerable amount of adsorbed water. Debye patterns of hydrogoethite differ from ordinary goethite only by strong blurriness and width of the diffraction lines.
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