Magnetic behavior of trioctahedral micas with different octahedral Fe ordering

This contribution is finalized at the discussion of the magnetic structure of two samples, belonging to phlogopite–annite [sample TK, chemical composition IV (Si 2.76 Al 1.24 ) VI (Al 0.64 Mg 0.72 Mn 0.03 Ti 0.15 ) (K 0.96 Na 0.05 ) O 10.67 (OH) 1.31 Cl 0.02 ] and polylithionite–siderophyllite joint...

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Bibliographic Details
Published inPhysics and chemistry of minerals Vol. 39; no. 8; pp. 665 - 674
Main Authors Pini, Stefano, Brigatti, Maria Franca, Affronte, Marco, Malferrari, Daniele, Marcelli, Augusto
Format Journal Article
LanguageEnglish
Published Berlin/Heidelberg Springer-Verlag 01.09.2012
Springer Nature B.V
Subjects
Cations
Chemical composition
Crystallography and Scattering Methods
Earth and Environmental Science
Earth Sciences
Geochemistry
Magnetic fields
Magnetic permeability
Magnetic properties
Magnetic structure
Mineral Resources
Mineralogy
Organic chemistry
Original Paper
Spin glasses
Temperature dependence
XAS
Polylithionite
Siderophyllite
Crystal chemistry
Magnetic properties
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Summary:This contribution is finalized at the discussion of the magnetic structure of two samples, belonging to phlogopite–annite [sample TK, chemical composition IV (Si 2.76 Al 1.24 ) VI (Al 0.64 Mg 0.72 Mn 0.03 Ti 0.15 ) (K 0.96 Na 0.05 ) O 10.67 (OH) 1.31 Cl 0.02 ] and polylithionite–siderophyllite joints [sample PPB, chemical composition IV (Si 3.14 Al 0.86 ) VI (Al 0.75 Mg 0.01 Mn 0.01 Ti 0.01 Li 1.09 ) (K 0.99 Na 0.01 ) O 10.00 (OH) 0.65 F 1.35 ]. Samples differ for Fe ordering in octahedral sites, Fe 2+ /(Fe 2+  + Fe 3+ ) ratio, octahedral composition, defining a different environment around Fe cations, and layer symmetry. Spin-glass behavior was detected for both samples, as evidenced by the dependency of the temperature giving the peak in the susceptibility curve from the frequency of the applied alternating current magnetic field. The crystal chemical features are associated to the different temperature at which the maximum in magnetic susceptibility is observed: 6 K in TK, where Fe is disordered in all octahedral sites, and 8 K in PPB sample, showing a smaller and more regular coordination polyhedron for Fe, which is ordered in the trans -site and in one of the two cis -sites.
ISSN:0342-1791
1432-2021
DOI:10.1007/s00269-012-0520-1