title: Low-symmetry spin hamiltonian and crystal field tensors analysis: Fe(3+) in natrolite.
abstract: Electron paramagnetic resonance study of a natural single crystal of natrolite was carried out at the frequency nu=36.772 GHz at room temperature. The angular dependence of the four symmetry-related spectra of Fe(3+) in the three crystallographic planes was fitted to a spin Hamiltonian (S=5/2) of symmetry C(i). The rank 4 crystal field tensors at tetrahedral sites were calculated using the point-charge model to determine the principal axes orientations of their cubic and trigonal components. The analysis of zero-field splitting tensors and comparison with crystal field ones suggests that Fe(3+) substitutes for Al(3+) with no significant distortion of the coordination tetrahedron in natrolite. Comparison of data for several natural and synthetic crystals reveals that the 4-rank zero-field splitting tensor invariants for Fe(3+) at the tetrahedral oxygen-coordinated sites are distinguishably smaller than those for Fe(3+) at octahedral sites. Such comparative analysis may help to determine the substitutional sites in other crystals.
authors.affiliation: Kazan State University, Kremlevskaya str. 18, Kazan, 420008, Russia.
authors.forename: V M
authors.initials: VM
authors.lastname: Vinokurov
authors.forename: J M
authors.initials: JM
authors.lastname: Gaite
authors.forename: G R
authors.initials: GR
authors.lastname: Bulka
authors.forename: N M
authors.initials: NM
authors.lastname: Khasanova
authors.forename: N M
authors.initials: NM
authors.lastname: Nizamutdinov
authors.forename: A A
authors.initials: AA
authors.lastname: Galeev
authors.forename: C
authors.initials: C
authors.lastname: Rudowicz