X-Ray and Mössbauer Study of Magnetic Black and from Mayotte Island

Braccini, Saverio; Krämer, Karl; Chapenoire, Stephane (2016). X-Ray and Mössbauer Study of Magnetic Black and from Mayotte Island. World journal of nuclear science and technology, 6(04), pp. 191-198. Scientific Research Publishing 10.4236/wjnst.2016.64020

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Natural magnetic black sands are known from several sites often located in areas of volcanic origin. Their elemental and mineral composition provides information on the geology of their territory and depends on several factors occurred during their formation. A sample of black sand was collected on the seashore of the island of Mayotte in the Indian Ocean and its magnetic part was investigated by means of energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), and Mössbauer spectroscopy at room temperature. The mineral composition is dominantly magnetite, in good agreement with samples collected in other sites of volcanic origin. Contrary to pure magnetite, a relevant fraction of Ti was detected by EDS. The 16% Ti and 1% Mn content increase the magnetite lattice parameter to 8.4312 (25) Å. The broadening of XRD lines pointed towards a significant degree of disorder. This was confirmed by Mössbauer spectroscopy and is attributed to the presence of Ti replacing Fe in the magnetite lattice. The presence of Ti modifies the local magnetic field on the Fe sites, leading to a broader and more complex Mössbauer transmission spectrum with respect to the one of pure magnetite. To study the effect of temperature, samples were heated for 12 hours to 600˚C and 800˚C in argon and to 1000˚C in air. Annealing in argon did not improve the crystallinity while annealing in air caused a complete decomposition of magnetite into hematite and pseudobrookite.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Applied Physics
08 Faculty of Science > Departement of Chemistry and Biochemistry
10 Strategic Research Centers > Albert Einstein Center for Fundamental Physics (AEC)

UniBE Contributor:

Braccini, Saverio and Krämer, Karl

Subjects:

500 Science > 530 Physics
500 Science > 540 Chemistry

ISSN:

2161-6795

Publisher:

Scientific Research Publishing

Language:

English

Submitter:

Karl Krämer

Date Deposited:

10 Jan 2017 11:36

Last Modified:

15 Jan 2017 02:13

Publisher DOI:

10.4236/wjnst.2016.64020

BORIS DOI:

10.7892/boris.90909

URI:

https://boris.unibe.ch/id/eprint/90909

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