Magnetic susceptibility and triangular exchange coupling in the tourmaline mineral group

Journal of Physics and Chemistry of Solids
By: , and 

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Abstract

Magnetic susceptibilities of three iron-rich tourmaline crystals from Mexquitic (Mexico), Pierpont (New York), and Madagascar with different and known chemical compositions have been studied from 8° to 300°K. The iron atoms in the tourmaline crystal structure, space group R3m, a∼15·9, c∼7·2 , are situated at the three corners of an equilateral triangle and are close enough for magnetic exchange interaction. For buergerite, the Mexquitic sample, the susceptibility data lead to an exchange constant J/k of 7·5°K. Although the amount of aluminum would be sufficient to fill point position 18(c) exactly, the magnetic data are consistent with some substitution of ferric iron for aluminum, as previously determined from X-ray and neutron diffraction studies. Some aluminum thus replaces iron in position 9(b). Exchange constants were also estimated for the other two magnesium-iron specimens, of which the madagascar sample is aluminum deficient. The results agree with the evidence from optical spectra that there is considerable deviation from octahedral symmetry in the oxygen coordination polyhedra about the 9(b) and 18(c) point positions.

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Publication type Article
Publication Subtype Journal Article
Title Magnetic susceptibility and triangular exchange coupling in the tourmaline mineral group
Series title Journal of Physics and Chemistry of Solids
DOI 10.1016/S0022-3697(71)80039-2
Volume 32
Issue 7
Year Published 1971
Language English
Publisher Elsevier
Description 8 p.
First page 1441
Last page 1448
Country Madagascar, Mexico, United States
State New York
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