Magnetic fluctuations of goethite (a-FeOOH) analyzed through Al substituted samples

Author(s)

Valezi, D. F. ; Maeda, J. T. ; Vicentin, B. L. S. ; Mantovani, A. C. G. ; Spadotto, J. C. ; Urbano, A. ; Ivashita, F. F. ; Paesano, A. ; Magon, C. J. ; Di Mauro, E.

• Document type: Journal article
• Source: PHYSICA B-CONDENSED MATTER; v. 650, p. 8-pg., 2023-02-01.

Abstract

Goethite is a Fe3+ oxide-hydroxide very common in nature. At room temperature it shows an antiferromagnetic ordering, with Neel temperature of 400 K. Despite this, it is well known that it also presents magnetic fluctuations, whose origins are still under discussion in the literature. For this research, goethite samples were synthesized with and without Al substitutions. Micrographs obtained by transmission electron microscopy (TEM) showed the presence of defects, as kinks and steps, at the rod-shaped particles of samples with Al substitutions. With Electron Spin Resonance (ESR) and Mossbauer experiments, it was observed an increase in the magnetic fluctuations in these samples, due to imbalanced spins. Such effect was related to magnetic mismatch caused by the presence of Al ions at the goethite structure. This mismatch can be caused by the increase of crystalline defects, such as grain boundaries, or due to the proximity of Fe ions to diaspore-like clusters. (AU)

• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC