Abstract
Positron annihilation lifetime spectroscopy (PALS) has been used to study the vacancy-type defects in fine-particle goethites (α-FeOOH). The PALS spectra reveal three components. The intermediate lifetime component (τ2, I2) is attributed to positrons trapped at vacancy defects. The relative intensity of the intermediate lifetime component, I2, increases significantly with decreasing Néel temperature, and this increase is attributed to increasing concentration of vacancy defects. These results support a model of magnetic ordering of clusters arising from a high concentration of iron vacancies which reduces the Néel temperature in these fine-particle goethites.
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Bocquet, S., Hill, A.J. Correlation of Néel temperature and vacancy defects in fine-particle goethites. Phys Chem Minerals 22, 524–528 (1995). https://doi.org/10.1007/BF00209379
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DOI: https://doi.org/10.1007/BF00209379