Electron paramagnetic resonance of Fe3+ in diopside and spodumene

Abstract

A study of the EPR spectrum of Fe3+ in diopside CaMg(SiO3)2 and spodumene LiAl(SiO3)2 has been made. It permits the calculation of all the constants of the spin Hamiltonian. We show that the pseudosymmetry axes of the fourth order tensor of the spin Hamiltonian are the same as the axes of the immediate environment of the Fe3+. From the fourth order constants of the spin Hamiltonian it is possible to obtain qualitative information about the Fe3+ environment. In both crystals, the Fe3+ is in the M 1 site. We show that the M 1 site is smaller and more distorted in spodumene than in diopside, and that in spodumene there is large tetragonal distortion along the M 1–01′ direction. It is seen that the information we obtain agrees very well with the crystallographic results.

EPR Study of Fe3+- and Ni2+-Doped Macroporous CaSiO3 Ceramics

“…-containing materials, a symmetric and isotropic line at g À 4.04.2 is observed. Castner et al [36] explained it as arising from the middle Kramers doublet containing an admixture of different )m j ñ states, which are caused by the presence of a rhombic term E(S x 2 # S y 2 ) in the Hamiltonian. According to the diagram of Gaite and Michoulier [36], l should be close to zero to observe g " 6.0, i.e., the crystal field Hamiltonian and thus the ZFS one for this Fe 3!…”

“…An increase in l represents a deviation from axial symmetry toward orthorhombic symmetry. Gaite and Michoulier [36] computed a relationship between g and l that allows to obtain information on the deviation from the axial symmetry of the site from the observed resonance fields. When Fe 3!…”

Parameterization Schemes in Solid State Physics

“…A related, but more systematic technique has been employed by Michoulier and Gaite (1972) and Gaite and Michoulier (1973) in the study of S-state ion spin-Hamiltonians. Their approach is to minimize expressions defined in terms of sums of squares of parameters which would be exactly zero in a given symmetry with respect to the angular orientation of the coordinate system.…”

“…It is interesting that most work on the crystal field for ions with a partly filled 3d shell has been carried out by chemists, who prefer to work with orbital matrix elements, and refer to the model as the angular overlap model (see e.g. Schaffer and J0rgensen 1965;Gerloch and Slade 1973). On the other hand, the richer data available for the lanthanides have attracted physicists, who prefer to use phenomenological crystal field parameters and the associated superposition model .…”

TL, ESR and reflectance in natural diopside crystal

“…The M1 site is smaller than the M2 site and lies between the apices of opposing tetrahedra forming an almost regular octahedron. The M2 site lies between the bases of the tetrahedra forming distorted 6-or 8-fold sites.Many studies on structure [3,4] [12] showed that Fe 3+ occupies the M1 site due to the less distortion of this site. Gaite [13], taking into account all the previous ESR calculations got to the conclusion that Mn 2+ in diopside, can be located in both M1 and M2 positions.…”