Mössbauer Effect Determination of Particle Size in Microcrystalline Iron-Manganese Nodules

TLDR: In this article, the 57Fe Mossbauer effect of two iron-manganese nodules in which the iron oxide phase could not be detected by X-ray or electron diffraction was investigated.

Abstract: IRON-MANGANESE nodules from the ocean floor have been extensively studied1–6 But, because of the fine grain size of the particles of the nodules, structural identification by X-ray and electron diffraction techniques is difficult and the mineralogy of the iron oxide phase has not been well characterized The observation of the Mossbauer spectrum—in which each nucleus absorbs γ-rays independently—is not limited by particle size in the same way as is the observation of Bragg peaks in diffraction measurements, in which radiation must be scattered coherently from a large number of atoms The magnetic hyperfine splitting in the Mossbauer spectrum of magnetic materials is affected, however, when the particles are so small that they become superparamagnetic7–10 We describe here an investigation using the 57Fe Mossbauer effect of two iron–manganese nodules in which the iron oxide phase could not be detected by X-ray or electron diffraction